Part II

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4 Urweltmuseum GEOSKOP / Burg Lichtenberg (Pfalz), Burgstraße 19, 66871 Thallichtenberg,. Germany. 1. Introduction: Geology, stratigraphy and ...
Part II The Carboniferous – Permian basins in Saxony, Thuringia, and Saxony-Anhalt of East Germany Jörg W. Schneider1, Ronny Rößler2, Ralf Werneburg3, Frank Scholze1 & Sebastian Voigt4 1

TU Bergakademie Freiberg, Geological Institute, Bernhard-von-Cotta-Str. 2, 09599 Freiberg, Germany; [email protected] 2 DAStietz, Museum für Naturkunde, Moritzstraße 20, 09111 Chemnitz, Germany 3 Naturhistorisches Museum Schloss Bertholdsburg, Burgstr. 6, 98553 Schleusingen, Germany 4 Urweltmuseum GEOSKOP / Burg Lichtenberg (Pfalz), Burgstraße 19, 66871 Thallichtenberg, Germany

1. Introduction: Geology, stratigraphy and palaeontology of the excursion area The syn- to post-orogenic evolution of Variscan Central Europe was dominated by the formation of a variety of basins (Fig. 43–45), into which the erosional debris of the orogen, the so called molasses, was deposited. The sedimentary and volcanic fill of these basins records apart from the erosion of the Variscan orogen the tectonic and magmatic activity associated with the post-Variscan reorganization of the stress field that led to Permian rifting and also the Carboniferous and Permian climatic development with wet and dry phases which are superimposed on the general aridisation during this time. The character of the basins of the Saxo-Thuringian Zone and bordering areas (Fig. 43) changes systematically from north to the south. Located to the north of the orogenic deformation front, the Variscan foredeep basin was mainly filled by submarine turbidite sequences and only in his final stage by paralic to increasingly continental clastics (e.g., in the Ruhr, the Emsland, and the NorthMecklenburg-Rügen area of Germany). Peri-montane basins (e.g., Hainichen basin, Saale and Saar basin) are situated at the transition from the foredeep basin to the mountain slopes in the south. These basins may have had the character of wide depressions opening into the foreland, where sediments transported by rivers formed alluvial plain and delta complexes in the area of the increasingly filled up foredeep. Large valley-like basins between the mountain chains of the orogen are called intermontane basins (e.g., the Bohemian basins). Additionally, there are smaller basins within the mountains ranges, the intramontane basins (e.g., Zwickau basin). The latter two basin types belong to the Variscan internides. In contrast to the foredeep and the perimontane basins, the early history of these basins is not well known. They were uplifted and eroded together with the orogen. Only after the last phase of strong uplift during the Namurian, the geological record for the development of these basins became more complete. Fig. 43. Outcrop areas of Carboniferous and Permian continental basins in Central Europe. 1 paralic Namurian to Westphalian Aachen and Campine basins of the Variscan foredeep. 2 paralic Namurian to Westphalian Ruhr basin of the Variscan foredeep. 3 Westphalian to Permian Saar-Nahe Basin. 4 Stephanian-Permian Saint-Die and Ville basins of the Vosges area. 5 Stephanian-Permian Baden-Baden Basin. 6 Permian Wetterau Basin. 7 Stephanian/Permian Thuringian Forest Basin. 8 Permian IIfeld Basin. 9 subsurface Stephanian relict basin of the Variscan foredeep in the area of the later Southern Permian Basin. 10 StephanianPermian Saale Basin. 11 Permian NW Saxon Basin and Volcanite Complex. 12 Westphalian to Permian Erzgebirge Basin. 13 Stephanian/Permian Döhlen Basin. 14 Westphalian Schönfeld-Altenberg Basin. 15 Westphalian Central and West Bohemian basins. 16 Cesky Brod area of the Stephanian to Permian Blanice graben. 17 Westphalian to Permian Krkonose Basin. 18 North Sudetic Basin. (From Schneider & Romer, 2010; based on Schäfer, 2005).

Repeated tectonic activity led to relief rejuvenations, basin reorganisation, and formation of new basins, as well as reorganisations of the drainage systems with erosional hiatuses in the Variscan

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internides (e.g., Saar-Nahe basin) and the formation of new basins (e.g., Saale basin) at the Westphalian/Stephanian transition. The Franconian movements at the Stephanian/Rotliegend (Autunian) transition are characterised by increased magmatic activity, which produced huge volcanic complexes, as for instance the Gehren Subgroup with close to 1,000 m of volcanites in the Thuringian Forest basin, the first stage of the Halle Volcanic Complex in the Saale basin, and the lower part of the North German Volcanic Complex in the North German-Polish basin (Southern Permian basin). Associated tectonic activity resulted in relief rejuvenations and progradation of conglomerate fans. New Rotliegend basins are formed north of the Variscan orogen in the area of the later North German-

Fig. 44. Typical Carboniferous and Permian fossils of the Saxo-Thuringian basins. a Seed fern Alethopteris subdavreuxi, Westphalian D, Oberhohndorf, Zwickau Basin, scale bar 2 cm (collection TU Bergakademie Freiberg). b Cockroach zone species Sysciophlebia ilfeldensis, L. Rotliegend Netzkater Formation, IIfeld Basin, scale bar 0.5 cm (collection F. Trostheide). c Palaeoniscid fish Elonichthys, L. Rotliegend Goldlauter Formation, Gottlob quarry, Thuringian Forest Basin, scale bar 1 cm (collection TU Bergakademie Freiberg). d Male cone of the conifer Walchia piniformis, L. Rotliegend Goldlauter Formation, Cabarz quarry, Thuringian Forest Basin, scale bar 1 cm (collection TU Bergakademie Freiberg). e Branchiosaur zone species amphibian Melanerpeton tenerum, Lower Rotliegend Börtewitz lake horizon, Oschatz Formation, NW Saxony Basin, scale bar 1 cm (collection Geological Survey of Saxony). f Ichniotherium sphaerodactylum, the track of a diadectid reptile, U. Rotliegend Tambach Formation, Bromacker quarry, Thuringian Forest Basin, scale bar 10 cm (Holotype, collection Natural Museum Gotha). g Group of the synapsid reptile Pantelosaurus saxonicus, Lower Rotliegend Niederhäslich Formation, Döhlen Basin, former Königin Carola coal mine, scale bar 20 cm (collection Geological Survey of Saxony).

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Polish basin, the so called “extramontane basins” (Gaitzsch, 1995). At the Lower/Upper Rotliegend transition, the Saalian movements by about 290 to 285 Ma were linked to increased volcanism and tectonic activities. The Oberhof Volcanite Complex of the Thuringian Forest basin, the Donnersberg volcanites of the Saar-Nahe basin, the Planitz volcanites of the Erzgebirge basin, and the upper part of the North German Volcanite Complex all formed at this time (Schneider et al., 1995; Roscher & Schneider, 2005). Mostly strong erosional hiatuses occur around the Lower/Upper Rotliegend transition, after which pure red beds were deposited during the Upper Rotliegend I, in contrast to the interbeddings of grey and red sediments in the foregoing late Lower Rotliegend. At the onset of the Upper Rotliegend II, thermal subsidence accompanied by extrusions of rift-related basalts led to the formation of the North German-Polish basin, heralding the embryonic stage of the Mesozoic/Cenozoic Central European basin (Gebhardt et al., 1991; Schneider & Gebhardt, 1993). This basin and the peneplained areas to its south, i.e., the Rheno-Hercynian Zone, the Mid-German Crystalline Zone, and the northern part of the Saxo-Thuringian Zone, were suddenly flooded by the Zechstein Sea. Reef sediments and sabkha deposits of the first Zechstein cycle directly on Variscan metamorphic and magmatic rocks and on Rotliegend volcanites, which earlier had represented erosional areas to the Rotliegend basins, indicate that the Variscan morphogene was nearly levelled during late Upper Rotliegend.

Fig. 45. Overlook on the development of the basins described in the text; added for comparison are the profiles of the Mississippian to Pennsylvanian Variscan foredeep in North Germany as well as of the North German Volcanite Complex and the Southern Permian basin. Intrusive granite bodies are marked with crosses, levels of intense volcanism with v. From Schneider & Romer (2010) based on Schneider (2001) and Roscher & Schneider (2005). Note that the boundary between Stephanian and Lower Rotliegend is set now at 300 Ma, and the boundaries of stages have changed since Biostratigraphic age control of the basin 2010 – for the present positions see Fig. 4 and Fig. 5. evolution

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The fast economic expansion during the 18th and 19th centuries in Central Europe was based on the rapidly increasing exploitation of ore and coal deposits, which in turn led to ambitious mapping programs of the territories (geologische Landesaufnahme) at the scale 1: 25.000. The first detailed lithostratigraphical subdivisions date back to this time. Interestingly, the definition of the terminus “Formation” given by Cotta (1856, 1878) is nearly identical with the actual use. Many of the formation names given by Weiss (1889) for the Saar-Nahe basin and by Beyschlag (1895) for the Thuringian Forest basin, are still in use. Very early, plant fossils have been used for the characterization and correlation of coal bearing sequences, as shown by the voluminous and richly illustrated descriptions of floras of the Carboniferous “Steinkohlengebirge” and the Permian “Rothliegend” by Schlotheim (1804), Sternberg (1820), Göppert (1836), Geinitz (1854a), Weiss (1876), and Potonié (1893). Geinitz (1856), based on his six “vegetation belts”, made the first attempts for interregional biostratigraphic correlation. Modern revisions, especially of Rotliegend floras, were published by Barthel (e.g., 1976, 2003) and Kerp (e.g., Kerp & Fichter, 1985; Kerp & Haubold, 1988), but now increasingly under palaeo-ecological aspects (Kerp, 2000). Macrofloras and palynomorphs are still in use for non-marine Carboniferous biostratigraphy (e.g., Clayton et al., 1978; Cleal & Thomas, 1996), but are considered to be increasingly problematic in the Permian biostratigraphy (e.g., Broutin et al., 1990; DiMichele et al., 1996, 2001; Kerp, 1996).

Fig. 46. Spiloblattinid (cockroach) insect zonation based on lineages of the above indicated 3 genera and their chronospecies; wing pairs show sexual dimorphs so far known. The zonation is calibrated to the global marine scale by isotopic ages and co-occurrences of insect zone species with marine zone fossils as conodonts and fusulinids in North America and the Donets basin. For details see Schneider & Werneburg (2006, 2012); Schneider et al. (2013).

Following the early compilations on Rotliegend animal fossils (e.g., Geinitz, 1861), Weiss (1864) attempted for the first time to use fossil animals to correlate Rotliegend sediments biostratigraphically. Initiated by demands of natural gas exploration in Pennsylvanian and Permian deposits of Europe in the 20th century, different biostratigraphic tools were developed for diverse environments and different litho- and biofacies pattern (for details see Schneider, 2001; Roscher & Schneider, 2005). They include in particular the conchostracan (Spinicaudata) zonation (e.g., Martens, 1983, 1984; Schneider et al., 2005) and the higher resolving insect zonation for the Middle Bashkirian (Westphalian A, Early Pennsylvanian) to the Artinskian (lower Upper Rotliegend, Late Cisuralian; Schneider et al., 2005; Schneider & Werneburg, 2006; Fig. 46). From the Late Moscovian (Westphalian D) to the Artinskian (lower Upper Rotliegend, Late Cisuralian), the amphibian zonation of Werneburg (1989a, b, 1996) is successfully applied (Werneburg & Schneider, 2006, 2012). Additionally, freshwater shark teeth (Schneider & Zajic, 1994; Schneider et al., 2000), and tetrapod tracks could be used (e.g., Haubold, 1970; Voigt, 2005). Comparable faunal and biostratigraphic investigations were made in the SaarNahe basin (e.g., Boy, 1987; Boy & Fichter, 1982; Hampe, 1989). Detailed palaeobotanical correlations between the basins were problematic as recurring humid phases during the Permian were

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superposed on a general trend to increasingly more arid climate (for a review see Schneider et al., 2006; Roscher & Schneider, 2006). The recurrent humid phases made that Carboniferous hygrophilous floras locally persisted far into the Rotliegend (e.g., Kerp & Fichter, 1985; Broutin et al., 1990; DiMichele et al., 1996), whereas the more arid conditions made that in other basins floras with mesophytic character already occurred in the Permian (e.g., Kerp, 1996; Kerp et al., 2006). In recent years, palaeomagnetic studies (e.g., Menning, 1987, 2006) and isotopic ages have been increasingly combined with biostratigraphic data for regional and interregional correlation and the correlation of continental profiles with the marine global standard scale (e.g., Lützner et al., 2007; Roscher & Schneider, 2005; Davydov et al., 2010; Schneider & Werneburg, 2012; Schneider et al., 2013).

2. The Carboniferous – Permian Erzgebirge Basin The present-day 70 km by 30 km large and NE-SW striking Erzgebirge basin in south Saxony (Fig. 47) was discontinuously filled with the molasses of the Variscan orogen (Fig. 45). Sedimentation was interrupted by long periods of non-sedimentation and erosion of older basin fill. Subsequent basins were controlled by different geodynamic regimes and, therefore, had a development independent of their precursors. The term Erzgebirge basin includes the entity of these subsequent basins as it describes the present-day distribution of Late Palaeozoic deposits at the northern flank of the Erzgebirge, rather than a specific basin in geotectonic terms. The Late Visean is represented by relicts of the Hainichen basin (see Gaitzsch et al., 2008). At intersections of deep faults, local basins developed, such as the postorogenic basins of Flöha (Westphalian B/C; Duckmantian/Bolsovian) and the Oelsnitz and Zwickau basins (Westphalian D ?Cantabrian). Erosional relicts of additional Westphalian basins exist in the Eastern Erzgebirge, e.g., the B/C Olbernhau-Brandov and B-D Schönfeld-Altenberg basins (Fig. 47). The Rotliegend Chemnitz basin developed after the Franconian volcano-tectonic movements and basin re-organization. It is superimposed on the deep-reaching detachment between the Erzgebirge and the Saxon Granulite Massif (Fischer, 1991; Kroner, 1995). Basin development and configuration during the Lower Rotliegend and Upper Rotliegend I was mainly controlled by volcano-tectonic processes. Starting with the Upper Rotliegend II, facies patterns follows increasingly NW-SE directions. The Middle to Late Permian red beds of the Mülsen Formation form the transition to the Late Permian Zechstein and Mesozoic platform development (Fig. 45). In the northwestern part of the Chemnitz basin, these Upper Rotliegend coarse clastic sediments are transgressively overlain by marine Zechstein deposits and their terrestrial equivalents.

Fig. 47. Map of the Saxon basins; A – primary extend of the Westphalian D Zwickau-Oelsnitz basin, B – erosional remnant of the Zwickau subbasin, C – remnant of the Oelsnitz subbasin, D – Westphalian B/C Flöha basin, E – remnants of the Visean Hainichen basin, F – remnants of the Westphalian B/C and Permian Olbernhau-Brandov basin; G – remnants of the Westphalian B-D Schönfeld-Altenberg basin, R – Reinsdorf fan and M – Mülsen fan, Zwickau subbasin. Thick line around the Erzgebirge basin marks the actual extend of the Rotliegend Chemnitz basin.

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2.1 The Early Permian Chemnitz Basin The Rotliegend of the Chemnitz basin is world-famous for its Permian petrified forest. The often colourfully silicified tree trunks have attracted the Saxon electors for their splendid collections of jewellery and gem stones. Special officials, the gemstone inspectors, searched the country for such “noble stones”. One of them was David Frenzel from Chemnitz. From 1740 onward he discovered several large petrified trunks in Chemnitz-Hilbersdorf, which he transported to the Saxon capital Dresden, where they were processed into beautiful works of art, exposed in the “Grünes Gewölbe” in Dresden (Rößler, 2001). In the early years of the scientific palaeobotany in the first half of the 19th century, the descriptions of this silicified wood have stimulated the study of three-dimensionally preserved plant fossils in general. Geinitz´s (1858) publication on plant guide-fossils of the Permian of Saxony is one of the first attempts in plant-biostratigraphy and was directly linked to the demands of the geological mapping of Saxony.

Fig. 48. Geological map of the Permian Rotliegend of the Chemnitz basin (after Schneider et al., 2012).

Development and basin fill of the Rotliegend Chemnitz basin (Fig. 48, 49) The Rotliegend Chemnitz basin arose after the Franconian movements and basin reorganization, and is superimposed on the deep fault system of the detachment between the Erzgebirge Mountains and the Saxonian Granulite Massif. Deposits of the Rotliegend cover the whole basin (Fig. 48), basement areas and coal-bearing successions of the Visean and the Asturian/?Cantabrian were overlain. In the Western part of the basin, the oldest Lower Rotliegend sediments (Härtensdorf Formation) rest with an angular unconformity on the deeply eroded upper Zwickau Formation of topmost Westphalian to Cantabrian age. This erosional gap could be related to the Franconian movements at the Stephanian/Rotliegend transition but also to the preceding Asturian movements during or after the Cantabrian as well. Basin development and configuration during the Lower Rotliegend is mainly controlled by volcano-tectonic processes. Frequent ash falls during this time originate from volcanic activity mostly outside the basin, possibly in the NW-Saxony Volcanite Complex, which confines the basin to the North. Starting with the Upper Rotliegend II, facies patterns follow increasingly NW-SE directions perpendicular to the Variscan strike. The Middle to Upper Permian red beds of the Mülsen Formation formed possibly the transition to the Late Permian Zechstein and Mesozoic platform development. In the NW of the Chemnitz Basin this Upper Rotliegend coarse clastics are covered transgressively by marine Zechstein deposits and their terrestrial equivalents.

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The up to 1550 m thick basin fill of the Chemnitz basin (70 km x 30 km) consists mainly of alluvial red beds and volcanites and is subdivided in four formations (Fischer, 1990; Schneider et al., 2012). The oldest one, the 180 m (max. 280 m) thick Härtensdorf Formation, deposited in a WSW-ENE to SWNE orientated basin, shows basal matrix-supported fan conglomerates. These coarse clastic deposits were formed by debris flows that interfinger towards the basin centre with fine-clastic alluvial and flood plain sediments, mainly siltstones with intercalated channel conglomerates of a braided river system. The often greenish to light grey coloured fills of those channels point on palaeo-groundwater flow. Flood plain deposits contain sporadically centimetre to decimetre thick coal seams of local swamps. Very typical for the flood plain siltstones and silty sandstones are invertebrate burrows of Scoyeniatype. Common are calcareous rhizoconcretions in the neighbourhood of the channels and stacked calcisols of different maturity. Decimetre thick micritic limestones with mm-sized gastropods and minute isolated skeletal remains of snake-like aistopod amphibians indicate the existence of temporary pools and lakes (Schneider & Rößler, 1996). The age of the Härtensdorf Formation is determined by macrofloral remains (such as Alethopteris schneideri, Callipteridium gigas; Barthel, 1976) as Lower Rotliegend and by sporomorphs as late Asselian based on the dominance of Vittatina spp. (Döring et al., 1999). Volcanism started in the upper Härtensdorf Formation with pyroclastic horizons due to plinian eruptions and continued into the Planitz Formation which was dominated by extended volcanic deposits.

Fig. 49. Stratigraphy and fossil content of the Early Permian Chemnitz basin (after Schneider et al., 2012).

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The base of the up to 170 m thick Planitz Formation is marked by the 5 to 25 m thick Grüna tuff. This formation mainly consists of different volcanites, like ash tuffs and ignimbrites and their reworked products as well. Depending on the position to the eruption areas inside and outside the NW-Saxony basin, there are regional changes in thickness and facies pattern, although several tuff horizons form excellent marker horizons throughout the basin. Intercalations of conglomerates, sandstones, and siltstones are subordinate. The Grüna pyroclastic rocks are directly overlain by the distinctive Niederplanitz lake horizon, which represents a vertical and lateral sequence of centimetre to decimetre thick lacustrine black, greenish-grey to red claystones and siltstones with intercalated pyroclastics. These deposits formed during a wet climatic phase in an extended lake landscape. The low diversity vertebrate fauna only consists of palaeoniscid fishes and xenacanthid fresh water sharks indicating the linkage of this basin to a larger, interregional drainage system, enabling the immigration of fishes. Flows of trachybasaltic and shoshonitic lavas of up to 70 m thickness originated from different fault controlled eruption centres in the south-western part of the basin. The upper part of the Planitz Formation contains widespread ignimbrites, locally deposited as vitrophyres (pitchstone). The age of the Planitz Formation is determined as late Lower Rotliegend (late Asselian/early Sakmarian) by xenacanthid shark teeth (Schneider, 1988); sporomorphs indicate a late Autunian age, comparable to the late Asselian of the Donetsk basin (Döring et al., 1999). The up to 700 m thick Leukersdorf Formation rests erosive on the Planitz Formation. Decametre thick basal conglomerates contain the debris of the eroded Planitz volcanites. Generally, the formation consists of red fan and predominating alluvial to flood plain deposits in three fining-up cycles. Alluvial and flood plain deposits are characterised by the Scoyenia facies of wet red beds as well as calcisols of different maturity. Apart from common tiny rootlets this formation basinwide rarely shows any evidence of plant growth. In this respect, the Chemnitz fossil forest is an unusual, very local assemblage with a rich forest flora and fauna. The top of the first cycle is formed by the maximally 25 m thick fluvial-palustrine Rottluff horizon, consisting of grey clastics with plant remains and thin coaly layers. The top of the second cycle is marked by several thin limestone beds of the Reinsdorf lake horizon. This grey micritic limestone contains gastropods, ostracods, and rarely disarticulated tetrapod remains. Very rarely, laminites delivered poorly preserved branchiosaurid amphibian skeletons. The third cycle is marked by the eruption of the up to 90 m thick Zeisigwald tuff. As rhyolithic volcanism occurred on a widespread scale during the Early Permian, this eruption series particularly influenced the eastern part of the basin. In the area of present-day Chemnitz the eruption of the Zeisigwald volcano additionally resulted in the formation of the Chemnitz Petrified Forest. The initial blast of a phreatomagmatic eruption cut the majority of up to 30 m high woody trees. The latter were laid down in east-west direction and covered by different pyroclastics (Fischer, 1991; Rößler, 2001). The absolute age of this volcanic event of about 290.6±1.8 Ma was recently determined by SHRIMP U-Pb measurements on zircons (Rößler et al., 2012), which corresponds to the Asselian/Sakmarian transition. This is supported by a rich palynoflora dominated by the saccate pollen taxa Potonieisporites spp., Florinites ovalis, and Vesicaspora spp., and by Vittatina sp. from the palustrine Rottluff Coal in the lower part of the Leukersdorf Formation (Döring et al., 1999). That association shows great similarities of this stratigraphic level and the late Asselian Slavjanskaja Svita of the Donetsk Basin reference section. Amphibian remains of the Melanerpeton pusillum – Melanerpeton gracile-Zone indicate a position in the European highest Lower Rotliegend (Werneburg & Schneider, 2006; Schneider & Werneburg, 2012). The following Mülsen Formation is separated from the Leukersdorf Formation by a long lasting hiatus and may reach up to 400 m in thickness. This formation completely consists of red fanglomeratic conglomerates, sandstones, and siltstones deposited in a debris flow/sheet flood dominated fan and alluvial plain environment. Nodular dolocretes are common. Well-rounded coarse sand grains, in places concentrated in the matrix of the fanglomerates, and strips of well-sorted fine to medium sand indicate reworked aeolian deposits. The fossil content is restricted to rare invertebrate burrows and very sparse and tiny root structures. Based on facies patterns, palaeoclimatic considerations, and the relationship to the overlying continental equivalents of near shore marine Zechstein deposits, an Upperrotliegend II (late Guadalupian to earliest Lopingian) age is estimated. Most probably, the Mülsen Formation forms the transition between the post-orogenic Variscan molasses and the platform sedimentation of the Zechstein.

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The Permian Petrified Forest of Chemnitz – general information Leukersdorf Formation Thickness: up to 700 m Base: basal conglomerates erosive on Planitz Formation Top: basal conglomerates of the Mülsen Formation Biostratigraphy: Early Permian Rotliegend after macrofloral remains (Barthel, 1976); lowermost Leukersdorf Formation – sporomorph associations indicative for sporomorph zone XVI, level S4 (uppermost Slavjanskaja Svita) of the des Donetsk basin, latest Asselian (Döring et al., 1999). The amphibian Onchiodon permits after Werneburg (1993, 1995a,b) the comparison with the Niederhäslich Formation of the Döhlen basin and the Oberhof Formation of the Thuringian Forest – uppermost Lower Rotliegend. Isotopic age: 290.6±1.8 Ma, SHRIMP U-Pb of zircons (Rößler et al., 2012), Sakmarian/Artinskian transition. Lithology/facies: wet red beds of an alluvial fan/alluvial plain/lake system, minor fluvial-palustrinelacustrine deposits close to the base (Rottluff horizon), one nearly basin wide lake horizon in the middle part (Reinsdorf horizon), some pyroclastic horizons and in the Western part of the basin the marker horizon of the Zeisigwald caldera eruption. Fossil content of the red beds: very common endogenous ichnia of Scoyenia- and Planolites montanus-type; one amphibian skeleton (Onchiodon) and some vertebrae of an diatectomorph cotylosaur (Phanerosaurus naumanni); vertebrate microremains and bad preserved branchiosaur skeletons in the Reinsdorf-limestone horizon together with characean gyroconites, ostracods and gastropods; rare macro flora remains (walchians) in the red beds; but see stop 8 – the Petrified Forest of Chemnitz for his richness in plant and animal fossil (Rößler et al., 2012). There, depending on local edaphic conditions and the position of the groundwater level, the rich flora consists of hygrophilous associations and meso- to xerophilous associations as well. Palaeoclimate: Wet red beds of the Scoyenia-Planolites montanus-ichnofacies, common vertisols and calcisols with calcretes, and the predominance of the meso- to xerophilous walchians point on semihumid seasonal climate with pronounced dry phases. The widespread Reinsdorf lake horizon, frequently accompanied by coarser channel deposits, belongs to the Late Sakmarian/Early Artinskian wet phase D of Roscher & Schneider (2006). The recurrence of hygrophilous floral elements in the Chemnitz Petrified Forest is a local exception, a “wet spot” in the sense of the “refugial model” of DiMichele et al. (2010), caused by a locally unusual high groundwater level. Nevertheless, growth rings of trees in the Petrified Forest also support climatic seasonality. The wet red beds of the Leukersdorf Formation (Fig. 49) were deposited in front of semi-arid type alluvial fans. Coarse clastics of intense ephemeral flood discharge are dominated by mass-flow deposits and interbedded sheet floods. The latter one was largely maintained by the high contend of clay matrix, which was derived from the low-grade metamorphic source areas (e.g. Berga swell). Alluvial plain silty to sandy fine clastics are intersected by conglomerates of shallow braided river channels. The Scoyenia-ichnofacies of siltstones as well as completely bioturbated sandy, mica-rich siltstones of the Planolites montanus-ichnofacies are very characteristic for temporary relatively high groundwater levels (in contrast to playa environments). Vertisols are common; root penetration of various degrees connected with colour mottling is widespread. Millimetre-fine branched root systems are common on bedding plains. In the neighbourhood of former palaeo-groundwater conducting and therefore whitish-greenish leached coarse clastics, calcic soils are developed. They consist of carbonate nodules from millimetre to decimetre scale as well as of nodular micritic calcrete horizons of decimetre thickness. Vertical oriented subcylindrical to conical rhizoliths of 1.5 to 10 cm diameter and up to 60 cm length are not rare. Cross sections of this roots show often a distinct concentric zonation: first a central root mould filled with sparry calcite, second a micritic envelope with alveolar-septal fabric from small lateral roots or root hairs and at least an outer zone of pale green calcite-cemented sediment. Generally, the low maturity of the calcic soils indicates high aggradation rates. The Permian Petrified Forest of Chemnitz – description of excavation sites In fossil forests ancient trees from the geological past have been fossilized in growth position. One of these fossil forests is known from Chemnitz, Germany, where an Early Permian landscape was buried instantaneously by volcanic deposits, preserving autochthonous and parautochthonous fossil assemblages (Sterzel, 1875; Barthel, 1976; Rößler, 2001). What makes this fossil lagerstätte so

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special in comparison to other fossil forests with tree stumps preserved in situ is the historical importance of the Chemnitz fossil forest. Collecting at this site dates back to the early 18th century, and many collections worldwide house exhibition-quality specimens from the Chemnitz fossil forest. The often colorfully petrified tree trunks have attracted the Saxon electors for their splendid collections of jewelry and gemstones. Special officials, the gem stone inspectors, searched throughout the country for such “precious stones”. Later, specimens from this site provided the basis for introduction of fossil plant names reaching back to the early days of palaeobotany. Several genera of common late Palaeozoic plants were first described from Chemnitz, type locality of Psaronius, Tubicaulis, Calamitea, and Medullosa (Cotta, 1832). The majority of finds was made in the late 19th and early 20th centuries, when residential areas were build. Since the 1990s many new specimens have been recovered during construction works, but all of them were unintentional, because most of the fossil forest has been developed into an urban area. Hence, the possibility of reconstructing both whole plants and the palaeoenvironment in which they grew was limited. Based on accidental finds and on specimens from historical collections, the Chemnitz fossil lagerstätte has been re-investigated in the last decade. First scientific excavation (2008–2011) The Museum für Naturkunde Chemnitz carried out a systematic and well-documented scientific excavation of this fossil forest for three and a half years within the city limits of Chemnitz (50°51'58.68" N, 12°57'32.54" E). The excavation site is one of the very few remaining areas that has not been disturbed by building activities and, thus, offered a unique chance to study the fossil forest in situ. Specific objectives of the excavation were to find evidence for connections of organs in the Chemnitz plants, and to record coordinates in three-dimensional space for each find, enabling 3D reconstructions of the excavation site (e.g., Fig. 54), the unearthed plant fossils, and the plant community. In addition, we aimed to investigate the volcanic and sedimentary rocks in the outcrop area to acquire a clearer understanding of the volcanic events and how they affected the ecosystem. Preliminary data consist of a large number of exceptional finds, 3D coordinates, and detailed field observations (Kretzschmar et al., 2008; Rößler et al., 2009, 2010, 2012). Unique features that have been documented here for the first time are: (1) the presence of rooting structures of several taxa that are preserved in situ in a single horizon, (2) the occurrence of foliage and reproductive organs associated with petrified stems and branches, and (3) the presence of various animal remains found together with the plants, including reptiles still showing the original body outlines (Fig. 52). The site is located in the middle of a residential area, but fortunately older anthropogenic influences could be excluded in the excavation area. The dimensions of the excavated area were 24 m by 18 m, and a depth of at least 5 m, which left ca. 130 m2 at the bottom of the pit. A huge number of data and specimens was recovered. In all, about 860 collection boxes were filled with 630 petrified trunks and isolated branches of various plant groups. In total, 53 trunks still standing upright in growth position were found. In addition, about 1,200 adpressions of associated megafloral and megafaunal fossils and 635 rock samples for future sedimentological, geochemical, and volcanological studies were collected, recorded, and measured in three dimensions. Section at the excavation Chemnitz-Hilbersdorf (Fig. 50) The excavated section comprises of the lower part of the Zeisigwald tuff horizon and its sedimentary basement (Fig. 50). It has been divided into six units (S1–S6, see Fig. 50). Unit S5 is further subdivided into four distinct lithofacies (LF5/1–LF5/4). The description excludes Units S1 and S2 that represent the recent soil horizon overlying weathered run-off hill scree with scattered log fragments and extending down to approximately 1.3 m depth. The geological section was documented in-depth, and thereby taphonomic phenomena were detected, such as fluid-escape structures, bleaching haloes, catchment areas rich in woody branches, large pyroclasts, and patterns that reveal transport directions. Unit S6 is interpreted as an alluvial palaeosol, as indicated by a set of diagnostic criteria for soil formation. The most conspicuous feature is the common presence of roots in different forms of

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Fig. 50. Simplified profile of the Zeisigwald pyroclastic sequence from the caldera trough different outcrops and the profile Hilbersdorf excavation site with typical lithotypes and the fossil content – for details see text. (after Rößler et al., 2012; compiled by L. Ludhardt).

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preservation, intensive colour mottling, and the occurrence of carbonate glaebules of different sizes. The rooting of plants and other processes involved in soil formation (swelling, shrinkage, pedoturbation, various animal activity) have altered or completely destroyed most pre-existing sedimentary structures. A horizon with very large carbonate nodules was recognized 0.8 to 1.0 m below the top surface of Unit S6. This horizon shows a gradational top and base, as well as chert lenses of authigenic silica, and is interpreted as a groundwater calcrete horizon precipitated from the phreatic zone. This palaeosol supported a dense vegetation dominated by hygrophilous elements, but did not develop any peat. As remnants of the primary sediment composition and structures in both the soil horizon and the sediments beneath Unit S6 indicate, soil formation and growth of the forest took place on typical Leukersdorf Formation red beds. Deposition was dominantly by suspension, in places also with minor bedload of sandy-pebbly braided river channels, and caused a multistacked, finegrained deposit in a distal floodplain environment. Complete root systems of the tree fern Psaronius, the calamitalean Arthropitys, and the gymnosperms Medullosa and Cordaixylon can be studied and compared for the first time from a single horizon in the Permian. Although these plant groups colonized the same environment and grew closely associated, they show differences in their root types and habitat adaptations. Whereas the sphenophyte Arthropitys had a system of woody adventitious (secondary) roots attached at an angle to its thickened stem base and the tree fern Psaronius shows a trunk completely enclosed by a downwardly thickening mantle of adventitious roots, the gymnosperms have orthotropic tap roots with plagiotropic lateral roots and associated fine capillary root masses. Detailed analysis of the different root systems will provide a more sophisticated understanding of their habitat preferences and of the physiology and autecology of the parent plants. Unit S5 represents a half meter succession of ash-tuffs and lapilli stones that may have resulted from low-concentration pyroclastic density currents and accompanying fallout that was caused by an explosive magmatic to phreatomagmatic eruption with pulses of activity and a general increase in intensity. The thin but distinctive lithified Unit S4 clearly indicates increasing phreatomagmatic influence. The deposit contains shards showing shapes typical of both explosive magmatic and phreatomagmatic fragmentation processes. An increase in the occurrence of accretionary lapilli accounts for the presence of suspended ash and moisture in the eruption cloud. Accretionary lapilli are commonly present in ash grain-size fall deposits, and the considerable portion of broken accretionary lapilli could point to a fall deposit like an ash cloud that often accompanies pyroclastic flows. The sum of textural characteristics, such as poor sorting and variation in thickness of the unit, however, also argues for a deposit that resulted from a low-concentration pyroclastic density current. The sum of features recognizable at the top of Unit S4 shows that the ecosystem was nearly destroyed during its deposition. Only a few large trees extended into Unit S3 and, therefore, resisted the depositional processes up to this stage. Unit S3 is interpreted as a primary pyroclastic flow deposit with a high concentration of particles resulting from a phreatomagmatic eruption. This is evidenced by a variety of criteria that characterize deposits of high-concentration pyroclastic density currents (Druitt, 1998; Branney & Kokelaar, 2002). Unit S3 shows textural characteristics as poor sorting and reaches from massive to graded and diffusely stratified layers with a sharply defined erosive base. Additionally, the rock exhibits multiple indications of directional flow. In some cases, the buckling of branches is exceptionally well preserved. Tree trunks and branches are frequently broken off, and, if still attached, they are preserved with their apices pointing westward. Whereas the basal part of this unit bears small-sized stems and branches, the axes become larger in diameter toward the upper part. Primary hot emplacement is indicated by fluid-escape structures frequently observed above tree trunks, indicating heat-mobilized fluids arising from the plant tissues. Fluid mobilization from the trees may also be underlined by the grain-size distribution and geochemical behaviour along the upward directed escape structures. Another distinctive pattern that reveals the distribution of the former plant’s fluids into the sediment is seen in the frequently occurring bleached zones close to the petrified stems and branches. In 3D space, mushroom-shaped, bleached areas outline the petrified trunks and branches, and commonly widen in the space above them (Fig. 54). In addition, preliminary results from the geochemical composition of the tuff matrix indicate some kind of autometasomatic reactions in the upper periphery of the fluid delivering stems or branches and most likely point to an authigenic hydrothermal alteration. Cortex preservation in the woody plants is rather rare, since the periphery of their stems seems to be strongly affected by the hot ignimbrite. In the lowermost centimetres of Unit S3, close to the top of Unit S4, many small, upright plant axes are abruptly truncated, because they were cut by the shearing power of the emplacing Unit S3 density current.

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Fig. 51. Preservation diversity of cordaitaleans at the excavation. A) Cordaixylon trunk with attached branches up to 3 m long embedded in the Unit S3 pyroclastic flow deposit (KH0021). B) Gymnosperm trunks in the northernmost part of the excavation area, the one in front is still in situ standing (KH0004), the one behind lies horizontally in the Unit S3 ignimbrite (KH0025). Scale bar 1 m. C) Cordaixylon stem with attached branches. Surface sand-blasted (KH0073). Scale bar 20 cm. D) Detail of the specimen shown in Fig. 51C with branch traces. Scale bar 4 cm.

Fossil record The autochthonous fossil deposit originated from volcanic eruptions and preserved the most complete Permian forest ecosystem known to date (Fig. 51, 52). Fifty-three trunk bases, still standing upright in their place of growth and rooting in the underlying palaeosol, characterize this fossil lagerstätte as a significant T0 assemblage (DiMichele & Falcon-Lang, 2011). This “window” gives insights into a spatially restricted lowland environment that sheltered a dense hygrophilous vegetation of pteridophytes and gymnosperms as well as a diverse fauna of vertebrates, arthropods and gastropods. The majority of the most instructive excavation finds are petrified trunks, axes, and branches of various orders of branching. They are mostly silicified or preserved by purple calcium fluoride, rarely calcified, and give us 3D insight into the cellular detail of arborescent plants and their organs. Among them are psaroniaceous tree ferns that until now are exclusively those of the distichous branching type, calamitaleans of the Arthropitys wood type, medullosan seed ferns with a conspicuous anatomical diversity and gymnosperms of cordaitalean affinity. Many of the 53 aforementioned specimens represent basal stem portions of different sizes that are still standing upright in their growth positions and rooted in the underlying palaeosol. The most complete and significant preservation of petrified material was traced in Unit S3. An exceptionally large calamite bears a crown that is repeatedly branched and estimated to have been at least 15 m in height with at least three orders of secondary woody appendages. This is the first time that the branching architecture of an anatomically preserved calamite tree is clearly discernible in three dimensions (Feng et al., 2012). Although petrifactions are more likely to be poorly preserved in both the Units S4 and S5, palaeosol Unit S6 contains many well-preserved, silicified remains, which include both upright in situ rooted tree bases and horizontally positioned deadwood logs. During an early stage of volcanic activity, volcanic ashes were deposited and covered the standing vegetation. As a result, many trees shed their leaves, which are found embedded in a fine-grained ash-tuff layer near the basis of Unit S5, Facies 5.1. Since the plant fossils are exclusively adpressed in the tuff, organic remains are lacking.

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We, therefore, have neither a classical compression flora nor an impression flora. In contrast to the latter, our fossil material additionally reveals 3D aspects to some degree. Collecting and detailed analysis of the first fallout and flow deposits represented by the different facies of Unit S5, not only provided a rich plant assemblage. Along with leafy shoots, pinnate fronds, detached whole and fragmentary leaves, the leaf horizon has yielded the first outstanding faunal remains. A diverse fauna of vertebrates, arthropods, and gastropods was discovered for the first time from this site and will enable a more comprehensive view of this fossil lagerstätte. The faunal remains include such vertebrates as several reptile skeletons, aistopod microsaurians, and remains of an eryopid amphibian, as well as such invertebrates as diplopods, Arthropleura remains, various arachnids like a whip scorpion, and trigonotarbids (Fig. 52).

Fig. 52. Diversity of the animal fossil record. A) Diplopod impression in the tuff of Facies 5.1 (TA0851). Scale bar 7 mm. B) Trigonotarbid arachnid from the tuff of Facies 5.1 (TA0932). Scale bar 3 mm. C) Pulmonate scorpion found in the uppermost palaeosol (TA1126). Scale bar 1 cm. D) Leg of the giant millipede Arthropleura (TA0884). Scale bar 1 cm. E) Aistopod from the tuff of Facies 5.1 (TA0900). Scale bar 1 cm. F) Complete reptile skeleton from the tuff of Facies 5.1 (TA1045). Scale bar 2 cm.

Stop 1: Early Permian Zeisigwald caldera and tuff Stratigraphy: Leukersdorf Formation, Lower Rotliegend, Sakmarian/Artinskian. Location: abandoned quarry Findewirth, eastern border of Chemnitz (Fig. 50, 53). Coordinates: N 50°51’19.0”; E 12°57’56.6”. Isotopic age: 290.6±1.8 Ma, SHRIMP U-Pb of zircons (Rößler et al., 2012), Sakmarian/Artinskian transition. Many historic quarries for local dimension stone and dumps are located in the forested area NE of Chemnitz. Quarrying aimed to mine the Zeisigwald Tuff of the Leukersdorf Formation, which is the youngest Permian pyroclastic unit of the Chemnitz Basin. The tuff rock has been frequently used in architecture and arts since the middle ages. The old quarries and new wells for groundwater protection have exposed the volcanic vent of the tuff, the Zeisigwald Caldera, with a dimension of 2.6 x 1.6 km (Eulenberger et al., 1995). Inside the caldera the deposits reach a thickness of about 90 metres. The pyroclastic succession is subdivided as follows (Fig. 50):  basal crystal-poor tuff of few decimetre thickness (b-horizon),  several meters tuff of air fall origin (a1-horizon),  base surge deposits (s-horizon),  low-grade ignimbrites (ign-horizon) and layers of co-ignimbritic ash falls,  final tuffs of air fall origin (a2-horizon) and  reworked pyroclastic deposits. Accretionary lapilli occur in the s-, ign- and final a-type deposits and reach diameters of almost 3 cm. They occur matrix- to clast-supported and have multiple rims. The nonwelded ignimbrites contain

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pumice fragments of up to 30 cm length. Lithic fragments of basement rocks (phyllite, gneiss, micashist, quartz) are locally abundant. In the outcrop, beds and lenses of the surge deposits in the lower part of the quarry show parallel to low angle bedding, whereas the ignimbrite deposits appear massive. The Zeisigwald Tuff is geochemically characterized by elevated contents of Be, Sn, F, Li and low contents of Zr. Fluorite petrified parts of the embedded wood fragments as well as selected portions of the tuff itself (e.g. pumice fragments). This eruption destroyed and preserved the unique Chemnitz Petrified Forest. In the city area, the tops of the buried trees point to the W, as is shown by many documented findings. This observation supports the location of the vent in the Zeisigwald area.

Fig. 53. Abandoned Zeisigwald tuff rock quarry Findewirth at the Eastern border of Chemnitz; anti-dune bedding of the base surge deposits of the eruption; Upper Leukersdorf Formation (Sakmarian/Artinskian).

Stop 2: “Window to the past”, excavation Sonnenberg, Zeisigwald tuff Stratigraphy: Leukersdorf Formation, Lower Rotliegend, Sakmarian/Artinskian. Location: Chemnitz, Sonnenberg, Glocken-Str. 16. Coordinates: N 50° 50.141'; E 12° 56.055'. Starting in the 2nd half of the 19th century, Chemnitz – as many industrial centres in Germany – experienced a rapid growth. Besides Hilbersdorf in the quarter Sonnenberg plenty of petrified tree trunks were found during the urbanisation and railway construction works, since the Zeisigwald Tuff crops out in this area. Nowadays, only few locations in the city remained undisturbed. One of these is the location of Stop 2. First exploration activities were performed in 2009. The excavation started in summer 2012 and will be continued during the next years. The aim of the project is to investigate the basal part of the Zeisigwald Tuff, which hosts the Petrified Forest. The base of the pyroclastic succession has been located in about 2 m depth by drilling and geophysical research. Now several trunks have been located, at least some still standing in growth position. With the current excavation project the museum aims to:

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(1) Increase the public awareness of the Petrified Forest of Chemnitz and get in touch with more people interested in the improvement of the city and the region. (2) The excavation site supports the study of late Palaeozoic plants in the fossil-bearing Permian sequence of Chemnitz as the sites of plant growth and burial are largely identical. (3) The fossil record reveal unknown biological features such as organ connections, ontogenetic variability, the branching architecture and root systems of the occurring arboreal plants. (4) Since the fossil-bearing horizons can be attributed to short time volcanic processes, the findings enhance our understanding of plant’s response to environmental perturbations and enable us to visualize and reconstruct individual volcanic events and their effects on the ecosystem. (5) In comparison with recent volcanic events analogies can be drawn to explain the volcanic processes, and to interpret the taphonomic conditions.

Fig. 54. Three-dimensional model showing excavated stems and branches and the spatial extension of the bleaching haloes surrounding the permineralizations (courtesy of Volker Annacker).

Stop 3: Museum of Natural Science Chemnitz (Fig. 55) Stratigraphy: Holocene, 1868 to present. Location: DAStietz, Moritzstr. 20, Chemnitz. Coordinates: N 50°49’51.22”; E 12°29’51.77”. The history of the museum started in the middle of the 19th century with a circle of citizens being interested in natural science in general. In 1859 they founded the Naturwissenschaftlicher Leseverein‘ (renamed into ‘Naturwissenschaftliche Gesellschaft‘ in 1861). Besides common reading of scientific literature, the primary objectives were to create natural history collections and to build up a scientific library. In 1868 these collections were handed over to the City of Chemnitz on condition of soon public access. This was the birth of the oldest museum in Chemnitz. In 1876 the rapidly increasing inventory was made accessible for the public the first time in an exhibition in the Kunsthütte. With the completion of the King-Albert-Museum in 1909, the Municipal Natural History Collections moved into this museum building close at the Theaterplatz. In 1961 the collections were renamed into ‘Museum für Naturkunde’. After 95 years in the King-Albert-Museum, were the storage capacity finally exceeded, the Museum established his new base in the former TIETZ department store in 2004. As already embedded in the original conception from 1868, the museum is also a centre for scientific education. An increased awareness at the beginning of the 21st century awakes the wish to understand the diversity of our natural environment and to conserve it for future generations. With activities accompanying exhibitions, manifold events, talks and excursions, the museum understands itself as a meeting point in the area of tension between the desire for a higher quality of living and the

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conservation of natural resources. Many committed hobby researchers support the museum in expanding and developing its collections, by providing their knowledge in several environmental education projects as well as in topics like culture, industry and science. The main permanent exhibition – the Sterzeleanum – deals with the Chemnitz Petrified Forest. The international reputation of the museum mainly results from its unique collection of petrified wood.

Fig. 55. Petrified tree trunks in the entrance hall to the Museum für Naturkunde and the Sterzeleanum exhibition of the Petrified Forest of Chemnitz.

3. The Permian Gera Basin Introduction During Rotliegend times the Gera basin forms a western subbasin of the Chemnitz basin separated from the latter by the about 15 km wide Berga swell. Sedimentation starts on Variscian basement, i.e. folded Early Carboniferous marine turbidite sequences. Basin fill consists of the 180 m thick wet red beds of the Creschwitz Formation, an equivalent of the Leukersdorf Formation in the Chemnitz basin, as well of the up to 350 m thick silty, sandy and conglomeratic red beds of the Gera Formation, an equivalent of the Mülsen Formation in the Chemnitz basin. During the marine Zechstein the area of Gera forms a bay at the southern coast of the transgressing sea.

Stop 4: Märzenberg, classical outcrop of the Zechstein transgression sediments (Figs. 56, 57) Stratigraphy: Upper Rotliegend II, Gera Formation (Guadalupian/Lopingian), transgressively covered by marine Zechstein deposits of the Werra Formation (Early Wuchiapingian). Location: Gera-Milbitz, Schiefergasse at the Märzenberg hill. Coordinates: N 51° 53.966´; E 11° 3.310´. Isotopic ages: Kupferschiefer black-shale dated by Brauns et al. (2003) at 257.3±2.6 Ma.

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Biostratigraphy: Mesogondolella britannica from the Kupferschiefer equivalent in the Southern North Sea (Legler et al., 2005) points on a Wuchiapingian age for the basal Zechstein deposits. Lithology/facies: Exposed are up to 10 m of the uppermost Gera Formation consisting of interbeddings of fanglomerates with hyperconcentrated debris flows and sandy siltstones of a distal fan to braid plain environment. Bedding is indistinct; long axes of the pebbles mostly horizontal arranged. Pebble size increases in the top and channel like structures appear. With indistinct boundary the sediment colour change in the upper part to bluish-grey (1.50 m) and higher up to yellowish-beige (2 m). This secondarily leached part is called the “Grauliegend”. In the transition to the bluish part and inside the bluish part appear horizontal arranged micritic calcrete nodules of centimetre to decimetre size. The Grauliegend part and the upper red part are dissected by nearly regularly in 1.5 to 2 m distance spaced and more than 2.5 m long bluish-grey leached desiccation cracks. With irregular boundary follow the marine Zechstein transgression conglomerate (1 m). Marine deposition is clearly indicated by brachiopods and marine bivalves as well as by bar-like pebble orientation and strongly reduced pelite content. With sudden transition follow the sandy limestone of the Mutterflöz (0.3 m) and above them with sharp lower boundary the Kupferschiefer (0.25 m). The latter one merges into the brachiopod rich Productus bank (0.4 – 1 m). Above follow marlstone – limestone interbeddings of the Werra limestone Member (~ 12 m).

Fig. 56. Classical exposure of continental Rotliegend red beds overlain by the marine Zechstein transgression sediments at Gera-Milbitz, Schiefergasse, Märzenberg hill.

Fossil content (most common only): Zechstein conglomerate: brachiopods Cancrinella germanica, Horridonia horrida, Rhynchopora geinitziana (Fig. 58), Strophalosia leplayi; bivalve Wilkingia mackrothi; plant fragments as centimetre thick trunks. Mutterflöz: typical Zechstein fauna (see Productus bank) but without Neospirifer. Kupferschiefer: plants Pseudovoltzia liebeana, Ullmannia bronnii, Ullmannia frumentaria, Culmitzschia florinii; brachiopods Horridonia, Lingula, Orbiculoidea; bryozoans; isolated fish remains. Productus bank: brachiopods Horridonia horrida, Stenocisma schlotheimi, Dielasma elongatum, Pterospirifer alatus, Strophalosia morrisiana, Streptorhynchus pelargonatus, Spiriferellina cristata, Craspedalosia lamellosa, Dasyalosia goldfussi, Lingula credneri, Orbiculoidea konincki; bryozoans Acanthocladia sp., Rectifenestella retiformis, Kingopora ehrenbergi, Synocladia sp., Dyscritella sp.; ecchinoderms: Cyathocrinites ramosus, Miocidaris keyserlingi.

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Fig. 57. Mutterflöz sandy limestone, Kupferchiefer and rd Productus bank, representing the upper part of the 3 shallowing upward cycle; Gera-Milbitz, Schiefergasse, Märzenberg hill.

Fig. 58. Brachiopod Rhynchopora geinitziana in coarse clastics of the Zechstein conglomerate, Märzenberg at Gera, Schiefergasse.

Discussion and interpretation (see Legler & Schneider, 2013): Despite the long research history (since Geinitz, 1854) of this outcrop and the basal Zechstein sediments with the Kupferschiefer as an economically important copper deposit in Europe in general, the process of the Zechstein transgression is not really well understood. In any case, the Kupferschiefer consists in the deeper parts of the basin generally of three shallowing upward cycles – each cycle starts clayish at the base and ended carbonatic in the top (Rentzsch, 1965). Cyclicity in basal Zechstein deposits also occurs along the basin margins and at intra-basin highs, where Kupferschiefer-equivalent sediments were deposited. In the Gera Bight, an embayment at the southern margin of the Zechstein Sea, a succession of Kupferschiefer and Kupferschiefer equivalent rocks crop out (Fig. 59). Rotliegend alluvial fan deposits are storm-wave reworked at the top, and the basal Zechstein conglomerate contains marine bivalves. Organic carbon-rich, sandy limestone (Mutterflöz) overlies the conglomerate. In the Gera Bight, the Mutterflöz is characterized by an upwards increase in carbonate content. Along the southern margin of the Southern Permian basin (SPB) the Mutterflöz shows varying thicknesses. It passes upwards into Kupferschiefer black shale. The Kupferschiefer is overlain by a bioclastic limestone, the Productus bank. Laterally, the thickness of these coquina beds varies greatly over short distances (few 100s m). The Zechstein carbonate (Ca1) overlies the Productus bank and can be correlated throughout the basin. The Zechstein conglomerate, Mutterflöz and Kupferschiefer are interpreted to have been deposited during the transgressive phase of the Zechstein Sea. They record flooding and successive rise in sea level within the SPB. The Zechstein conglomerate formed above storm-wave base and represents a transgressive lag deposit. Due to rapid initial flooding of the SPB, transgressive lags were not developed in deeper parts of the basin. Deposits in the Gera Bight, close to the basin margin, indicate a transgression leading to wave-reworking of Rotliegend deposits. The transition between storm-wave reworked Zechstein conglomerate and Mutterflöz reflects increasing water depth and deposition below storm-wave base. The organic carbon content of the Mutterflöz indicates dysoxic conditions at the sediment surface. Further rise in sea-level resulted in stagnant anoxic bottom-water conditions and formation of the Kupferschiefer. The Productus bank is interpreted to be deposited as tempestite above storm-wave base; laterally varying thickness reflects preserved topography of storm-wave deposits. Deposition of the Productus bank reflects destratification and mixing of the water column. Most possibly, the transgression profile at the Märzenberg reflect only the third shallowing up cycle of the Kupferschiefer, means, the Zechstein conglomerate at Gera is the equivalent of the clayish part of the basal third Kupferschiefer

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cycle (rising sea level) in deeper parts of the basin and the Productus bank the carbonatic part (falling sea level).

brachiopods

Fig. 59. Kupferschiefer and Kupferschiefer equivalents in the Gera Bight (Gera Märzenberg, Schiefergasse). A, Log through Rotliegend-Zechstein transitional profile; compared to the 3 cycles of the basin center the rd Zechstein conglomerate up to the Productus bank represents at the basin border the 3 cycle only. B, Sample of the sandy carbonate of the Mutterflöz. C, Sample of top Kupferschiefer (lower 7 cm) and the transition into the Productus bank. (From Legler & Schneider, 2013, modified).

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4. The Late Permian – Triassic Thuringian Basin 4.1 The Germanic Triassic 180 years ago, Alberti (1834) recognized Buntsandstein, Muschelkalk and Keuper belong to a single stratigraphic unit, which he called “Trias”. Nowadays, the Buntsandstein, Muschelkalk and Keuper are used in the rank of groups for lithostrartigraphic subdivision of the Triassic in the Germanic Basin (Fig. 60). The base of the Triassic was defined by Alberti (1834) with the base of the Buntsandstein. The Buntsandstein mostly consist of various colored, fine to coarse grained siliciclastics of fluvial, fluviolacustrine or playa lake facies. Prominent interbeddings of oolitic and stromatolitic limestones are characteristic for the Lower Buntsandstein. The oolite limestone horizons have high value for both lithostratigraphic subdivision of the Lower Buntsandstein and regional correlations within the Germanic Basin (e.g., Schulze, 1969; Radzinski, 1999). Generally, the lithofacies of Lower Buntsandstein sections strongly differ, depending on their respective palaeogeographic positions within the Germanic Basin. In more central parts of the basin (e.g., in Saxony-Anhalt) the facies is interpreted as playa lake deposits consisting of fine grained siliciclastics with intercalations of oolitic limestones. The playa lake laterally extended for more than 1000 km and straddles between southern Poland and the North Sea (Fig. 61). From basin central localities towards the basin margins the lithofacies increasingly changes to fluviolacustrine deposits. They mostly consist of fine to coarse grained siliciclastics with occasional occurrences of single ooids as well as dolostones with evaporitic residuals. The sedimentary deposits at the margins of the Germanic Basin (e.g., in Thuringia) are characterized by sandstones and conglomerates, which are interpreted as deposits of fluvial and alluvial facies. The correlations between Lower Buntsandstein profiles in central positions of the Germanic Basin and profiles located in the basin margin are realized by litho-, magneto- and cyclostratigraphy (e.g., Szurlies, 2001). Fine grained siliciclastics in the Lower Buntsandstein yield abundant tool marks and invertebrate trace fossils (Knaust & Hauschke, 2004 a, b). The fauna of the Lower Buntsandstein (Early Triassic) contains conchostracans, ostracods, notostracans, xiphosurans, and tetrapods as well as sparse micro- and macrofloral remains (e.g., Dette, 1930; Kozur & Seidel, 1983; Hauschke & Wilde, 2000; Voigt et al., 2008; Scholze et al., 2012). Additionally, investigations of microfossils from oolitic limestones have delivered actinopterygian teeth and other fish remains (Scholze et al., 2011). For biostratigraphy the conchostracans (Branchiopoda, Crustacea) provide the highest value, because they occur most frequently among all other faunal elements. Prominent occurrences of tetrapod footprints like Chirotherium are characteristic for certain intervals of Middle Buntsandstein (e.g., Klein et al., 2013). In the Upper Buntsandstein the Germanic Basin became increasingly influenced by marine ingressions, which initiate a general change towards fully marine conditions of the Muschelkalk. The Muschelkalk represents the Middle Germanic Triassic. The marine transgressions of the Tethys into the Germanic Basin during the Muschelkalk took place in several phases through marine openings like the East Carpathian, the Burgundian and the Silesian–Moravian gateways at the margins of the Germanic Basin (e.g., Ziegler, 1990). Lithostratigraphically, the Muschelkalk is divided into three subgroups (Fig. 60). The lithology of Lower and Upper Muschelkalk mainly consists of marl and limestones as well as oolites. Dolomitic rocks are most characteristic for the Middle Muschelkalk. The Muschelkalk fauna is rich in ammonites, brachiopods, molluscs, crinoids, conodonts and diverse aquatic vertebrates including fishes and amphibians. The increasing input of terrigenous sediments in the Upper Muschelkalk indicates the shift towards mixed terrestrial and marine facies during the Keuper. The Keuper represents the Late Germanic Triassic. With the increase of clastic influx, the marine connection between the Tethys and the Germanic Basin through the East Carpathian and the Silesian–Moravian gateways was interrupted (Ziegler, 1990). Lithostratigraphically, the Keuper is divided in Lower, Middle and Upper Keuper, which are subdivided in various formations with differentiations between basin central and marginal regions (Fig. 60). The lithologies differ between fluvial, lacustrine, shallow marine, lagoonal, evaporitic, deltaic, and sabkha facies. Important for lithostratigraphy is the so called “Schilfsandstein” (Stuttgart Formation, Middle Keuper; Late Triassic), which represent a basin wide marker (e.g., Kozur & Bachmann, 2010).

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Fig. 60. Lithostratigraphic subdivision of the Germanic Triassic in North, Central and South Germany (from Menning & DSK, 2002).

Fig. 61. Palaeogeographic map of the Germanic Basin during the Buntsandstein (Early Triassic). Thuringia (e.g., Caaschwitz section; Stop 5) is located at the southeastern margin of the basin (map modified from Röhling & Heunisch, 2010).

Stop 5: Caaschwitz quarry, continuous Permian to Triassic profile (Figs. 62, 63) Location: active quarry at Caaschwitz (Thuringia, Central Germany). Stratigraphy: transitional section of marine Zechstein (Late Permian) to terrestrial Lower Buntsandstein (Early Triassic). Coordinates: 50°57’09.12’’ N, 11°58’27.15’’ E.

Fig. 62. The active quarry at Caaschwitz (Thuringia, Central Germany). The section exposes the transition from the Late Permian marine Zechstein to the Early Triassic terrestrial Lower Buntsandstein. PTB marks the supposed positon of the Permian-Triassic boundary.

Outcrop: The large outcrop of recent surface mining as well as areas of underground mining and an abandoned quarry belong to the Wünschendorfer Dolomitwerke GmbH. The mined dolomite becomes used as flux agent in the metallurgic industry.

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Stratigraphy and facies: Currently, the active quarry at Caaschwitz provides one of the best exposed transitional sections of marine Zechstein (Late Permian) to terrestrial Lower Buntsandstein (Early Triassic) in western and central Europe. The 69 m of the exposed section can be subdivided in (from base to top): 

Plattendolomit (z3D member, Leine Formation): Bright gray, well bedded dolomite rock of a marine-evaporitic salinar deposit.



upper Zechstein (z3–z6): Gray and red clayto sandstones with dolomite nodules of a sabkha facies. Pedogenetic overprints of siliciclastics are classified as vertisols.



uppermost Zechstein (Fulda Formation, z7): Red, fine to coarse grained sandstones with horizontal bedding and small scale intercalations of channels at the base of the upper Fulda Formation (upper z7). Continuous shift to “Buntsandstein facies” showing clay- and sandstones with flaser/lenticular bedding, ripple marks and desiccation cracks. They are interpreted as playa lake deposits.



lower Calvörde Formation (basal Lower Buntsandstein; equivalents of oolite horizons α1, α2, β1): Horizontal and cross bedded, gray and red colored, fine to coarse grained siliciclastics with ripple marks, desiccation cracks and rip up clasts. A fluvial facies is indicated by small scale channels with internal trough-shape cross bedding. Single ooids or remnants of dissolved ooids occur frequently.

Fig. 63. Lithology and lithostratigraphy of the active quarry at Caaschwitz. The section exposes the transition from marine Zechstein (Late Permian) to terrestrial Lower Buntsandstein (Early Triassic).

Stratigraphy: Currently, the position of the terrestrial Permian-Triassic boundary (PTB) is under reinvestigation by Scholze, Schneider & research partners using conchostracan biostratigraphy, isotope chemostratigraphy, major-/trace-element geochemistry, magnetostratigraphy, and radiometric age determinations in order to correlate the international stratigraphic scale with the terrestrial PTB in the Germanic Basin. Additionally, palynofacies, sedimentary facies, and palaeosoil analysis are

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applied for reconstruction of environmental processes in respect to the end-Permian mass extinction. The lithostratigraphic Zechstein-Buntsandstein boundary at Caaschwitz was first defined by Schüler & Seidel (1991). However, this lithostratigraphic boundary is not equivalent with the terrestrial PTB. The position of the PTB is of controversial discussion. For example, Ecke (1986) used palynology for placement of the PTB between cycles 3 and 4 of the Calvörde Formation. More recent workers (e.g., Bachmann & Kozur, 2004; Kozur & Weems, 2010) defined the PTB at the base of cycle 2 in the Calvörde Formation by combining different stratigraphic methods (e.g., conchostracan biostratigraphy and isotope chemostratigraphy). According to the first results, the sediments of the lower Fulda Formation (lower z7) in the Caaschwitz section show a transition from decreasing vertisol overprint to an onset of internal flaser/lenticular bedding. The transition is interpreted as gradual shift from sabkha to playa lake facies. A sandstone bank of 4.20 m thickness marks the base of the upper Fulda Formation (upper z7). The sandstones mostly show horizontal to irregular wavy internal bedding, millimeter thick clay- to siltstone intercalations, centimeter small haloturbation, and irregular sand patches. These sandstones are interpreted as shallow subaquatic deposits, whereby occasional intercalated small scale channels indicate a fluvial to fluviolacustrine facies. The entire upper Fulda Formation shows a sedimentary character, which is generally more similar to the “Buntsandstein facies” (e.g., flaser/lenticular bedding) than the “Zechstein facies” (e.g., intensive vertisol overprint). The differences between these two facies suggest a climate change to more moist conditions starting in the Fulda Formation, which is predating the Zechstein-Buntsandstein boundary. The sandstones directly at the base of the upper Fulda Formation mark the most prominent climate change of the whole Zechstein interval in the Caaschwitz section. Fauna: So far, fossils are very rare in the siliciclastics of the upper Zechstein, because of generally hard living conditions in the sabkha environment of the upper Zechstein (z3 to lower z6). However, first poorly preserved tetrapod footprints within the upper Fulda Formation (upper z7) have been discovered by S. Voigt during recent field campaigns in the Caaschwitz section. New collected conchostracans determined as Palaeolimnadiopsis vilujensis (Fig. 64) and Euestheria gutta are known from the interval of the upper Fulda Formation to the cycle 3 of the Calvörde Formation (Lower Buntsandstein). The first data from the Zechstein in the Caaschwitz section indicate that fossil occurrences are restricted to well bedded deposits of the playa lake facies. The new data also suggest that statements on a Late Permian mass extinction should be handled with caution, because the fossil record generally depends on local facies differences as demonstrated by both the lack of fossils in the sabkha environment and the findings of conchostracans and tetrapods in the playa lake environment. Geochemistry: Currently, the Caaschwitz section is also studied for isotope (δ13Corg) analysis. New data obtained from the upper Fulda Formation indicate that changes of both the sedimentary facies and the fossil record are associated with a shift from heavier to lighter δ13Corg values. The first results suggest that changes of both sedimentary facies and δ13Corg signatures are governed by climatic changes. Such an assumption is very well supported by similar δ13Corg shifts at the base of the upper Fulda Formation also reported from drill cores in northern Germany (Hiete et al., 2013).

Fig. 64. Conchostracan determinded as Palaeolimnadiopsis vilujensis from the Calvörde Formation, Lower Buntsandstein (Early Triassic) in the Caaschwitz section.

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5. The Late Carboniferous – Permian Thuringian Forest Basin 5.1 Introduction The Thuringian Forest Basin (formerly SW-Saale basin), an approximately 40 to 60 km wide NW-SE orientated depression, is to large parts exposed in the horst structure of the Thuringian Forest (Fig. 65). It belongs to the classical Rotliegend areas in Europe because of the mining – since the 12th century – of Permian Zechstein Kupferschiefer deposits along the borders of this horst, sulfide ores in Rotliegend lacustrine black shales, Stephanian and Rotliegend coals, and Mesozoic vein deposits. F.G. Gläser published in 1775 one of the worldwide oldest hand-coloured geological maps that included parts of the Thuringian Forest. First geological descriptions and mapping activities date back to Voigt (1789) – a pupil of Abraham Gottlob Werner –, Freiesleben (1807), and von Hoff (1807), who developed here, before Lyell, ideas about the “principle of actualism”. The first description of Rotliegend plants where given by the coal mine owner Heyn in 1695, and the first Rotliegend plant was pictured by Mylius (a lawyer of the town of Leipzig) in 1709. The wealthy illustrated publication of von Schlotheim (1804) on floras of the “Rothliegend” and the “Steinkohlen-Formation” of the Thuringian Forest mark the start of scientific palaeobotany (cf. Barthel & Rößler, 1995; Barthel, 1994, 2003). Nowadays, this Rotliegend basin is one of the biostratigraphically best investigated and correlated basins in the Variscan area (Schneider, 1996, 2001; Lützner et al., 2007; Andreas et al., 2005; Schneider & Werneburg, 2006; Werneburg & Schneider, 2006, 2012).

Fig. 65. Simplified map of the Thuringian Forest with excursion stops (from Lützner et al., 2004). Inset map: zones of the Variscan foldbelt: MZ – Moldanubian zone, STZ – Saxothuringian zone, RHZ – Rhenoherzynian zone; small square near h indicate position of the Thuringian Forest Mountains.

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Fig. 66. Stratigraphy, lithology and fossil content of the Late Carboniferous and Permian Thuringian Forest basin after Schneider (1996, 2001), Werneburg & Schneider (2006), Voigt (2005), Barthel (2008); lithostratigraphy after Lützner et al. (2007) and Andreas (1996), chronostratigraphy after Schneider & Werneburg (2006, 2012), and Lützner et al. (2007). The numbers in the circles indicate the most important fossiliferous horizons: 1 – Öhrenkammer Member and Ilmtal Member; 2 – plants in pyroclastics; 3 – Möhrenbach lake; 4 – Lindenberg tuff; 5 – Sembachtal lake; 6 – coal seams and Manebach or Kammerberg lake respectively; 7 – Acanthodes lake horizons; 8 – lower Protriton lake; 9 – middle Protriton lake; 10 – Spittergrund track horizon; 11 – upper Protriton lake; 12 – Hefteberg and Gasberg track horizons; 13 – Bromacker tetrapod horizon; 14 – Lower Claystone or Claystone 1.

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5.2 Basin development and basin fill (Fig. 43, 66) The basin is situated on deeply eroded and peneplained Variscan basement of the Saxothuringian Zone in the southeast, Visean granites in the center, and the inverted Mid-German Crystalline Zone (MGCZ) as well as the Rhenoherzynian zone in the northwest (Fig. 43). Basin development, sedimentation and volcanism were controlled by NE-SW, NW-SE, N-S, and E-W striking fault systems, which cause a changing pattern of subsiding and uplifting blocks during sedimentation. In consequence, small sub-basins with partially strong relief gradients were created (see Andreas, 1988, 2014; Lützner, 1988; Lützner et al., 2007, 2012). Sedimentation starts on deeply weathered Variscan granites with red (basin margin) and grey (basin center) conglomerates and coarse arkosic sandstones that are overlain by fluvial to lacustrine and palustrine fine-clastic deposits with fossiliferous lake horizons and thin coal seams with hygrophilous floras of the Gehren Subgroup (Möhrenbach and Georgenthal Formations). Typical lake sediments are black shales and thin, partially onkolitic limestones. Xenacanthid freshwater sharks and branchiosaurid amphibians of the Ilmtal lake horizon close to the base of the Gehren Subgroup give a Stephanian C age (Werneburg & Schneider, 2006; Schneider & Werneburg 2012). The freshwater sharks of this lake horizon indicate the connection to a Europe-wide drainage system (Schneider & Zajic, 1994; Schneider et al., 2000). The sedimentary sequence is overlain by up to 1,000 m of intermediate to acidic pyroclastics and lavas, in places subintrusive, with intercalated fluvial to lacustrine red and grey sediments and thin lacustrine limestones. Sparse floral remains belong to meso- to xerophilous plants. After the development of a basin-wide erosional disconformity, the maximally 450 m thick Ilmenau Formation, which is characterized by bimodal volcanism (rhyolites and basalts), was deposited. The base of this formation marks the base of the Rotliegend. The formation contains several sedimentary members, mainly in grey facies, which are dominated by local volcaniclastic components. The Sembachtal-lake horizon close to the top of the Ilmenau Formation consists of fluvial grey sediments and lacustrine laminated black shales with stromatolitic layers. Based on amphibians, this horizon belongs together with the following Manebach Formation to the Apateon dracyiensis - Melanerpeton sembachense Zone, which is of Late Gzhelian to Early Asselian age (Werneburg & Schneider, 2006; Schneider & Werneburg, 2012; Schneider et al., 2013). The overlying coal-bearing, maximally 180 m thick, completely grey Manebach Formation was deposited in a low-relief landscape with forest swamps, local lakes, and fluvial mud deposits rich in organic matter (Lützner, 2001). Volcanic rocks in the Manebach Formation are restricted to millimeter to centimeter thick ash layers within the lacustrine black shales. This formation is famous for its characteristic and well investigated Euramerian Stephanian/Lower Rotliegend flora (e.g., Barthel, 2001, 2003–2008). During the deposition of the up to 800 m thick Goldlauter Formation, a marked palaeorelief developed, which is reflected in red-brown coarse-clastic alluvial fan deposits along the margins of the basin. The fans interfinger distally with red alluvial plain sandstones and siltstones, fluvio-lacustrine brownish to grey sandstones, and lacustrine laminated black shales in the centre of the basin. Some of the lake horizons could be traced at the scale of the entire basin by pyroclastic marker beds (Andreas & Haubold, 1975). These mostly black shales were deposited in interchanging acanthodian/xenacanthid and palaeoniscid/amphibian dominated lakes. Very common blattid insects and branchiosaurid amphibians allowed for detailed correlations within the entire Euramerian palaeotropical belt (Schneider & Werneburg, 2006, 2012; Werneburg & Schneider, 2006; Schneider et al., 2013). At the base of the Oberhof Formation, the widespread 5 to 50 m thick Dörmbach pyroclastic horizon initiates the second major phase of volcanism, which led to up to 1,200 m rhyolitic lavas, in places subintrusive, and pyroclastic rocks, with minor intercalations of epiclastic sediments that form the Oberhof Volcanite Complex (Lützner et al., 2007). Laterally, this complex merges into alluvial and lacustrine sediments with minor intercalations of lavas and pyroclastic rocks. Epiclastic sediments amount to only 10% of the formation. Red bed facies is more widespread than in the preceding Goldlauter Formation. In the upper Oberhof Formation, the last perennial lake horizon of the Thuringian Basin is very widespread and grades laterally from calcareous, bituminous, varved black shales into red, varved, carbonate-clay laminites (Schneider & Gebhardt, 1993). These sediments are covered by alluvial plain and playa-like deposits at the top of the Oberhof Formation. The fauna of the Oberhof lake horizons is dominated by amphibians. Fishes are rare and of low diversity. Based on the amphibians, this formation is very well correlatable with the latest Lower Rotliegend (Sakmarian) of most basins in Europe (Werneburg & Schneider, 2006). After an erosional event, which cut down as far as into the Lower Oberhof Formation, the deposition of the Rotterode Formation started with entirely red clastics. This sequence of sandstones with intercalated channel and sheet flood conglomerates as well as siltstones was deposited in an alluvial fan – alluvial plain environment. The appearance of granite pebbles and arkoses of granite detritus 82

indicate the first uplift of the Ruhla Crystalline Complex at the western border of the basin. Locally, rhyolitic lavas and pyroclastics occur. The emplacement of the S-N directed, up to 250 m wide Höhenberg dolerite was a major event dated at 280  2 Ma (Artinskian, see Lützner et al., 2007). Scoyenia burrows and plant roots in sandy alluvial plain siltstones are typical of the “wet red bed facies”. Siltstones and claystones of temporary pools and small playa-like ponds contain the freshwater jellyfish Medusina limnica as well as common arthropod and tetrapod tracks. Biostratigraphically the Rotterode Formation belongs to the Moravamylacris kokulovae insect zone, which indicates an Upper Rotliegend I (Sakmarian/Artinskian) age (Schneider & Werneburg, 2006). With a shift of the depocentres to the north, again after a hiatus, the up to 250 m thick Tambach Formation was deposited on a volcanic relief dissected in part by canyons (Lützner & Mädler, 1994; Lützner et al., 2007). Facies patterns range from very coarse, matrix supported wadi-fill conglomerates to proximal and distal debris-flow dominated alluvial fan clastics as well as floodplain sandstones and floodbasin siltstones. The sandstones are interpreted as fluvial reworked aeolian sandstones, primarily accumulated in the hinterland (Schneider & Gebhardt, 1993). Scoyenia-facies, indicative for wet red beds, is typical of these alluvial plain deposits (Martens et al., 1981). The flora consists of xerophilous walchians and cones of the drought-adapted Calamites gigas. Tambach is famous for complete, articulated vertebrate skeletons, preserved in mud flows (Martens, 1988; Berman & Martens 1993; Eberth et al., 2000). The fauna includes reptiles and terrestrially adapted amphibians, which at the genus level are close to North American Early Permian tetrapod faunas. Based on tetrapods and insects (Moravamylacris kukalovae), the Tambach Formation is correlated with the North American late Wolfcampian/early Leonardian, i.e. the Sakmarian/earliest Kungurian (Schneider & Werneburg, 2006; Lucas, 2006). The 400 m to 600 m thick completely red Eisenach Formation occurs only at the western flank of the Ruhla Crystalline Complex and the adjacent Werra basin (Lützner, 1981, 1994). The marginal facies is represented by the interfingering of monotonous fanglomeratic alluvial fan deposits and red silty to sandy mudstones. They were deposited on an apron of alluvial fans with predominantly sheet-flood deposits that interfinger towards the basin centre with fine clastics of playa mudflats. Evaporitic conditions are indicated by common haloturbation and mm-sized gypsum crystal casts in playa siltstones. Well-rounded, coarse sand grains (2–3 mm) in the alluvial fan fine-clastics are indicative for reworked aeolian deposits. The fossil content consists of the playa-jellyfish Medusina limnica; ephemeral pond deposits contain conchostracans and leaves of Taeniopteris sp. (Voigt & Rößler, 2004). In places arthropod and tetrapod tracks are not rare. The Förtha (Schneider, 1996) or Neuenhof Formation (Lützner et al., 2012) comprises the youngest Rotliegend sediments below the marine Zechstein. The up to 20 m thick sandy and conglomeratic sediments are partly fluvial deposits; poorly sorted, indistinctly horizontally stratified, matrix-supported fanglomerates are interpreted as debris flows. Their primary red colour changed to grey some meters below the marine Zechstein conglomerate, even granite pebbles are completely leached to pale grey. Horizontal nodule layers are regarded as groundwater calcretes. These calcretes and the leaching are interpreted as effects of the marine pre-Zechstein-ingressions into the Southern Permian Basin and the Zechstein-transgression, which caused a maritime influence on the arid continental climate (Schneider, 1996, 2001). Above this formation, marine reworked coarse clastics and the Kupferschiefer form the base of the Zechstein. The Kupferschiefer is dated by the conodont Mesogondolella britannica as Wuchiapingian (Legler et al., 2005), which fits well with the 187Re-187Os isochron age of 257.3 ± 1.6 Ma (Brauns et al., 2003).

Stop 6: Manebach, Late Carboniferous/Early Permian coal bearing grey facies, classical palaeobotanical outcrop since Mylius 1709 and Schlotheim 1804 (Figs. 67–70) Stratigraphy: Manebach Formation, Lower Rotliegend, Gzhelian/Asselian transition. Location: southern entrance of Manebach near Ilmenau, Kammerberg at the road B4. Coordinates: N 50° 40.378´; E 10° 51.566´. Thickness: 20 m to 180 m. Base: basal conglomerate overlying the Gehren Subgroup. Top: basal conglomerate ("Melaphyrmandelstein-Konglomerat") of the following Goldlauter Fm.. Biostratigraphy: Sysciophlebia ilfeldensis- to S. balteata-zone (Schneider & Werneburg 2012) giving an Gzhelian/Asselian transitional age based on co-occurrences of insect zone species with conodonts at Carizzo Arroyo, New Mexico, after Schneider in Lucas et al. (2013); Apateon dracyiensis – Melanerpeton sembachense-amphibian zone (Werneburg & Schneider, 2006; Schneider &

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Werneburg, 2012); xenacanth shark teeth: Bohemiacanthus Um- to Om-zone (Schneider, 1985; Schneider & Zajic, 1994). Magnetostratigraphy: Possibly the (questionable) Normal Subzone within the lower Manebach Formation (Menning et al., 1988) corresponds to the Normal Subzone at the Ghzelian/Asselian boundary (base of the Sphaeroschwagerina aktjubensis – S. fusiformis fusulinid zone; Davydov et al, 2010).

Fig. 67. Sedimentology and fossil content of the Manebach Formation (Early Permian) at the type locality south of Manebach village, slope at the B4 road, Thuringian Mountains, Germany; excavation site 2005, comp. Fig. 69 A. Channel lag deposits at profile-meter 5 contain calamite trunks as well as the Onchiodon remains – skull of about 30 cm length with the lower jaw as well as femur (Fem) and ilium (Il). (From Gebhardt et al., 1995; completed after the 2005 excavation by Werneburg).

Lithology, facies and fossil content: The coal-bearing, up to the basin borders completely grey Manebach Formation was deposited in a low-relief landscape with forested mires, local lakes, and fine-clastic-dominated fluvial deposits rich in organic matter. Volcanic rocks in the Manebach Formation are restricted to mm to cm thick ash layers within lacustrine black shales. This formation is famous for its characteristic and well investigated Euramerian Stephanian/Lower Rotliegend (Gzhelian/Asselian) flora (e.g., Barthel, 2001, 2003–2008). Based on both the lithofacies and fossil content the following sub-environments could be distinguished in the Manebach Formation (Fig. 67, Fig, 69 A; for details see Barthel 2001, 2003–2008; Schneider, 1996; Werneburg, 1997; Lützner, 2001): 1. Medium- to coarse-grained, pebbly, trough cross-bedded channel sandstones; common are stem and strobili remains of Calamites gigas, twigs of meso- to xerophilous conifers (“walchians“) and skeletal remains of the eryopid amphibian Onchiodon (Fig. 69 B) as well as isolated bones of a pelycosaur (?Haptodus) (Werneburg, 2007). In the immediate neighbourhood of channels as well as in point bar sandstones and channel sandstones itself, C. gigas has been found buried in an upright position (Fig. 69 E). At the Manebach localities, this unique succulent calamite forms (nearly) monotypic stands with about 1 m distance between the stems (Barthel & Rößler, 1996; Barthel, 2001). 2. Fine- to coarse-grained sheet sands generated during flood events as overbank deposits and crevasse splay deposits; autochthonous C. gigas stands are as above as well as allochthonous remains of meso- to xerophilous plants from different growth sites above the groundwater level, such as sand bars along river courses and from drier, elevated areas inside the basin and along the basin borders (callipterids, different conifers such as walchians, the coniferophyte Dicranophyllum and Odontopteris lingulata, etc.). 3. Fine, sandy siltstones to clayey floodplain siltstones deposited during waning stages of flood events with layers of species-rich parautochthonous (often well preserved large fern fronds)

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hygro- to mesophilous plant remains, representative of the fern-pteridosperm-calamite vegetation of floodplain areas outside the peat-forming mires; Arthropleura remains are not rare. 4. Laminated claystones and siltstones of floodplain pools between the channels, with layers of Anthraconaia (Fig. 69 D) in places homogenized by bioturbation (Pelecypodichnus). 5. Rooted siltstones and claystones of very wet floodplains, in places pure hydromorphic to subhydric cordaitalean root horizons of coal-forming forest mires; in the roof shales of seams the autochthonous swamp forest communities are preserved; most common are Psaronius ferns with their fronds (Pecopteris, Scolecopteris) and pteridosperms, like Odontopteris schlotheimii, Dicksonites pluckenetii, Taeniopteris jejunata, different neuropterids and others, the hygrophilous Calamites multiramis and C. undulates as well as the coal-forming cordaitaleans (Barthel, 2001); insect remains are present (mostly cockroaches). 6. Above the coal-seam-containing part of the profile there appear lacustrine, carbon-rich siltstones and claystones with the typical Early Permian palaeoniscid-xenacanthid-fish association of smaller lakes (Schneider et al., 2000). Branchiosaur amphibians are very rare; common lacustrine invertebrates are ostracods, and, in layers, conchostracans; terrestrial biota are represented by diverse plant fragments and blattid insects (most common, as in many Euramerian lake sediments, is Anthracoblattina). The Manebach locality has been sampled by private plant collectors and palaeobotanists for about 300(!) years (Barthel & Rößler, 1995). Collecting has focused on the plant-rich roof shales of the coal seams. Arthropleura and tetrapod skeletal remains were never discovered before the first palaeontological research in the fluvial deposits of this profile commenced (Werneburg, 1987, see 1989; Schneider & Werneburg, 1998). Obviously, they are restricted to those fluvial deposits and their depositional environments. From reconstructed leg length and the size of paratergits (“pleurites”) a body lengths of 0.85 m to 2.25 m has been calculated for the individuals from Manebach (Fig. 68, 70). Palaeoclimate: The Manebach Formation belongs to the Late Gzhelian/Early Asselian wet phase C of Roscher and Schneider (2006), which is represented, e.g., in the Saar-Nahe basin of western Germany by the Breitenbach to Altenglan Formations and in the French Massif Central by the Molloy and Igornay Formations (Roscher & Schneider, 2006: Fig. 15 a–b). Red sediment colours are nearly completely missing; only in the alluvial fan conglomerates of the basin border facies do violet-coloured coarse clastics appear in places. Characteristically, coarse channel clastics are of whitish-yellowish colour, which is interpreted as a result of leaching by paleo-groundwater flows. This is supported by the presence of pale grey leached, primary dark violet to reddish brown rhyolite clasts of the fan and channel conglomerates (Lützner, 2001; Lützner et al., 2007). Lamination as an indication of seasonality is not really well expressed in the lake deposits. Therefore, nearly year-around high precipitation as well as high groundwater levels can be inferred. In this way, the Manebach Formation is climatically very close to the Westphalian C (Bolsovian) and early Westphalian D, from which most Arthropleura remains were discovered in Europe. Both Arthropleura and Onchiodon lived outside the swamp areas in a river landscape that was dominated by Calamites gigas stands along the river banks as well as by fern-pteridosperm-calamite vegetation on floodplain areas between river courses. Outcrop situation: coal-bearing part of the Upper Manebach Formation, typical Lower Rotliegend grey facies. Facies associations: fluvial and palustrine, locally lacustrine grey beds containing several coal seams, channel/interchannel deposits, wooded floodplain/flood basin, swamps, dominantly hydromorphic gleysols/histosols with cordaitalen roots of a poorly drained alluvial plain, thin pyroclastic horizons, dominantly hygrophilous plant communities (type locality of very common Rotliegend species, described by Schlotheim, Sternberg, Mahr, Weiss, Potoniè, Gothan, Remy, Barthel; for details see Barthel & Rößler, 1995).

Fig. 68. Arthropleura remains from Manebach. Collum fragment (C), 6.3 x 2.9 cm; as discussed by Schneider & Werneburg (1998), the dorsal elements of the exoskeleton appear weaker scupltured as known from older remains; if this is an taphonomic effect only, remain open so far. The plant remains belong to Annularia spinulosa (A), Calamostachys tubercolata (Ct) and pecopterids (P); Kammerberg excavation bed 22b; NHMS-WP 3379.

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Fig. 69. Exposure and fossil content of the Manebach Formation (Early Permian) at the type locality south of Manebach village, slope at the B4 road, Thuringian Mountains, Germany. A, Excavation site 2005, numbers 2 to 8 refer to the meter-scale in Fig. 67; remains of the eryopid Onchiodon thuringiensis Werneburg 2007 were found in the pebbly channel sandstones at 5, Arthropleura remains comes from plant-containing overbank siltstones between 7 and 8 as well as from loose blocks. B, ca. 30 cm long skull of Onchiodon thuringiensis; NHMS-WP 2140a. C, Cardiocarpus fructifications washed together in fluvial fine sandstone; NHMS-WP 3310. D, Freshwater pelycipod Anthraconaia in floodplain pool siltstones; NHMS-WP 3350. E, runk base of Calamites gigas buried upright in fluvial sandstone; NHMS-WP 3407.

Fig. 70. Habitat of Arthropleura in an alluvial plain environment with Calamites gigas vegetation; reconstruction based on the facies patterns in the Manebach Kammerberg outcrop as well as on the Arthropleura track occurrences in Nova Scotia and New Mexico (Schneider et al., 2010). Reconstruction of the xerophytic Calamites gigas based on Barthel & Rößler (1996). The insect is a cockroach-like spiloblattinid; the eryopid amphib Onchiodon after Werneburg (2007); the tetrapod track on the right symbolize the occurrence of reptiles in the Arthropleura habitat as indicated by skeletons (Schneider et al., 2010).

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Stop 7: Schleusingen - Museum of Natural History in the Bertholdsburg Castle Location: lovely small town Schleusingen, southern Thuringia, Museum of Natural History in castle Bertholdsburg. Coordinates: N 50° 30.547´; E 10° 45.996´. History: the castle was built between 1226 and 1232; since the end of the 13th century it was the residence of the counts of Henneberg and it is in this way the oldest residence castle of Thuringia. Up to 1530 completed to a four winged complex with 9 towers and a castle well. This situation has been preserved over 500 years to nova days. Museum of Natural History: In 1934 a very small local museum of geology and palaeontology, the so called "Franke-Zimmer" (Franke cabinet), was founded as a forerunner. It was since 1953 a museum of homeland history and since 1984 as Museum of Natural History responsible for the area of Southern Thuringia. All important local geological and biological collections from several towns (e.g., Meiningen, Schmalkalden, Eisfeld, Hildburghausen, Sonneberg, etc.) of Southern Thuringia (from a time when education was more important than football in Germany) are since 1988 concentrated here and well conserved and curated for future times. The museum act as a well-known superregional centre for education in natural sciences, edit an own journal for natural sciences, the “Semana Veröffentlichungen Naturhistorisches Museum Schleusingen“ and is very active in organising any cultural events from Medieval Festivals to Irish Folk days. Besides a marvellous exhibition of “Minerals – fascination of Form and Colour” as well as an exhibition on the long mining history in the Thuringian Mts. area, the main exhibition focus on the history of live. This main exhibition is devoted to the “Footsteps of our living habitats – 300 million years Thuringia”. Demonstrated are interactions between organisms and environments with exceptional fossils and very impressive dioramas of the ancient, hundreds of million years old nature (project of the German Federal Environmental Foundation). Key aspects are  the lakes, river landscapes and swamps of the Permian Rotliegend (Figs. 71, 72)  the shallow seas, reefs and coasts of the Zechstein sea  the river landscapes of the Early Triassic Buntsandstein  the shallow sea of the Triassic Lower and Upper Pelecypod Limestone (Muschelkalk)  the interchange of landscapes with rivers, lakes and swamps with shallow marine floodings during the Late Triassic early Keuper  river landscapes of the Middle Keuper  maar and sinkhole lakes of the Tertiary  change of different landscapes during warm and cold climate phases of the Pleistocene in Thuringia. A ”time gate“ leads into the modern landscape of Thuringia. After the visit of the museum we will have a barbeque in the courtyard of the castle with the director of the museum “burgrave Ralf of Werneburg”.

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Fig. 71. Diorama of Early Permian coal forming forest with tree ferns (Psaronius trunk and Pecopteris leaves); Manebach Fm.; Museum Schleusingen.

Fig. 72. Diorama of an Early Permian amphibian dominated lake with Sclerocephalus (~ 1m long), small branchiosaurid amphibians and palaeoniscoid fishes; Museum Schleusingen.

Stop 8: Oberhof, typical late Lower Rotliegend, Sakmarian/Artinskian, lake horizon in the level of last perennial lakes in Central Europe Stratigraphy: Lower Oberhof Formation, late Lower Rotliegend, Sakmarian/Artinskian transition Location: Lochbrunnen near Oberhof, Alte Ohrdrufer Street. Coordinates: N 50° 42.439'; E 10° 42.998'. Thickness: 400 m to 1.200 m depending on the thickness of intercalated volcanites. Base: up to 50 m thick Dörmbach tuff horizon. Top: erosive base of the Rotterode or Tambach Formations. Biostratigraphy: conchostracans: Lioestheria pseudotenella-zone (MARTENS 1987); aquatic tetrapods: L. Oberhof Fm. – Apateon flagrifer oberhofensis – Melanerpeton arnhardti-zone (Werneburg & Schneider, 2012), U. Oberhof Fm. – Melanerpeton pusillum – Melanerpeton gracilezone (Werneburg & Schneider, 2012); insects: perhaps Sysciophlebia alligans- to Spiloblattina odernheimensis-zone (Schneider & Werneburg, 2006, 2012). Isotopic age: 287 ± 2 Ma (Ar/Ar), Goll & Lippolt (2001) – biostratigraphically a 290 Ma age is realistic. Lithology/facies (Fig. 73): Intense volcanism and volcano-tectonics during deposition of the formation caused fast lateral changes of facies patterns. Generally, the up to 1.200 m thick formation exhibits a four time change of 100 m to 200 m pyroclastics and 100 m to 350 m of sandy to pelitic red beds (Lützner et al., 2012). Intercalated are levels of fluvio-lacustrine grey sediments with lacustrine laminated black shales. In the area of the Oberhof Volcanite Complex about 90% of the profile consists of volcanites only.

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A

Fig. 73. Type profile and basin configuration of the Oberhof Fm. A – Type profile of the basin centre west of the Oberhof Volcanite Complex (OVC); indicated are lake levels in the sediment sequences: 8 – Lochbrunnen lake horizon, between 8 and 9 – Nesselhof lake horizon, 9 – Spittergrund lake horizon (SpS), 10 – Wintersbrunnen lake horizon; B – basin configuration with a N-S basin axes, dashed line with crosses – western border of the OVC. (Modified from Lützner et al., 2012).

B

Sediments consist mainly of conglomeratic fan deposits, sandy to silty alluvial plain and silty to clayish lake sediments. Wet red bed facies dominate; only in the lower sedimentary unit appear in places grayishviolett colours. In the uppermost unit a change from wet to dry playa like deposits is observable. Grey facies is otherwise restricted to the four lake levels. Lake sediments are characterised by dense clay/silt lamination (writes), rich in organic carbon and mostly calcareous. The lakes have been shallow and oxygen depleted. Palecological they represent the type of amphibian lakes. Dominating are small branchiosaurs as Melanerpeton gracile and Apateon flagrifer oberhofensis, top predators as Sclerocephalus, Onchiodon, and Discosauriscus are rare (Werneburg, 1989 ff.; overview in Werneburg & Schneider, 2006). The fish fauna is generally impoverished – only Xenacanthus appear in all four lake levels; actinopterygians as Paramblypterus and one ?aeduellid appear in the last lake level, the Wintersbrunnen lake, only. Mesophilous and xerophilous plants as Odontopteris, calipterids and the by fare dominating conifers represent the flora of lake borders and the hinterland. Red fluvial and shallow-lacustrine siltstones are in places very rich in arthropod and tetrapod traces, especially in the upper three sediment units (Walter, 1982, 1983; Voigt, 2005). Fossil content (Fig.75, B,C,D):  mesophilous to xerophilous flora with diverse conifers, several callipterids and Odontopteris lingulata; last occurrence of the lycopsid Sigillaria brardii in the Thuringian forest basin;  aquatic invertebrates, as bivalves, ostracods, conchostracans, triopsids and the syncarid shrimp Uronectes  insects mainly phyloblattids and xeromorphic mylacrids  arachnids and diplopods  Paramblypterus,?aeduellid, Xenacanthus;  diverse amphibians as Melanerpeton gracile thuringense, Apateon flagrifer oberhofensis, ?Onchiodon labyrinthicus, Sclerocephalus jogischneideri, Discosauriscus pulcherrimus and ?Cardiocephalus sp.;  diverse arthropod and tetrapod tracks. Palaeoclimate: Strong seasonality is proven by the laminated lake sediments as well as by repeated mass occurrences of adult conchostracans and triopsids on distinct bedding planes, representing ontogenetic cycles. The lakes of the Oberhof Formation belong to the Late Sakmarian/Early Artinskian wet phase D of Roscher & Schneider (2006), which correlates biostratigraphically with the Niederhäslich lake horizon of the Döhlen basin, the Reinsdorf lake horizon of the Chemnitz basin, the Olivětín lake horizon of the Intra Sudetic basin, Svitavka lake horizon of the Boskovice graben, the lakes of the Disibodenberg Formation in the Saar-Nahe basin and the Buxiers and Millery lake horizons of basins in the French Massif Central, etc.. This phase is again dryer than the foregoing one as indicated by

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widespread red beds, dominating meso- to xerophilous elements in the flora and the mostly impoverished fish fauna. Outcrop situation: The new outcrop was prepared during a 2-weeks excavation field course 2012 of students from Freiberg together with the team of the Museum Schleusingen and well supported by local administrations. The investigation in the frame of an MSc thesis is still in progress.

Exposed is the transition from tetrapod tracks (Dromopus lacertoides, Amphisauropus) bearing red fluvial overbank sediments (Fig. 74, A) into transitional fluvio-lacustrine grey facies in the lower part of the outcrop (B), and lacustrine black shales with intercalated mudstones and sandy siltstones of the Lochbrunnen lake horizon (C), and in the top into fluvial sandstones (D).

Fig. 74. Lochbrunnen lake horizon near Oberhof, Lower Oberhof Formation, late Lower Rotliegend, Sakmarian/Artinskian transition; A – red fluvial overbank sediments, B – fluvio-lacustrine gray facies, C – lacustrine black shales, D – fluvial sandstones.

B

C

D

A

Fig. 75. Lochbrunnen lake horizon near Oberhof, see Fig. 74; A – profile C, transition from the litoral into the pelagial facies and repeated changes between both; scale 1 m; B – fluvial red beds with Amphisauropus tracks from fluvial red beds, profile A; C – plant debris from the litoral section B, mainly walchian conifers; D – the syncarid shrimp Uronectes from pelagial sediments in C.

Stop 9: Friedrichroda; Lower Rotliegend, Sakmarian, lake and alluvial fan deposits Stratigraphy: Goldlauter Formation, Lower Rotliegend, Sakmarian, Early Permian. Location: Friedrichroda, abandoned Gottlob quarry, Schmalkaldener street, B 88 road. Coordinates: N 50° 51.017'; E 10° 33.621'. Thickness: maximally 840 m (well Zella Mehlis).

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Base: basal conglomerate of the Goldlauter Fm., consisting mainly of volcanite pebbles, some show a weathered, orange coloured outer surface crust. Top: Dörmbach-tuff horizon at the base of the Oberhof Formation. Biostratigraphy: Sysciopplebia balteate form H – Spiloblattina homigtalensis and Sysciopplebia balteate form H – Spiloblattina sperbersbachensis insect zone (Fig. 46; Schneider & Werneburg, 2006, 2012); Apateon dracyiensis to Melanerpeton eisfeldi amphibian zone (Werneburg & Schneider 2006; Schneider & Werneburg, 2012); xenacanth teeth Bohemiacanthus Ogo-zone (Schneider, 1985; Schneider & Zajic 1994); conchostracans: Pseudestheria angulata – to Ps. glasbachensis-zone (Martens, 1987). Isotopic age: a very imprecise 288 ± 7 Ma (U/Pb) age for the pyroclastite No. 1 only (Lützner et al., 2007).

Fig. 76. Profile of the abandoned Gottlob quarry, Friedrichroda. From 0 to 1.0 m – fluvial fine clastics; 1.0 m to 2.6 m – transitional fluvial to littoral deposits; 2.6 m to 3.0 m – subaquatic deposited tuff No. 2; 3.0 m to 4.5 m – interbedding of littoral deposits and pelagial laminites; 4.5 m to 6.1 m – mainly pelagic laminites; 6.1 m to 6.8 m – very coarse conglomeratic distal debris flow horizon. From there up to the top of the quarry progradating conglomeratic fan deposits. A – specimen with a trash line of Medusina atava as well as Ichniotherium cottae and Dromopus lacertoides tetrapod tracks; B – lecto- and syntypes of M. atava, diameter up to 10 cm, scale bar 5 mm; from Schneider in Gand et al. (1996). C and D – ecomorphotypes of the branchiosaur Apateon dracyiensis from the Lower Goldlauter Fm. (Werneburg, 2002); C – the quite water pond type with long external gills and a wide tail fin; D – the flowing water stream type with short external gills and a narrow tail fin.

Lithology/facies (Fig. 76): After the Manebach Formation new accumulation space was generated by tectonical relief rejuvenation which created a NW-SE extended basin with steeper facies gradients at the NE basin border which was flanked by the pronounced Plaue-Ohrdruf swell (Lützner et al., 2012). Sedimentation starts after an erosional hiatus with coarse conglomerates which contain besides fresh debris remnants of older, now eroded screes from Manebach times (volcanite pebbles with orange coloured outer surface crust). The often very coarse debris flow dominated up to 100 m thick alluvial fan deposits form a front of fans especially along the swell at the NE basin border. Brownish to brownish-red colours are typical for the alluvial plain to flood plain deposits as well. Purple to grey clastics appear together with

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lacustrine black shale deposits mainly in the basin centre only. Several pyroclastic horizons (tuff No 0, 1 and 2; Andreas & Haulbold, 1975; Andreas, 2014) preserved in lake deposits are useful marker beds for the lithostratigraphy; unfortunately the isotopic ages show a strong overprint by a Mesozoic thermal event (Lützner et al., 2007). Fossil content (Fig. 76):  aquatic invertebrates, as bivalves, ostracods, conchostracans, triopsids, the syncarid shrimp Uronectes and the freshwater jellyfish Medusina atava;  insects mainly phyloblattids, spiloblattinids, xeromorphic mylacrids, and grylloblattids; the aquatic wingless monuran insect Dasyleptus  arachnids and diplopods  actinopterygians as Paramblypterus, Elonichthys, Westollia; common acanthodians, freshwater sharks as Xenacanthus and Bohemiacanthus  diverse amphibians as Apateon flagrifer flagrifer, A. dracyiensis, Schoenfelderpeton prescheri  and Branchierpeton reinholdi in the Lower Goldlauter Formation and Melanerpetoneisfeldi, A. flagrifer flagrifer, A. kontheri and the eryopide Onchiodon labyrinthicus in the Upper Goldlauter Formation  one araeoscelide reptile  a diverse tetrapod track fauna is known from more than 60 localities with the ichno-genera Batrachichnus, Limnopus, Amphisauropus, Ichniotherium, Dimetropus, Dromopus and Tambachichnium (Haubold, 1985; Voigt, 2005).  the flora is dominated by meso- to xerophilous elements, most common are more than 10 conifer taxa and seed ferns as Sphenopteris germanica, Autunia conferta, Arnhardtia scheibei, A. mouretii, Odontopteris lingulata; the xerophytic Calamites gigas (with Metacalamostachys dumasii); the ginkgophyte Sphenobaiera digitata; new and not rare are cycadophytes as Pterophylllum cotteanum. Palaeoclimate: Typical for the Goldlauter Formation and time-equivalent deposits of the middle Glan Subgroup of the Saar-Nahe basin as well as the Härtensdorf and Planitz Formations of the Chemnitz basin are lateral and vertical changes between the dominating wet red bed facies and basin central grey deposits (Schneider et al., 2006; Roscher & Schneider, 2006; Schindler, 2007). Lakes are relatively common but mainly of the shallow, instable amphibian-lake type. Only some of them are longer living and basin-wide extended, as the so called Acanthodes-lake horizons in the Goldlauter Formation. The well expressed lamination of carbon-rich black pelagic lake sediments indicate strong seasonality. This is confirmed by the now widespread triopsids, which are well adapted to seasonal dryness. Besides Medusina atava appear Medusina limnica, which became later (starting in the Artinskian/Kungurian) the typical facies fossil for dry red beds of the playa facies. Fluctuating groundwater levels are indicated by the Scoyenia facies and immature calcic soils of alluvial plain and flood plain sediments. Increased aridisation compared to the foregoing Manebach Formation is justified by the now callipterid- and/or conifer-dominated floral associations. Facies associations: proximal debris flow-dominated alluvial fan facies, braided pattern-fluvial channels, delta progradation into lacustrine environments, lacustrine sequences showing wide variety of subenvironments (suspension load into silent water areas, rhythmic horizons, possibly depending on seasonal climatic influence), rich faunal and floral remains indicating stable lacustrine environments with response of mesophile to xerophile upland plant communities. Outcrop situation: The exploitation of building stones from the end of the 19th century up to middle of the 20th century has delivered thousands of fish and amphibian fossils, collected by private collectors and distributed in museums all over Europe and North America. B. von Cotta, the professor from Freiberg, has discovered here in 1848 the first tetrapod tracks from the Permian of the Thuringian Mountains (Voigt, 2005). The outcrop shows the Upper Acanthodes lake horizon of about 4 m thickness with the intercalated tuff No. 2 (Andreas & Haubold, 1975). The lake sedimentation is abruptly finished by the shedding of debris flow conglomerates from the adjacent Plaue-Ohrdruf swell into the lake basin. Interestingly load casts have depths of centimetres only, obviously the flow was sliding on the lake deposits as indicated by decimetre to metre-long horizontal slump folds in the laminites below. Sandy-silty transitional fluvial to littoral deposits contain plant debris as well as trash lines of Medusina atava and tetrapod tracks (Dromopus, Ichniotherium). Remains of mesophilous seed ferns (Arnhardtia scheibei, Odontopteris lingulata) and of the dominating xerophilous conifers point on dry well drained habitats in the surroundings and the hinterland of the lake.

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Fig. 77. Mass-death layer with calculated 1,500 skeletons of branchiosaurs; Lower Goldlauter Fm., Cabarz quarry (Werneburg, 2008).

The aquatic fauna of the laminites of the pelagial changed depending on water depth and oxygenation from deeper fish lake associations to shallow lake amphibian dominated associations. The predatory Elonichthys is represented by about 90% beyond several thousands of fish finds, it follow Westollia, a plankton and plant feeding fish, by only 10% (personal comm. T. Schindler, 1996), Acanthodes and xenacanthids are rare. Of about 5.000 branchiosaur specimens from here about 90% are represented by the small plankton feeding Apateon flagrifer flagrifer (adult 10 cm), the remaining part belong to the in juvenile stages plankton feeding, adult predatory and cannibalic Apateon kontheri and Melanerpeton eisfeldi (Werneburg 1986, 1988a). The adult up to 80 cm long eryopide Onchiodon labyrinthicus as the top predator at the end of the food chains is correspondingly rare. Bedding planes with mass-death layers of fishes or amphibians are most possibly caused by episodic events of complete overturn of the whole water body bringing oxygen depleted and H2S-rich deeper water in the upper water column of the normally thermally stratified lake (Fig. 77). Palaeobiogeography: The typical amphibian association of the Upper Goldlauter Fm., Melanerpeton eisfeldi, Apateon kontheri, and Apateon flagrifer has been discovered in the Alinus lake horizon of the Rio su Luda Fm. in the Perdasdefogu basin of Sardinia, i.e. on the southern flank of the Variscan orogene (Werneburg et al., 2007)! Independent parallel-evolution of 3 species of 2 different genera is absolutely excluded. Both occurrences are only explicable by migrations across the deeply eroded former orogene. The semiaquatic branchiosaurs could cross the Variscian watershed very easily as ”pond hoppers“ via wetlands in the head waters of rivers dewatering in different directions from the drainage divide. See for a modern example the head waters of modern alpine rivers, which are only few kilometres far from one another, e.g. Loire and Rhone as well as Rhine, Po and Danube. Additionally, the species of the Alinus lake belong to the stream ecomorphotype (Fig. 76 D) adapted to flowing waters and therefore equipped with a high migration potential (Werneburg, 2002).

Stop 10: Cabarz quarry, Lower Goldlauter Formation, Sakmarian alluvial plain to temporary lacustrine deposits in red and grey facies Stratigraphy: Lower Goldlauter Formation, Lower Rotliegend, Sakmarian, Early Permian. Location: south of Cabarz, Inselsberg road, active quarry of the Steinbruch Mitteldeutsche Hartstein-, Kies- und Mischwerke. Coordinates: N 50° 52.079'; E 10° 29.373'. For general informations see stop 9. Outcrop situation: The active quarry present the rare opportunity for sedimentological and palaeontological investigations of large scale exposed Early Permian floodplain and lake deposits with

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transitions from red to grey facies and is in this regard singular in Europe. Research work in cooperation of the TU Bergakademie Freiberg with the Museum of Natural History, Schleusingen, and the National Geopark Thüringen, is in progress (MSc mapping and thesis) and well supported by the quarry owner. Exposed from the 1st to the 3rd quarry floor are alluvial plain to flood plain deposits (Fig. 78), mainly greenish to grey sandstones and siltstones with transitions from fluvial to subaquatic-lacustrine facies. Intercalated are several decimetre to metre thick pelitic pond and lake sediments. Typical are varved dark green to black, silt and claystones, often carbonatic and rich in organic carbon. Based on the fossil content, they could be classified as deposits of short termed branchiosaur-lakes and temporary ponds. One of those horizons starts with decimetre thick finely varved black shales immediately above a metre thick (?)reworked pyroclastit and merged continuously into increasingly wider spaced laminites of silting up deposits. Most possibly this profile represent a restricted amphibian pond in the extended shallow littoral of a larger (fish-type) lake. Interesting are metre thick slumping horizons, eventually generated by earthquakes during the very active volcanism of this time. Fig. 78. Lower Goldlauter Fm., Cabarz quarry, profile from floor 2a (1–3) up to floor 4 above the intrusive andesite. A: 1 – decimetre thick horizon of greenish-greyish to brownish claystone laminites of the pelagial with mass occurrences of branchiosaurs and conchostracans layers (B – polished cross section); 2 – transition from laminites into in centimetre scale, higher up in decimetre scale fine bedded greenish to beige siltstones of the litoral during the silting up phase of the lake; 3 – fluvial sandstones of a main channel; 4 – wet red beds of the flood plain facies with soil horizons. (Photos M. Hübner).

A

B

Fossil content: Amphibians: the branchiosaur A. dracyiensis dominates with 90%; the remaining 10% are represented by the very rare Schoenfelderpeton prescheri and Branchierpeton reinholdi. Interestingly, Apateon dracyiensis appears here as the stream ecomorphotype (see stop 9 and Fig. 76 D). Mass death layers of mainly juvenile branchiosaurs are common (Fig. 77). Aquatic invertebrates: conchostracans, ostracods and the wingless insect Dasyleptus (Fig. 80) in the grey facies; in the reddish-grey littoral deposits and in former puddles of the more fluvial red beds between the lake horizons occur occasionally triopsides and more common their typical traces (Isopodichnus and Rusophycus or Cruziana respectively) besides conchostracans. First Medusina limnica were found here in the profile of the Thuringian forest basin. Terrestrial fauna: in some layers insects could be very common, mainly blattids (cockroaches; Fig. 79) besides rarer grylloblattids and very rare orthopterans. With the insect finds from the Sperbersbach excavation in the same stratigraphic level, both together represents now with more than

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2,000 specimens the richest Early Permian entomofauna in Eurameria, comparable to the famous but somewhat younger Obora entomofauna (Early Kungurian) in the Czech Boskovice graben. Plants: Most common in number and species richness are conifers (walchians and broad leaved cordaits) as well as seed ferns (Autunia conferta, Arnhardtia scheibei, Dichophyllum flabellifera, Odontopteris lingulata, Sphenopteris germanica, etc.). For details see Barthel (2003–2008).

Fig. 79. Sysciophlebia balteata; Lower Goldlauter Fm., Cabarz quarry (photo St. Brauner).

Fig. 80. Wingless aquatic insect Dasyleptus, Lower Goldlauter Fm., Cabarz quarry (photo St. Brauner).

Transitional to the 3rd quarry floor higher up in the profile appear on the 4th and 5th quarry floor wet red beds of flood plain to alluvial plain facies with sandy channel deposits (major and minor channels) as well as overbank fine clastics. Typical are Scoyenia and Planolites montanus ichnofacies, vertisols and very immature clacisols with violet-greenish-whitish colour mottling, flood marks, desiccation cracks and heavy rain marks. Distinct bedding planes exhibit large walchian twigs in the so called “muddy preservation”, obviously washed together during heavy rain storms and saddled down in ponds on the flood plain during waning flood. Tetrapod tracks are common (Limnopus, Amphisauropus, Ichniotherium, Dimetropus, Dromopus); only one times a (head less) 30 cm long skeleton of an araeoscelide reptile was found. Channel fills with calcic nodules from reworked soils contain in places isolated tetrapod bones. If time permits and depending on the current situation in the quarry we will have a short visit in the eastern part of the quarry, where the basal Rotliegend transitional Gzhelian/Asselian Ilmenau Formation is exposed. There, lacustrine sediments contain interesting debris flows, and fluvial channel deposits bear stromatolits, primary growing around huge tree trunks.

Stop 11a: Tambach Formation, Early Permian Wadi fill Stratigraphy: Tambach Fm., Upper Rotliegend I, Early Permian Artinskian/Kungurian transition. Location: Valley of the river Schmalwasser, south of Tambach-Dietharz, Oberhofer road. Coordinates: N 50° 47.091'; E 10° 38.134'. Stratigraphy: Lower (Bielstein-) Conglomerat Member, lateral and vertical transition into medial alluvial fan facies of the Tambach sandstone Member. For details of the Tambach Formation see stop 11b. Outcrop situation: The stop exhibits the fill of a wadi incised during Rotterode Formation times into volcanites of the NW slope of the Oberhof Volcanite Complex (Lützner, 1987, 1988). The steep, nearly vertical flanks of the wadi are partially exhumed by modern erosion. Exposed are proximal very coarse grained conglomerates with oversized blocks (up to 1 m diameter) inside the wadi and at the wadi mouth (Fig. 81 A). Along the road from the wadi mouth into the town Tambach the transition from proximal debris flow dominated alluvial fan deposits into increasingly better organised and sorted hyperconcentrated flash flood deposits of a braid plain could be traced (Fig. 81 B). Sediments of the flood basin are only 2.5 km far from the wadi mouth exposed in the Bromacker quarries at stop 11b.

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A

B

Fig. 81. Fan deposits of the Artinskian/Kungurian Tambach Fm., Schmalwassergrund at Tambach; A – stacked debris flow deposits at a wadi mouth with oversized blocks, about 2.5 km south of the floodbasin at the Bromacker; B – increasingly better organized stacked debris flows and hyperconcentrated flows of the alluvial plain with decreasing grain sizes distal of the wadi mouth.

Stop 11b: Bromacker, Tambach-Dietharz, singular Early Permian tetrapod locality (Fig. 82) Stratigraphy: Tambach Fm., Upper Rotliegend I, Early Permian Artinskian/Kungurian transition. Location: building stone quarry south of Tambach-Dietharz at the Bromacker. Coordinates: N 50° 48.602'; E 10° 37.292'. Thickness: maximaly 280 m. Base: Lower Tambach conglomerate, erosiv above the Rotterode Fm. and older sediments as well as on the Oberhof Volcanite Complex and older. Top: (?) basal conglomerate of the Eisenach Fm. (Wachstein conglomerate) Biostratigraphy: insect remains: Moravamylacris kukalovae-intervall, about Late Wolfcampian to Early Leonardian (Schneider et al., 1988); conchostracans: Lioestheria monticula-zone (Martens, 1987); vertebrates: Saymouria sanjuanensis-level, Late Wolfcampian (Berman & Martens, 1993); seymouran land-vertebrate faunachron (LVF) which ”straddles the Wolfcampian-Leonardian boundary“ after Lucas (2006). Isotopic ages: because of seemingly missing pyroclastics in the Tambach Fm. no isotopic age is available.

Lithology/facies: The pure red beds of the Tambach Formation have been deposited in an S-N stretching depression on and at the flanks of the Oberhof Volcanite Complex; drainage was possibly to the North into the Saale basin (Lützner et al., 2012). Simplified, the formation starts with up to 125 m alluvial fan conglomerates (Bielstein conglomerate Member), which grade lateral and vertically into the up to 100 m thick Tambach sandstone Member. Tectonical activity caused the progradating of a new alluvial fan and braid plain system, the up to 50 m thick upper conglomerate (Finsterbergen conglomerate Member). The basal conglomerates were deposited as debris flows and hyperconcentrated flash flood-flows. The upper conglomerate represents shallow alluvial fans with transitions into a braid plain environment. Regardless the longer transport distances from a crystalline and granitic source (Ruhla Crystalline Complex) the roundness of the pebbles is much lower than in the basal conglomerates. The fossiliferous Tambach sandstone originates in an alluvial braid plain environment. Typical are flat channels and sheetflood bodies with intercalated short-termed pontic claystones and siltstones as well as lateral and vertical transitions into floodplain siltstones. Horizons rich in mud clasts and containing articulated tetrapod skeletons result from repeated catastrophic flood events.

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B

A

C

Fig. 82. Tambach Fm., Artinskian/Kungurian; A – generalised profile of the Bromacker quarry and excavation site at TambachDietharz (after Martens, 1988, 2001); 0 m to 4.7 m – upper part of Tambach sandstone, 4.7 m to 8.6 m – Bromacker siltstones, 8.6 m to 9.0 m – first coarse clastics of the Upper Tambach conglomerate; B – about 2 m high slab of the Tambach sandstone with Ichniotherium tracks and scratch marks crossed by desiccation cracks (disposed in front of the Geological Institute, Freiberg); B – the enigmatic invertebrate trace Tambia spiralis, diameter 2 cm.

Outcrop situation and interpretation: Exposed in the quarry areal are the Tambach sandstone Mb. with the Bromacker siltstones in the top. The mostly well sorted fine to middle grained sandstones form stacked decimetre to metre thick internally indistinct horizontal plane to rarer distinct small to large scale trough bedded horizons. The single sandstone bodies fill elongated decameter long shallow channels. Decimeter deep and meter wide gutter casts are common. Single beds are mostly separated by centimeter thick desiccation crack horizons of mud drapes. Those features indicate that these single sandstone beds correspond to single flood events. The mud drapes are settled down after floods. They contain a variety of tetrapod tracks, invertebrate traces and in places the freshwater jellyfish Medusina limnica. The tracks and traces were later dissected by desiccation cracks. Concentric and parallel water level marks in about 0.5 cm to 1 cm distance from one another are interpreted as the result of strongly changing day/night (noctidiurnal) temperatures and therefore evaporation rates as known from modern semiarid to arid climates. Counting of those marks result in time durations of 30 to 100 days of water fill of those puddles and ponds. The about 4 m thick Bromacker siltstones are dominated by two facies: about 1.5 m 2 m basal, decimeter-scaled massive siltstones to very fine-grained sandstones, which are sharply overlain by beds of finely laminated siltstone and claystone. Essentially all of the hundreds of vertebrate skeletal specimens collected from the Bromacker, ranging from isolated elements to partial and complete, articulated skeletons were recovered from two closely associated sheetflood deposits within a stratigraphic interval of 1.2 m within the massive clay pebble containing siltstones. The overlying facies of very finely interlaminated siltstone and claystone beds, up to 15 cm thick, have yielded impressions of conchostracans, insect wings, and myriapod fragments (Martens et al., 1981). Altogether these fine clastics were interpreted as an upper-flow-regime sheetflood deposit and waning flood deposits in an

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ephemeral-lacustrine to flood basin setting. The sheetfloods originated in the wadis at the margins of the Tambach Basin and, when sufficiently intense, spread across the low sloping land surface of the basin center. Bedding planes with densely packed adult conchostracans, buried in living position, represent in analogy to modern examples dried up puddles and ponds on the flood plain. The duration of the ontogenetic development of conchostracans from their dry-resistant eggs to adult stages, which takes places in minimally 4 weeks, coincide well with the standing duration of the water bodies in the sandstone facies. (For detailed environment interpretations see Schneider in Martens et al. (1981); Schneider & Gebhardt (1993); Voigt (2002, 2005) as well as with somewhat contrasting and not completely accepted interpretations Eberth et al., 2000). Fossil content: The Bromacker locality became famous for the well preserved and very common tetrapod tracks discovered here since more than 100 years (Pabst, 1895; for details see Voigt, 2005). In 1974 the first tetrapod bone was discovered by Thomas Martens, since then more than 25 complete skeletons have been excavated by a German – North American team (Martens, Berman, Sumida, Henrici) and documented in numerous publications (see Voigt et al., 2007, 2010). With respect to its unique finds of tetrapod tracks and skeletons, the Bromacker locality has consequently emerged to one of the most important sites of Late Palaeozoic vertebrates in Europe. It is also the place with the first well-documented species-level identification of tetrapod tracks and track makers among Palaeozoic vertebrates: Ichniotherium cottae as the tracks of Diadectes absitus, and Ichniotherium sphaerodactylum as the tracks of Orobates pabsti (cf. Voigt et al., 2007).       

flora dominated by walchians and Calamites gigas; callipterids are very rare; aquatic invertebrates: Medusina limnica, conchostracans form in places mass occurrences; terrestrial invertebrates: relatively common for red beds wings of blattids (Moravamylacris kukalovae, Phylloblatta sp.) and one 8 cm long (?)orthopteran wing fragment, not rare diplopods, rarely arachnids; very common invertebrate traces, such as Tambia spiralis (Fig. 82 C), Striatichnium bromackeri, Scoyenia gracilis; skeletons of amphibians: Tambachia trogalla, Seymouria sanjuanensis (Fig. 83), Orobates pabsti, Diadectes absitus and a dissorophoid amphibian; skeletons of reptiles: Thuringothyris mahlendorffae, Dimetrodon teutonis, Eudibamus cursoris and caseids; tetrapod tracks: Ichniotherium cottae, I. sphaerodactylum, Dimetropus leisnerianus, Varanopus microdactylus, and Tambachichnium schmidti.

Fig. 83. Seymouria sanjuanensis from the Bromacker excavation in the typical preservation of articulated skeletons ”standing“ in the sediment; Museum der Natur, Gotha, No. MNG-10553+10554; described by Bermann et al. (2000). (Photo T. Martens).

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Palaeoclimatology: Postulated is a strong seasonal semiarid climate (conifers and the xeromorphic Calamites gigas). Rainy seasons with high rates of rainfall, eventually up to 1000 mm/a, could be assumed compared to modern examples in the arid savannas of Middle America (see Martens et al., 1981; Roscher & Schneider, 2006). But evaporation and run off exceeds precipitation as indicated by the missing of evaporates and the 30 to 100 days standing water bodies in ponds and pools. Common heavy rainfall is supported by the facies pattern of the Tambach sandstone (see above) and the mudflows in the Bromacker siltstone. Rooted soils, vertisols, and immature calcisols as well as weekly developed groundwater calcretes, and especially the very common invertebrate burrows point on a fluctuating groundwater level. After the first appearance of playa-like red beds in the upper Oberhof Fm. and in the Rotterode Fm., the Tambach Fm. was seemingly deposited in a somewhat wetter climate as before. Eisenach Fm. (see stop 12). Supported by biostratigraphic data this level could be correlated with the Rabejac Fm. of the Lodève basin, the Sobernheim lake deposits of the Nahe Subgroup in the Saar-Nahe basin, and the Bacov-Obora lake deposits in the Boskovice graben amongst others (Fig. 4 and Fig. 5). The following Eisenach Fm. (with the exception of Claystone 1) displays with evaporitic playa deposits a dryer climate as before. Therefore the level of the Tambach Fm. and their correlatives are regarded as the Late Artinskian/earliest Kungurian wetphase E by Roscher & Schneider (2006).

Stop 12: Eisenach Formation, Wartburg castle, late Early to early Late Permian dry red beds of alluvial fan to evaporitic playa deposits The Wartburg is a castle originally built in the Middle Ages, situated on a 410 metres (1,350 ft) precipice to the southwest the town of Eisenach. Wartburg Castle, the best preserved castle of Romanesque style in Germany, was added in 1999 by the UNESCO to the World Heritage List. The castle's foundation was laid about 1067 by the Thuringian count of Schauenburg, Louis the Springer (Ludwig der Springer), later his son Louis I was elevated to the rank of a Landgrave in Thuringia. It was the home of St. Elisabeth of Hungary. Martin Luther (secretly under the name of Junker Jörg) translated here the New Testament of the Bible into German.

Stratigraphy: Eisenach Fm., Upper Rotliegend I, Early Permian Kungurian to ?Roadian/Wordian transition. Location: castle Wartburg near Eisenach. Coordinates: N 50° 57.983'; E 10° 18.381'. Thickness: 400 m to 600 m. Base: Wachstein conglomerate. Top: basal conglomerate of the Upper Rotliegend II Neuenhof Fm. (“Grenzkonglomerat”). Biostratigraphy: conchostracans: Pseudestheria wilhelmsthalensis - zone (Martens, 1987). Magnetostratigraphy: mixed-polarized interval near the base (Menning, 1987). Isotopic ages: because of seemingly missing pyroclastics in the Eisenach Fm., no isotopic age is available. Lithology/facies: Palaeogeographically, the Eisenach Formation represents the marginal facies in the northeastern part of the SW-NE trending Saar-Werra-Basin. The clastic input is derived from Variscan deformed basement elevations, mainly from the Ruhla Crystalline Complex, in the back of the alluvial fan belt. The main transport vectors are S and SW directed (Lützner, 1981; Lützner et al., 2012). On a large scale the Eisenach Fm. shows a simple lithologic structure. Complexes of coarse-grained conglomeratic deposits alternate with sections dominated by silt- and mudstones. The 80 to 180 m thick conglomerate members of the Eisenach Fm. are interpreted as sheetflood dominated alluvial fan deposits (Lützner, 1981; Lützner et al., 2012). The 20 to 90 m thick sandy siltstone members (so called Tonsteine) include deposits of a more diversified setting. In the main it concerns finely clastics of extended mudflats in front of the fan belt. Relating sediments are inferred from slacking sheetfloods, low-energy streamflows and pond-like shallow standing water bodies. Vertisols, haloturbation and patchy sand fabric are common features of the mudflat deposits. Haloturbated structureless fine sandy silts bear in surface outcrops hollows after gypsum crystals. Centimeter to decimeter, in places meter thick pure claystones appear often in top of fanglomeratic debris flows and hyperconcentrated flows, representing short termed standing water bodies after flood events. Aeolian transport is indicated by well to ideally rounded coarse sand grains (2–3 mm diameter) in the matrix of the fanglomerates. The interfingering and the partially sharp boundaries between conglomerate and siltstone members as well as the occurrence of several meter long dewatering dykes indicate synsedimentary activity of the basin fringe (Lützner, 1994).

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Fossil content: Hitherto, fossils are only known from the lowermost shale member, the Tonstein 1. Conchostraca, arthropod trails, tetrapod tracks, and imprints of Medusina limnica has been described so far (Martens, 1983; Walter, 1983; Werneburg, 1996a). Voigt & Rößler (2004) report the first plant remains, taeniopterid-type leaf fragments. Higher shale members (Tonstein 2 to 5) contain in the best case Medusina limnica, often together with mm-large halite crystal marks. Palaeoclimate: In summary, the Eisenach Formation represents in facies architecture and sedimentological features the type of dry red beds in an evaporitic playa environment (Schneider & Gebhardt, 1993). The lowermost siltstone member, the so called Tonstein 1, may still belong to the vanishing wet phase E of the Tambach Formation and their correlatives (Fig. 4). Higher up the Kungurian dry phase is well expressed as it is reported from the Octon Member of the Salagou Formation in the Lodève basin too (Schneider et al., 2006). Outcrop situation: At the parking place and along the road cuts at the food of the Wartburg castle a typical siltstone member (Tonstein 2) with the overlying Wartburg conglomerate Member is well exposed. The facies association consist of proximal fan deposits dominated by fanglomerates and hyperconcentrated debris flows of angular granitic clast content (supply from the Ruhla Crystalline Complex). Intercalated are haloturbated mudstones. Claystones and siltstones in top of the fanglomeratic beds show mud cracks and contain in places hydromeduses.

A

C

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Fig. 84. Eisenach Fm., Upper Rotliegend I, A – generalized profile of the formation; WSK – basal Wachstein conglomerate, T1 to T5 – siltstone members (Tonstein 1–5), WtK and WbK – Wartburg conglomerate, AK – Aschburg conglomerate, HK – Haupt conglomerate; IR – assumed position of the Illawarra reversal; OR II – Neuenhof Fm.; Z – Zechstein; a – Position of the profile in B; B – profile of upper siltstone member 2 below the base of the Wartburg conglomerate; C – part of the profile shown in B, outcrop at Wartburg parking ground; interbedding of fanglomeratic horizons with claystone layers at the top followed by structureless sandy to pebbly mudstones with patchy sand fabric resulting from vertisol formation and haloturbation. The pure claystones in top of fanglomeratic beds contain Metusina atava (symbol circle with cross) and desiccation cracks. (After Schneider & Gebhardt, 1993).

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6. The Carboniferous – Permian Saale Basin 6.1 Introduction The Saale basin to the SE of the Harz Mountains is the type area for the old miner terms "Rotliegend" (the "rote todte Liegende" = the red dead (barren) rocks below the copper shale) and "Zechstein" (hard limestone in the hanging of the copper shale), as well as the Saalian phase (Stille, 1920). As a lithostratigraphical term, "Rotliegend" has been defined by von Veltheim (1821-1826) and Laspeyres (1875). Referring to this region, the French Lapparent (1883) defined the "Saxonian" and Renevier (1874) the "Thuringian". These terms are still in use as regional “stages” in some parts of western and eastern Europe, but because of poor definition not furthermore in Germany. Coal prospection during the 19th and 20th century and hydrocarbon as well as uranium prospection in the second half of the 20th century form the base of the present knowledge of this region. A geotechnical and scientific highlight was the 1748 m deep, in large parts cored coal-exploration well Schladebach near Leipzig, described in detail by Beyschlag & von Fritsch (1899). Drilled from 1880 to 1886, it was for a long time the deepest drill hole worldwide. After nearly 600 years of hard coal mining in the region of Halle, the last mine closed in 1967. Only Lower Rotliegend volcanites and Upper Rotliegend sediments are partially well exposed in surface outcrops. Late Carboniferous outcrops are restricted to the Kyffhäuser Mountain and the deep incised valley of the Saale River to the north of the town of Halle. Therefore most knowledge is based on drilling cores (e.g., Gaitzsch et al., 1998; Schneider et al., 2005c; Gebhardt & Hiete, 2013).

Fig. 85. Reconstruction of primary extension and thicknesses of the Late Carboniferous Stephanian Saale basin based on wells drilled for coal and hydrocarbon exploration (from Schneider et al., 2005).

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Basin development and basin fill (Figs. 85, 86): The Late Carboniferous Stephanian (Kasimovian) to Middle Permian Upper Rotliegend-I (Kungurian) Saale basin is a continental basin of 150 km length and 90 km width (Schneider et al., 2005b). It is situated above the inverted SW-NE striking MidGerman Crystalline Zone (MGCZ) at the outer border of the Variscian fold belt (Fig. 1). Therefore, it represents a “perimontane” rather than an “intramontane” basin. The underlying Visean grey sediments of the up 1,400 m thick continental Klitschmar Formation and the more than 400 m thick Namurian paralic Sandersdorf Formation are only known from drillings in an area to the north of Leipzig (Gaitzsch et al., 2008). Above an angular unconformity, this formation is overlain by grey sediments of the Westphalian Roitzsch Formation, which is only known from a few wells in the area between Leipzig and Wittenberg. The coal-bearing, mainly coarse-clastic rocks of this formation were deposited in a drainage system reaching from the NE border of the Central Bohemian basin (Gaitzsch et al., 1998, Opluštil & Pešek, 1998; Pešek, 2004) to the Variscan fore deep. The development of the Saale basin started with the Stephanian deposits of the Mansfeld Subgroup that rests disconformable on the Viséan to Westphalian sediments and Variscian metamorphic rocks and granites. The basin is contoured by SW-NE striking border faults and is internally structured by NW-SE striking faults (e.g., Finne-Gera-Jachymov fault, Halle fault, Elbe Zone). This fault pattern controls syn-sedimentary block subsidence and corresponding changes in thicknesses and facies architectures. During the early Lower Rotliegend, this tectonism in conjunction with the formation of the Halle Volcanic Complex reduced the size of the sedimentary basin after the deposition of the Mansfeld Subgroup.

Fig. 86. Stratigraphy and lithology of Carboniferous and Permian deposits of the Saale Basin (Schneider & Romer, 2010). For correlation with the global time scale see Fig. 4.

The up to 1.000 m thick Stephanian (Gzhelian/Asselian) wet red beds of the Mansfeld Subgroup are subdivided in three fining-up megacycles, which correspond to formations (Schneider et al., 2005). Near the top of each megacycle occur commonly spatially restricted lacustrine and palustrine grey sediments, which are classified as subformations. The 60 m to 200 m thick Gorenzen Formation starts with grey-violet to red conglomerates that grade into grey and red coloured sandstones. Grey sediments with carbonaceous sandstones and thin impure coal seams of the Grillenberg Subformation occur in distal fan deposits and in local depocentres. The overlying about 400 m thick megacycle of the Rothenburg Formation includes

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dominantly wet red beds of the Scoyenia facies that rest expansively and partially erosive with basal coarse conglomerates on the Gorenzen Formation, the Westphalian Roitzsch Formation, and the Variscan basement. The basal coarse clastics grade vertically into about 30 m thick mesocycles of fluvial and sheet flood conglomerates, alluvial plain sandstones, and siltstones. Calcisols of different maturity are common. Towards the top of the formation, such soils, horizons with calcareous rhizoconcretions, and meter-thick calcretes are increasingly abundant. Near the top appear decimeter thick lacustrine micritic limestones precipitated in ephemeral shallow lakes and ponds with characean algae, gastropods, and aistopod amphibian bones as well as rare palaeoniscid and xenacanthid fish teeth (Gebhardt & Schneider, 1985; Gebhardt, 1988). The fluvial, lacustrine and palustrine grey sediments of the Querfurt Subformation are restricted to the depocentres. The base of the 500 m to 800 m thick wet red beds of the Siebigerode Formation (stop 13) is marked by to the NE forestepping deposition of coarse pebbly quartz sandstones, rich in kaolinized feldspar, that originates from the metamorphosed granites of the Mid-German Crystalline Zone (MGCZ) at the SW border of the basin. Facies architectures comprise alluvial fan to alluvial plain and flood plain/flood basin associations consisting of stacked minor cycles of about 15 m thickness. Stacked coarse fluvial channel and fluvial bar conglomerates as well as sheet flood fanglomerates characterize medial to distal fan environments. The alluvial plain is dominated by trough cross bedded sandstones with intercalated conglomerate channels. Silicified tree logs are found from the western border of the basin (Kyffhäuser Mts.) to the basin centre near Halle. Alluvial plain and floodplain siltstones are developed in Scoyenia facies and characterized by immature vertisols and calcisols. Changes in the sediment colour from violet and greyish-green to grey mark the transition to the coal-bearing grey facies of the up to 300 m thick Wettin Subformation in the depocenters of the upper Siebigerode Formation. Distinctive marker horizons close to the base of the Wettin Subformation are the “Liegende Kalkstein”, a bioclastic bivalve shell bearing oncoidal limestone, as well as the “Untere Muschelschiefer”, a bivalve-rich claystone that could be traced laterally from the grey into the red facies. These lacustrine deposits are followed by grey fluvial sandstones and siltstones of a floodplain/floodbasin facies with back swamps. Coal seams cover only restricted areas of 2 km by 8 km. Lacustrine bioclastic limestones with fish-remains and bivalve-rich claystones of the “Hangende Kalkstein” and the “Hangende Muschelschiefer” form the top of the Wettin Subformation. Based on macroflora and microflora, the Grillenberg Subformation is dated as Stephanian A and the Wettin Subformation as Stephanian C (Schneider et al., 2005). The Wettin Subformation belongs to the Apateon intermedius – Branchierpeton saalensis-zone (Werneburg & Schneider, 2006) and the Sysciophlebia euglyptica – Syscioblatta dohrni-assemblage zone (Schneider & Werneburg, 2006). The lake deposits of the Wettin Subformation bear a diverse fish fauna with fresh water sharks, which are wide spread and typical for the Stephanian of all larger European basins (Schneider et al., 2000). The base of the Rotliegend Halle Formation is defined by the “Kieselschiefer-Quarzit-Konglomerat” (Chert-Quartzite Conglomerate), which interfinger locally with lacustrine black shales of the “Hangende Muschelschiefer”. The about 600 m thick formation is composed of grey and red sandstones to claystones with intercalated horizons of conglomerate and pyroclastic rocks. The formation is dominated by extensive acidic volcanic rocks of the Halle Volcanic Complex with laccoliths (> 1,000 m thickness), lava domes, and rare lava flows (Breitkreuz & Kennedy, 1999; Romer et al., 2001). The following dry red beds Hornburg Formation (stop 14) includes two fining up megacycles, each 200 m thick (Falk et al., 1979; Gebhardt & Lützner, 2012). The first megacycle starts with a 30 m thick quartzite dominated conglomerate followed by 30 m red silt, in places pebbly sandstones. The second megacycle starts again with quartzite-dominated conglomerates that are overlain by bimodal sandstones of fine to medium grained sand and well-rounded coarse sand grains (“Rundkörniger Sandstein”) followed by well sorted fine to medium grained sandstones (“Feinkörniger Sandstein”). These exceptionally well rounded and sorted grains are unquestionably the result of aeolian saltation transport. Vertically these sandstones grade into playa siltstones and claystones with locally up to two meter deep desiccation cracks. The playa deposits are characterised by the freshwater jellyfish Medusina limnica and diverse arthropod and rare tetrapod tracks (Walter, 1982; Schneider & Gebhardt, 1993). Facies pattern, sequence and climate stratigraphy indicate a lower Upper Rotliegend II age, magnetostratigraphy support a post-Illawara deposition (Gebhardt & Lützner, 2012). After a hiatus follow the up to 100 m thick Upper Rotliegend II Eisleben Formation (stop 15), which is regarded as equivalent to the Hannover Formation of the Southern Permian Basin (cf. Legler, 2006). The braided river, sheet flood and wet to dry sand flat deposits belong to one of the large N-S striking extended wadi systems that delivered the material for the up to 2,400 m thick fill of the Southern Permian Basin. In this regard, the sediments of the Eisleben Formation belong to border facies of the Southern Permian Basin rather than to the Saale basin.

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The marine Zechstein deposits seal the continental facies of the Rotliegend. During the transgression, reworked Rotliegend sediments form the first marine deposits below the metalliferous black pelites of the Kupferschiefer (copper shale). The Zechstein conglomerate and its sandy equivalents (Weissliegendes) consist predominantly of reworked Rotliegend clastics.

Fig. 87. Kyffhäuser monument, Emperor Frederick Barbarossa; below pebbly sandstones and conglomerates with petrified tree trunks.

Stop 13: Kyffhäuser Mountain, Late Carboniferous Stephanian wet red beds – ruins of a mediaval castle and Kyffhäuser monument – emporer Barbarossa and king Wilhelm 1st (Fig. 87) Stratigraphy: Siebigerode Formation, Mansfeld Subgroup, Stephanian C, Gzhelian. Location: Kyffhäuser monument near Kelbra. Coordinates: N 51° 25.002´; E 11° 6.538´. History: The name Kyffhäuser probably stems from the word "cuffese" meaning head, dome or peak. The settlement of Tilleda at the northern rim was already mentioned at the beginning of the 9th century in the Breviarium Lulli as Dullide, an estate of Hersfeld Abbey. A Kaiserpfalz at Tilleda is attested by the 972 marriage certificate of Emperor Otto II and Empress Theophanu (from Byzanz, nova days Istanbul). A first castle on the hill above the settlement may have been erected by Emperor Henry IV during his conflict with the Saxons. His son Henry V inherited the quarrels and the castle was finally slighted by the Saxon Duke (and later Emperor) Lothair of Supplinburg in 1119. Lothair himself started the reconstruction in his later years and the Reichsburg Kyffhausen was completed under Emperor Frederick Barbarossa. The Kyffhäuser has significance in German traditional mythology as the resting place of Emperor Frederick Barbarossa, who drowned on June 10, 1190 in the Göksu River near Silifke (Turkey) during the Third Crusade. According to legend, Barbarossa is not in fact dead, but sleeps in a hidden chamber underneath the Kyffhäuser hills, sitting at a stone table. His beard has supposedly grown so long over the centuries that it grew through the table (Fig. 33). As in the similar legend of King Arthur, Barbarossa supposedly awaits his country's hour of greatest need, when he will emerge once again from under the hill. The presence of ravens circling the Kyffhäuser summit is said to be a sign of Barbarossa's continuing presence. Siebigerode Formation, upper megacycle of Mansfeld Subgroup Thickness: 500 m, in depocentres up to 300 m of them in grey facies of the Wettin Subformation; Base: basin wide deposition of coarse, pebbly arkosic sandstones, rich in kaolinized feldspar, in places erosive on top of the Rothenburg Formation; Top: base of the Kieselschiefer-Quarzit (chert-quarzite) conglomerate at the base of the Lower Rotliegend Halle Formation; Lithology/facies: wet red beds of an alluvial fan/alluvial plain and floodplain/floodbasin system with decimetre thick lacustrine limestones of temporary ponds and shallow lakes as well as calcisols; local grey facies of depocentres as anastomosing river/floodplain association with lacustrine limestones and black shales of perennial lakes as well as palustrine associations with coal seams of back swamp environments; coal seams are restricted to an about 300 km2 large district of the basin centre where they occurs in several isolated areas, each of about 2 to 8 km2 only. Red and grey facies merge laterally into one another on 0.5 km to 1 km distance only.

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Fossil content of the red beds: very common endogenous ichnia of Scoyenia- and Planolites montanus-type; mesophile to xeriphile floral elements as walchians and silicified Dadoxylon trunks; rare arthropod and tetrapod ichnia (Batrachichnus, Limnopus) as well as insect remains; isolated fish and tetrapod microremains in micritic lacustrine limestone horizons together with charophyte gyrogonites, ostracods and gastropods. Fossil content of the grey facies (for details see Schneider et al., 2005b): Bivalves, gastropods, “Spirorbis”, conchostracans, ostracods, merostomata (Pringlia), arachnids, Arthropleura, common insects (mainly blattoids - see Schneider 1978 ff.); diverse fish fauna with actinopterygians, dipnoans, acanthodians, xenacanthid, hybodontid and ctenacanthid fresh water sharks (e.g., Schneider, 1996) as well as rare branchiosaurid amphibians. The typical late Pennsylvanian (Stephanian) flora of the Wettin Formation is dominated by hygrophilous elements of peat-forming forested swamps (such as calamitaleans, sphenophylls, psaroniaceous tree ferns, diverse seed ferns, cordaitaleans and strongly decreasing lepidophytes. Further noteworthy are the appearance of walchian conifers and several mesophilous elements of extrabasinal areas (Kampe & Remy, 1962). Biostratigraphy: based on macro- and microflora (sporomorph zone NBM) Stephanian C (Kampe & Remy, 1962; Kampe & Döring, 1993); based on insects and amphibians Sysciophlebia euglyptica– Syscioblatta dohrni-insect zone or Branchiosaurus saalensis–Apateon intermedius-zone respectively, Stephanian C or middle Gzhelian (Schneider & Werneburg, 2006, 2012); based on xenacanthid shark teeth Bohemiacanthus type Ug-Zone (Schneider, 1984, 1996). Isotopic age: From U/Pb-SHRIMP ages of volcanite intrusions into the Wettin Subformation and the Halle Formation of 297 ± 3 to 301 ± 3 Ma (Breitkreuz & Kennedy, 1999) a 300 Ma age is calculated for the top of the Stephanian C. This is in good agreement with the positioning of this level in the late Gzhelian based on co-occurrences of insect zone species with conodonts in mixed continental/marine profiles (Schneider et al., 2013; Lucas et al., 2013). Palaeoclimate: Wet red beds of the Scoyenia–Planolites montanus-ichnofacfacies, vertisols and calcisols with calcretes, and the predominance of the meso- to xerophilous conifers in the red beds point on seasonal semihumid regional climate with dry phases. Back swamps with hygrophilous floras and lakes in the basin central lowlands result from more humid mesoclimatic conditions generated by feedbacks between precipitation, evapo(transpi)ration, groundwater level, and vegetation cover. Transitions between red and gray facies are observed on 0.5 to 1 km lateral distance only. The Siebigerode Formation marks the start of the Late Gzhelian/Early Asselian wet phase C (Fig. 4) of Roscher & Schneider (2006). Time series analyses of the Mansfeld Subgroup suggest that climatically forced cycles occurred in the order of 400 ka and 100 ka (short and long eccentricity) (Gebhardt & Hiete, 2013). Events: The fish faunas of the upper Mansfeld Subgroup identify the Saale basin as part of an extended European basin system connected by drainage systems (Schneider & Zajiz, 1994; Schneider et al., 2000). Tectonic reorganisation of the basins connected with increased volcanism by around 300 Ma, the so called Franconian event (Schneider et al., 1995), destroys those lake and drainage systems. Lower Rotliegend (roughly Early Asselian) lakes of Europe contain a depleted fish fauna only (Schneider & Zajic, 1994; Boy & Schindler, 2000). This event is indicated in the Saale basin by increasing volcanism and tectonism causing the fast deposition of the “Kieselschiefer-QuarzitKonglomerat” (shert-quarzite conglomerate) at the base of the Lower Rotliegend Halle Formation erosive on top of the foregoing Siebigerode Formation. Outcrop situation: Exposed in the Kyffhäuser area are wet red bed conglomerates, sandstones and siltstones close to the north-western border of the Saale basin (Fig. 85, 86). The outcrop at the Kyffhäuser monument display stacked large scale planar to trough cross bedded fluvial channel bar sandstones and channel conglomerates as well as conglomeratic hyperconcentrated flows and sheet flood fanglomerates of distal fan deposits transitional to an alluvial braid plain environment. Silicified cordaitalean tree logs (Dadoxylon type) are found from the western border of the basin in the outcrop area of the Kyffhäuser down to the basin centre near Halle. Commonly, they occur in flash flood deposits generated by heavy rain storm events. Assumed growing places of the up to 1.5 m thick trees (Fig. 89), representing the upland vegetation (assumed individual age of the trees up to 100 years), are undisturbed areas of mountain slopes (Fig. 88). Alluvial plain siltstones of the Kyffhäuser area are developed in Scoyenia facies and characterized by immature vertisols and calcisols.

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Fig. 88. Reconstruction of the habitat of the cordaitalean trees and the depositional environment of the buried Dadoxylon tree trunks in distal fan and alluvial plain deposits of the Stephanian Mansfeld subgroup (from Gaitzsch, 2001).

Fig. 89. Dadoxylon tree trunks of more than 1 m diameter in flashflood deposits of the Stephanian Mansfeld subgroup; Kyffhäuser Mountain.

Stop (optional): Rothenburg, Late Carboniferous Stephanian red bed deposits Stratigraphy: type section of the Rothenburg Formation (Fig. 86), Mansfeld Subgroup. Location: slope of the Saale river at Rothenburg north-east of Halle. Coordinates: N 51° 38.318´; E 11° 45.081´. Outcrop situation: Well exposed along the river slope are wet red beds of the Rothenburg Formation, the third of the three fining-up megacycles of the Mansfeld Subgroup. The megacycle consists of fining up mesocycles of 35 – 40 m thickness, starting with coarse braided river channel conglomerates, and grading upward into sandstones and siltstones. Common are vertisols and calcisols with calcareous rhizoconcretions as well as mature calcretes of decimetre to meter thickness (Fig. 90). In the cycle tops appear in places temporary lacustrine micritic limestones, containing aquatic gastropods (Fig. 92), ostracods, and disarticulated vertebrate remains. Most possibly, these limestones were produced

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by characeans as indicated by fragments of their internodians and by gyrogonits (Fig. 91; Gebhardt & Schneider, 1985; Gebhardt, 1988).

Fig. 90. Rhizoconcretions below a dm thick calcrete horizon, Rothenburg Fm., Mansfeld Subgroup; slope of the Saale river near Rothenburg.

Palaeoclimate:

Fig. 91. Characean internodians (a – d) and gyrogonites of Stomochara (e – g) from the Mansfeld Subgroup; magnific. a,b – 100x; d – 1800x; e, f, g – 150x; (Gebhardt & Schneider, 1985).

Fig. 92. Freshwater gastropods from temporary lacustrine limestones of the Mansfeld Subgroup.

Stop 14: Rothenschirmbach, Middle Permian playa deposits (Fig. 93) Stratigraphy: Hornburg Formation, ”Feinkörniger Sandstein” (Fine-grained sandstone) and “Blätterton” (Claystone) Members. Location: abandoned Konberg quarry north of village Rothenschirmbach. Coordinates: N 51° 27.467´; E 11° 33.175´. Hornburg Formation Thickness: 525 m; Base: Lower Quarzite conglomerate; Top: basal conglomerate of the Eisleben Formation. Lithology/facies: The Hornburg Formation was deposited contemporaneously to the Middle Permian Parchim to Dethlingen Formations of the Southern Permian basin (Fig. 45). The depositional area was a subdepression in a wadi system superimposed on the former Saale basin and dewatering at times to the North into the Southern Permian basin. The Hornburg Formation consists of two fining up cycles. The first cycle start with the Lower Quarzit conglomerate Member of an alluvial fan to braid plain environment. It is laterally and vertically followed by braid plain (fanglomeratic sheet flood sandstones, debris flows, mud flows) and evaporitic (anhydrite, halite) sand flat deposits of the Blankenheim Sandstone Member. The second cycle starts with Upper Quarzite conglomerate Member. It follows the “Rundkörniger” (well rounded) sandstone Member of 10 m to 60 m thickness. This typical bimodal sandstone consist of fine to medium grained sand and well to ideally rounded coarser grains of 2 mm to 3 mm size. Bedding structures and facies architectures point on a dry sand flat environment with patchy concentrations of saltation transported and therefore well rounded coarse grains. The following “Feinkörniger” (fine grained) sandstone Member represent well sorted fine to medium grained sandstones of primarily aeolian origin and of restricted occurrence. With relatively sharp transition follows the “Blätterton” (laminated claystone) Member consisting of dark red silty claystones, pure claystones and intercalated small scale channel sandstones. Lamination, fossil content and halite pseudomorphs indicate deposition in a playa lake (see below). The superimposed Mischkörniger (mixed grained) sandstone Member, interbeddings of sandstones and conglomerates, represent most possibly a separate cycle.

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The coarse clastics of the Quarzite conglomerates are characterised by common dewatering structures, forming clastic dykes of decimetre width and metre length. Together with the soft sediment deformations in the “Feinkörniger” sandstone Member they are interpreted as earthquake generated structures. This interpretation is well supported by contemporaneous rifting processes (Altmark movements) during the Middle and Late Permian in northern Europe linked with the extrusion of upper mantle basalts in the Southern Permian basin to the North (Schneider & Gebhardt, 1993). Fossil content: very common are arthropod ichnia (Walter, 1982, 1983), rarer are tetrapod tracks (mainly swimming trails) and conchostracans; typical is the hydromedusa Medusina limnica (Müller, 1973). Magnetostratigraphy: The Illawara reversal, detected in the first cycle of the Hornburg Formation by Bachtadse in Gebhardt & Lützner (2012), gives a Middle Permian (Guadalupian, Wordian to Capitanian) for the whole Hornburg Formation. Litho- and cyclostratigraphy: Based on well log correlation and cyclostratigraphy of the Hornburg and Eisleben Formations are correlated with the Parchim and Mirow Formations of the Southern Permian basin (Fig. 45) by Gebhardt & Lützner (2012). Palaeoclimate: The Hornburg Formation bears the typical facies markers of “dry red beds” as follow:  fanglomeratic coarse clastics deposited as debris flows, hyperconcentrated flows and mudflows  aeolian accumulation of fine to medium sand as well as saltation transport of coarse grained sand  (laminated) playa lake claystones with Medusina limnica and/or halite pseudomorphs  layers of evaporites as gypsum and halite  haloturbation and sand patch fabric  gypcretes more common than calcretes  missing Scoyenia- and Planolites montanus-ichnofacies. Semiarid to arid conditions during deposition of the Hornburg Formation are in accordance with the palaeoposition at about 10° north of the palaeoequator and a desert belt stretching across the palaeoequator (Fig. 101; Roscher et al., 2008).

Fig. 93. Abandoned Konberg quarry north of village Rothenschirmbach, Hornburg Fm., Middle Permian (Capitanian); exposed are fluvial redeposited aeolian sandstones superimposed by playa claystones. The well sorted fine to medium grained sandstones display strong postsedimentary deformation structures – see Fig. 94 below.

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Outcrop situation: Exposed is the so called “Fine grained sandstone”, a well sorted quartz sandstone of primary aeolian origin but fluvial re-deposited (Fig. 94). Strong deformations (slumping) of the primary bedding of the sandstones may be related to seismic shocks. Those sandstones are overlain by well bedded red playa lake claystones, which exhibit at the top up to 2 m deep and 20 cm wide clastic dykes, originating from desiccation cracks. It follows siltstones with decimetre thick channel sandstones. Intercalated is a centimetre thick yellowish residual horizon of weathered evaporites, most possibly primarily gypsum. The playa claystones and siltstones contain mm sized halite pseudomorphs together with the freshwater jellyfish Medusina limnica (Fig. 96) and rare conchostracans. Very common are arthropod traces (Fig. 95). Not rare are swimming trails of tetrapods.

Fig. 94. Deformed sandstone, Konberg quarry, Hornburg Fm.

Fig. 95. Insect trails, Konberg quarry, Hornburg Fm.

Fig. 96. Freshwater yellifish Medusina limnica; Hornburg Fm.

Stop 15: Type locality of the "Saalian Phase" of Stille 1924 Stratigraphy: Late Carboniferous Mansfeld Subgroup overlain with an angular unconformity by the Late Permian Eisleben Formation. Location: abandoned quarry in the valley of the Heilige Reiser, Hettstedt, Tal street. Coordinates: N 51° 38.967´; E 11° 31.423´. Outcrop situation (Fig. 97): Exposed are wet red beds, small to medium scale cross-bedded silty sandstones and flaser-laminated siltstones in floodplain facies of the late Carboniferous Mansfeld Subgroup at the bottom of the quarry wall (for details see stop 13). With an angular unconformity follow erosively fanglomeratic coarse clastics of the here Late Permian Eisleben Formation. Eisleben Formation Thickness: increasing from 20 m in the eastern Harz Mountain area in the South to 500 m in the transition to the contemporaneous Hannover Formation of the Southern Permian basin. Base: so called “Porphyrkonglomerat” (rhyolite conglomerate) on top of Late Pennsylvanian to Middle Permian deposits. Top: early Late Permian (Wuchiapingian) transgression sediments (conglomerates and Weissliegend sandstones) of the Zechstein sea. The Kupferschiefer at the base of the Zechstein was dated by Brauns et al. (2003) as 257.3±2.6 Ma, using Re-Os isotopy, and biostratigraphically with the occurrence of the conodont Mesogondolella britannica as early Wuchiapingian (Legler et al., 2005). Lithology/facies: mature quartz dominated braid plain fanglomerates are overlain by sandy to silty sand flat deposits of the dry red bed type. The depositional area is a wadi system superimposed on the former Saale basin. Through several of such wadi systems in the southern foreland of the Southern Permian basin the huge amount of erosional debris was transported into this basin and stacked up to 2500 m thickness in a relatively short time of about 8 Ma. During that time the Southern Permian basin expanded increasingly onto his forelands causing decreasing relief gradients and the deposition of sandy and silty siliciclastics inside the wadis. Fossil content: For the Mansfeld Subgroup see above, stop 13. The sandy to silty upper part of the Eisleben Formation has delivered sparse walchian remains, rarely conchostracans as well as Isopodichnus arthropod and indeterminable tetrapod tracks.

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Magnetostratigraphy: the Eisleben Formation is superimposed on the Hornburg Formation (see above) in which the Illawara reversal has been detected (Gebhardt & Lützner, 2012). Cyclostratigraphy: After Gebhardt & Lützner (2012) the Eisleben Formation represent a marginal facies of the upper Hannover Formation and corresponds to the Dambeck, Niendorf, Munster and Heidberg Members or the fining-up cycles 13/14 to 17, respectively. In relation to the age of the basal sediments of the Zechstein (see above), an earliest Wuchiapingian age for the Eisleben Formation is assumed. Palaeoclimate: see stop 16. The “Saalian phase” problem: According to isotopic ages, biostratigraphic and magnetostratigraphic data the Late Permian (Wuchiapingian) Eisleben Formation overlies the Late Carboniferous (Gzhelian) Rothenburg Formation after a hiatus of roughly 40 Ma (!). Unfortunately, the "Saalian phase" of Stille (1924; see Kunert, 1970) represents at the type locality an addition of the Franconian movements (Stephanian/Lower Rotliegend transition), of intra-Rotliegend tectonic activities, of the Saalian movements (Lower/Upper Rotliegend transition) and the Altmark movements (Upper Rotliegend II). But unquestionably a Saalian maximum of tectonic activity exists! In central Europe tectonic activities culminate between 290 Ma and 285 Ma with last granite intrusions, a maximum of volcanism and relief rejuvenations (Schneider et al., 1995). Basin reorganisations around this time are indicated by several hiatuses in the transition from Lower to Upper Rotliegend I (middle Cisuralian; Fig. 45).

Fig. 97. Type locality of the "Saalian Phase" of Stille (1924); Late Carboniferous Mansfeld Subgroup overlain after an hiatus of roughly 40 Ma by the Late Permian Eisleben Formation with an angular unconformity. Abandoned quarry in the valley of the Heilige Reiser, town Hettstedt.

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7. The Southern Permian Basin 7.1 Introduction Southern Permian basin During the late Middle Permian the SPB was formed as an intracontinental basin in Northern Pangea at palaeolatitudes of 10–15° N. Arid to semi-arid conditions prevailed, leading to deposition in a desert environment (Glennie, 1972; Roscher & Schneider, 2006). The 1700×600 km large SPB stretched from England over the North Sea and Northern Germany to Poland. Approximately 2500 m thick continental sediments were deposited in the depocentre within a period of 6 to 10 Ma. The general facies distribution reveals alluvial deposition at basin margins and a centripetally adjoined belt of dominantly aeolian sediments. In the basin centre a huge saline lake existed (Gast, 1991). The Rotliegend saline lake covered an area of approximately 17,000 km² during lake level lowstands, but doubled to quadrupled its size during wet periods (Gebhardt, 1994) and covered then wide areas of Northeast Germany, Schleswig-Holstein and the North Sea (Fig. 98, A). The Zechstein transgression terminated the continental Rotliegend deposition (Fig. 98, B). Rotliegend sedimentation was controlled by two main parameters, tectonics and climatic fluctuations. Gebhardt et al. (1991) described the Altmark I to IV tectonic movements. They resulted in a restructuring of the basin and triggered the formation of fining upward successions with coarse clastics (fanglomerate or sandstone) at the base of each succession. Moreover the Altmark movements are partly accompanied by the effusion of rift basalts with an upper mantle signature. Climatic variability becomes apparent in lake level fluctuations of the Rotliegend saline lake during the Dethlingen and Hannover Formations (Gast, 1991; Legler & Schneider, 2013). These fluctuations are well pronounced in lake sediments, where claystone was deposited during lake level highstands, and halite during lowstands. At saline lake margins, lake level fluctuations resulted in migrating facies patterns (highstands are represented by lacustrine claystone, sandflats and smaller dunes existed during lowstands). Towards the basin fringe, clayey sandstone, deposited during groundwater-level highstands, can be correlated with lake level highstands. Tectonic activity and climatic variability influenced deposition with variable intensity and frequency. The deposition of the Parchim, Mirow, Dethlingen, and Hannover Formations was controlled by tectonics: the Altmark I movement occurred at the base of the Parchim Formation, the Altmark II at the base of the Mirow Formation and so on. The duration of deposition of each formation can be estimated at 2 to 3 Ma. The Dethlingen and Hannover Formations consist of several members which represent well-pronounced lake level fluctuation cycles. These fluctuations were generated by changing earth orbital parameters (Milankovitch cyclicity; Gast, 1995; Legler & Schneider, 2013). These most remarkable fluctuations correspond to 400 ka variations in eccentricity, which set up the members. However, higher frequency fluctuations (100 ka and 20 ka) within each member are also known. The saline playa lake sedimentation was three times interrupted by short termed marine ingressions from the Palaeo-Arctic trough the Arctic rift system and the Central-Viking-Graben system, identified by marine fauna and Sisotopic values of anhydrite (Legler et al., 2006; Legler & Schneider, 2008). The two first ingressions coincide with sea level highstands in in the Arctic rift system, the last one was possibly triggered by tectonic activity. Thickness: up to 2.500 m; Base: basal conglomerates of the Parchim Formation; Top: marine Zechstein transgression with the deposition of the Kupferschiefer (copper shale) above only centimetres marine reworked Rotliegend sediments in the basin centre. Fossil content: saline playa lake claystones with common Medusina limnica; laminated freshwater playa lake claystones with conchostracans and ostracods; marine ingression horizons with the bivalve Liebea reichei and the fish Acentrophorus. Magnetostratigraphy: the Illawarra reversal detected by Menning et al. (1988) in deposits of the lower Parchim Formation is of Middle to Late Wordian age (267 Ma; Steiner, 2006). Isotopic ages: Kupferschiefer black-shale dated by Brauns et al. (2003) at 257.3±2.6 Ma. Biostratigraphy: Mesogondolella britannica from the Kupferschiefer equivalent in the Southern North Sea (Legler et al., 2005) points to a Wuchiapingian age for the basal Zechstein deposits. Palaeoclimate: The palaeogeographical setting of the Southern Permian basin and his southern foreland at about 10–25° north of the palaeoequator resulted in the influence of an arid to semi-arid climate, leading to deposition in a range of desert environments (Legler & Schneider, 2013). Rotliegend deposition was characterized by alluvial fans and aeolian dunes at the basin margins, with

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evaporitic sandflats in the transition to a salt lake, which covered large areas of the basin center. The salt lake deposits exhibit Milankovitch cycles with frequencies of 400 ka, 100 ka and 20 ka. The 400 ka cycles are interpreted to reflect long-term eccentricity cycles. Meter-scale cycles are interpreted as c. 100 ka eccentricity cycles and c. 20 ka precession cycles (Gast, 1995). The observed fluctuations in precipitation and evaporation rates in the salt lake are interpreted as the result of enhanced or attenuated monsoon intensity triggered by the changes in earth orbital parameters (Legler & Schneider, 2013).

Fig. 98. Mega-playa system of the Southern Permian basin (A) stretching from England over the North Sea and Northern Germany to Poland in an 1700×600 km large area. Approximately 2500 m thick continental sediments were deposited in the depocentre within a period of 6 to 10 Ma. The centre of the basin was mostly covered by a continental salt lake (pink), the border was framed by mud and sandflats as well as dunes. After three short termed marine incursions the basin was flooded by the Zechstein sea (B). Red star indicate the position of the Beber graben-wadi, stop 16. (After Ziegler, 1990).

Stop 16: Bebertal, southern border of the Southern Permian basin (SPB) – the only surface outcrop of this giant mega-playa system Stratigraphy: Middle to early Late Permian Upper Rotliegend II basin fill of the SPB. Location: outcrops in the vicinity of the village Bebertal. Coordinates: quarry Sventesius N 52° 14.397´; E 11° 18.376´ (Fig. 99); outcrop Hünenküche N 52° 13.804´; E 11° 19.145´ (Fig. 100).

Fig. 99. Several generations of stacked dune bases interrupted by reactivation surfaces resulting from water and/or wind erosion. Middle Permian (Wordian to Capitanian) Parchim Fm. at the border of the Southern Permian basin in the Beber graben-wadi system. Qarry Sventesius near Bebertal village; Flechtingen high.

Outcrop situation: Sventesius quarry: Exposed in the lower part of the quarry are pebbly sandstones of a fluvial braid plain overlain by dune sandstones of the Parchim Formation. Reactivation surfaces between the erosion remnants (dune bases only) of several generation of dunes indicate heavy flood discharge through the wadi systems. Depending on the situation in the active quarry, pebbly bedding planes with gutter casts, flood marks and desiccation cracks are exposed. They indicate flowing water between the dunes and interdune ponds. Patchy arrangements of well-rounded coarse sand grains result from saltation transport.

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Hünenküche, eastern slope: Exposed from the bottom to top of the outcrop are dry sand flat deposits of bimodal sandstones. Fine to medium grained aeolian sandstone show single grain layers and strips of well-rounded coarse sand grains resulting from patchy enrichment of saltation transported particles. Partially fluvial reworking is observable. Higher up follow sheetflood deposits of bad sorted pebbly sandstones. On the top of an exposition surface with desiccation cracks and leaching phenomena below, yellowish dune sands with well developed sets of angular planar bed sets appear. They are eroded again by sheet floods. Higher up and to the south in the outcrop dry to wet sandflat deposits crop out. By x-ray log- and lithostratigraphy this part of the profile is correlated with the Mirow Formation (Capitanian).

Fig. 100. Sequence of dry sandflat and sheetflood deposits, overlain by the bases of eroded dunes (yellowish fine to middle grained sandstones). The dunes are deposited on an exposition surface with desiccation cracks and leaching haloes below. To the top follow again sheetflod and small scale braided river deposits transitional to sandflat sediments. Beber graben-wadi at the Southern border of the Southern Permian basin. Late Middle Permian Mirow Formation. Outcrop Hünenküche East near Bebertal, Flechtingen high. (From Legler, 2006).

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8. Synthesis of the excursion The Late Carboniferous and the Permian are characterized on the global scale by a degree of “continentality” that is only known for the last 5 million years of Earth´s history. This character is the result of the assemblage of Pangea. The former Rheic Ocean between the huge landmasses Gondwana and Laurussia closed progressively from east to west (Roscher & Schneider, 2006). The westward fore-stepping of the continental collision caused a more or less continuous formation and erosional destruction of huge mountain ranges along the palaeo-equator. The oldest orogen to the east, the European Variscides, was already eroded down to low mountains by the end of the Carboniferous, when the youngest alpino-type orogen to the west, the Middle Permian AppalachianOuachita belt, was just about to form. Collision and orogeny produced foreland, intermontane, and intramontane basins, at times associated with regionally volumetrically important volcanism. These processes were accompanied by Carboniferous-Permian glaciations of southernmost Gondwana. The storage of water in the south polar ice-cap and in mountain glaciers resulted in a very low sea level. The interplay of the formation of Pangea – with the build-up and erosion of huge mountain chains –, glaciations and deglaciations, and atmospheric changes caused by temporally intense volcanism resulted in the complete disappearance of the equatorial wet tropical belt, which is unique for the Phanerozoic, and its substitution by semi-deserts and deserts (Fig. 101). As shown by Roscher & Schneider (2006), the transition from the late Early Carboniferous (Mississippian) to Middle Permian (Guadalupian) cold-house into the Late Permian-Mesozoic warm-house Earth by increasing aridisation was a process of interchanging wet and dry periods, each of about 7 to 9 Ma duration (Fig. 4, 5). This cyclically increasing aridisation has directly influenced the litho- and biofacial pattern of the Late Carboniferous to Permian basins in Europe as demonstrated during the excursions. The above discussed Czech and German basins are typical Variscan basins, because of their identical geotectonically and climatically governed sedimentary infill and their large scale record of the evolution of biofacies pattern during the Carboniferous and Permian of Euramerica. They are individual, because of their specific position in the Variscan belt, which controls basin formation and size, as well as changes in subsidence pattern and facies architectures during basin development. Furthermore, the onset of sedimentation within a given basin, the temporal distribution of sedimentation hiatuses, and the preservation of the basin fill strongly depends on the setting of this basin. The Early Permian Lower Rotliegend basins fit into a transtensional dextral pull-apart structure that is integrated in the Thuringian-Franconian shear zone along the SW border of the Bohemian Massif. Sedimentation in the Thuringian Forest basin differs from all other basins by recurrent very strong intrabasinal volcanism, producing hundreds of meters thick piles of lava flows, in the Stephanian C to the end of Lower Rotliegend in the Artinskian. During the Upper Rotliegend I, Middle Cisuralian to Middle Guadalupian, all Saxothuringian basins are characterised by vanishing volcanism and the predominance of discontinuously deposited exclusively red beds. The general peneplanation of the Variscan morphogene and the complete filling up of the Variscan basins during this time is interrupted only shortly by local to regional relief rejuvenations. The Upper Rotliegend II (Middle Cisuralian to Early Lopingian) marks the start of a new geotectonical stage in Europe: the transition from the Variscan orogenic era to the post-Variscan platform development, influenced by tectonics and volcanism related to the earliest Pangea break-up and leading to the formation of the Southern Permian basin. This 1,700 km long and 600 km wide intracontinental basin is the embryonic stage of the Mesozoic/Cenozoic Central European basin. In the time before the Southern Permian basin developed, sediment transport was directed concentrically into the local Variscan basins. Fig. 101. Pangean climate model showing the closure of the Rheic ocean accompanied by the vanishing of the everwet tropical biome and the extension of desert and savanna biomes from the Late Carboniferous to the Late Permian. (Models from M. Roscher, unpubl.).

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With the formation of the Southern Permian basin, the erosional debris was transported to the north via huge wadi-systems (Hessen-Saale depression, Eisleben-Bebertal wadi) into this exceptional large intracontinental Middle to Late Permian mega-playa and –sabkha system, which was filled by about 2,500 m of siliciclastic rocks and evaporites in the Upper Rotliegend II and 2,000 m of siliciclastic rocks, carbonates, and evaporites in the Zechstein (Ziegler, 1990; Plein, 1995). The Upper Rotliegend II basin fill is dominated by desert sediments affected by an arid to semiarid climate. Alluvial fans and dunes occur, especially at the southern basin margin, whereas saline lake deposits dominate in the center. The sedimentation was tectonically and climatically controlled. Tectonically driven large-scale cycles are interpreted as formations, whereas the members are climatically governed cycles on a smaller scale (Legler, 2006; Legler et al., 2013). The basin-wide, over hundreds of kilometre correlatable cyclicity of the Southern Permian basin heralds the transition into the post-Variscan platform sedimentation, which start with the very fast flooding of this basin and large parts of the former hinterland by the Late Permian Zechstein sea (Legler & Schneider, 2008). But all this processes from regional to global scale will not be understood without exact time control. Therefore, all colleagues are asked to improve the correlation charts shown below (Fig. 4 and Fig. 5). We know they are still wrong in many details. They will only get better trough good cooperation in the Nonmarine-Marine Working Group.

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