GEOLOGICA BALCANICA, 37. 3—4, Sofia, Dec. 2009, p. 51—57.
Scanning electron microscope and light microscope study of selected palynomorphs from late Miocene sediments of Sofia Basin, Southwest Bulgaria Viktoria Hristova, Dimiter Ivanov Institute of Botany, Bulgarian Academy of Sciences, Sofia 1113, Acad. G. Bonchev Str., Bl. 23, e-mail:
[email protected] (Submitted 03.11.2009; accepted for publication 12.02.2010)
Abstract. This article is focused on pollen morphology of some of the most abundant fossil pollen types from late Miocene sediments in Sofia Basin (Southwest Bulgaria). The investigation includes detail morphological characteristic of the pollen types using observations under light and scanning electron microscope. Materials from the Ñ-14 core near the village of Katina are the subject of this study. The age was determined as middle and upper Pontian on the basis of molluscs and mammals. Three pollen types from gymnosperm plants (Glyptostrobus type, Pinus diploxylon type and Tsuga canadensis type) and ten pollen types from angiosperm plants (Alnus sp., Betula sp., Carpinus sp., Corylus sp., Quercus robur type, Ulmus sp., Liquidambar sp., Juglans sp., Carya sp., Chenopodiàñåàå gen. ind.) have been described.
Hristova, V., Ivanov, D. 2009. Scanning electron microscope and light microscope study of selected palynomorphs from late Miocene sediments of Sofia Basin, Southwest Bulgaria. — Geologica Balc., 37, 3—4, 51—57. Key words: late Miocene, morphology, pollen, SEM, Sofia Basin, Bulgaria. INTRODUCTION First studies on the fossil content of the sediments from the Sofia Basin were provided by Stojanoff and Stefanoff (1929). The authors presented macrofossil data from the Kurilo and Podgumer localities. Following paleobotanical studies dedicated to the composition and structure of the macroflora were published by Stefanoff and Jordanoff (1935), Kitanov (1940, 1956, 1960), Kitanov and Nikolova (1956), Kitanov (1972), Kitanov (1982), Palamarev (1991) and Palamarev et al. (2002). Pollen-analytical studies of the fossil flora are scarce. Only few analyses were carried out mainly for biostratigraphic purposes aiming to precise the age of sediments previously determined with the help of other fossil groups (Kamenov and Kojumdgieva 1983). Some fragmentary information on the pollen flora was published by Drivaliari (1992), Drivaliari et al. (1999) and Jiménez-Moreno et al. (2007). Information on the composition of the microflora and tracing out of its dynamics has been published recently by Íristova and Ivanov (2009a).
Morphological investigations of the fossil pollen from the Neogene sediments in Bulgaria are rare (Ivanov, 1997, 2003; Ivanov et al., 2007). This study is a new contribution to investigation of the pollen morphology. On the basis of the scanning electron microscope and light microscope analyses are made morphological characteristic of some of the most abundant pollen types from late Miocene sediments from Sofia Basin. MATERIAL AND METHODS Studied materials originate from the Ñ-14 core drilled near the village of Katina (42°50'01''N, 23°14'13''E, Google Earth 5.0) (Fig. 1). The sediments belong to the Gnilyane, Novi Iskar and Lozenets Formations. The lithostratigrafic units were defined by Kamenov and Kojumdgieva (1983) and complemented later by Angelova and Yaneva (1998). The section includes sands, sandy clays, silty stratified clays, diatom clays, lignite coals and limestone. The sediments are dated 51
Fig. 1. Geological map of the Sofia Basin (redrawn from Kamenov and Kojumdgieva, 1983). Legend: 1. Quaternary; 2. Lozenets Formation; 3. Novi Iskar Formation; 4. Gnilyane Formation; 5. pre-Neogene rocks; 6. core C-14.
by mammals, molluscs and diatoms as middle and late Pontian (Nikolov, 1985; Ognjanova-Rumenova et al., 2008). The samples are processed according to the standard technique for pollen exraction, namely treatment in 5% solution of Na4P2O7, 10% KOH, heavy liquid and acetolysis according to Erdtman (1966). A total of 75 samples from 6.00 to 262.40 m (at intervals of 1.00 m) are palynologically analysed (Fig. 2). All samples contain well-preserved palynomorphs. The described pollen types belong to the Novi Iskar Formation of Pontian age. Measurements include at least 30 grains carried on each pollen type with light microscope (LM). The pollen diameter, equatorial diameter, diameter of pores are measured and ornamentation of exine are determined for all palynomorphs. The studied materials are kept in the laboratory of “Palaeobotany and pollen analysis” at the Institute of Botany, Bulgarian Academy of Sciences. For scanning electron microscopy (SEM) samples are prepared following standard technique including washing glycerin with destilated water, air-drying and coated with a thin layer of gold. SEM observation and micrographs are made with JEOL GSM 5510 scanning electron microscope. Morphological descriptions are made using guides and atlases of pollen morphology - Faegri and Iversen, 1975; Menke, 1976; Lieux, 1980; Moore and al., 1991; Kohlman-Adamska, 1993; Punt et al., 1994, 2007; Wazynska, 1998; Stuchlik et al., 2001, 2002; Willard et al., 2004, as well as comparative samples from pollen collection of the section of “Palaeobotany and pollen analysis” at the Institute of Botany, Bulgarian 52
Academy of Sciences. Descriptive palynological terminology follows Punt et al. (2007). Following abreviations are used in the text: D-dameter of pollen grain; E-equatorial diameter; P-polar axis. TAXONOMIC DESCRIPTIONS Division PINOPHYTA Family Taxodiaceae Warming Glyptostrobus type Pl. I, Figs 1, 5 Size range: 30—40 μm. Description. Inaperturate pollen grains. Outlines: elliptical to almost round. Exine comparatively thin, about 1 μm. Ornamentation: finely granulate under SEM. Remarks. The established fossil pollen grains are similar to the pollen described by Ivanov (2001) from late Miocene sediments from Southwest Bulgaria. Family Pinaceae Lyndley Pinus diploxylon type Pl. I, Figs 2, 6 Size range of the corpus: 50—70 μm. Description. Bisaccate pollen grains. Outlines of the corpus: elliptical. Aperture: leptome. Sacci: reticulate under observation with SEM. Remarks. The analysed fossil pollen grains differ only by their smaller measurements from the described pollen by Ivanov (1994a).
Tsuga canadensis type Pl. I, Figs 4, 7, 8 Size range: D=72.5—102.5 μm, wide of fringe up to 10 μm. Description. Fringed pollen grains. Outlines: circular. Aperture: leptome. Exine: tectate, plicate. Ornamentation: verrucate on the proximal surface, verrucae large and flattened. Remarks. For their morphological features the analysed pollen is similar to recent T. canadensis shown by Sivak (1973).
Division MAGNOLIOPHYTA Family Betulaceae S. F. Gray Alnus sp. Pl. II, Figs 1—9 Size range: E=22.5—30 μm. Description. 5-(4-)porate pollen grains. Outlines: 5-, 4-angular in polar view. Apertures: pores, equatorial situated. Exine formed compact sections between pores (arcus). This is characteristic of the pollen of the presentatives of genus Alnus. Exine 1.4—1.7 μm
Fig. 2. Lithological column of the core C-14, Katina (after Hristova and Ivanov, 2009b). Legend: 1. sands; 2. silty clayshale; 3. sandy silty clayshale; 4. diatomiceous clayshale; 5. lignite; 6. chalk.
53
thick. Ornamentation: finely granulate at SEM observation and to almost psilate at LM.
rial, diameter of pores 2.0—3.0 μm. Exine 1.3—1.4 μm thick. Ornamentation: scabrate.
Betula sp. Pl. III, Figs 2—3, 6—8 Size range: E=27.5—30 μm. Description. 3-porate pollen grains. Outlines: rounded triangular to almost rounded in polar view. Apertures: pores, equatorial situated, with a vestibulum, diameter of pores about 2.5 μm. Exine 1.5—1.7 μm thick. Ornamentation: finely granulate (SEM) to almost psilate (LM). Remarks. Described pollen grains are bigger than determinated by Ivanov (2001) from late Miocene sediments from Southwest Bulgaria (Sandanski Basin).
Family Fagaceae Dumortier
Carpinus sp. Pl. III, Figs 4, 9 Size range: E=29—37 μm. Description. 3-, 4-porate pollen grains. Outlines: rounded 3-, 4-angular in polar view. Apertures: pores, equatorial situated, with a vestibulum, annulate, diameter of pores 2.4—3.5 μm. Exine 1.2—1.4 μm thick. Ornamentation: almost psilate. Corylus sp. Pl. III, Figs 1, 5 Size range: E=27.5—29 μm. Description. 3-porate pollen grains. Outlines: rounded 3-angular in polar view. Apertures: pores, equato-
Quercus robur type Pl. IV, Figs 1—8 Size range: Ð=25—35 μm, Å=17.5—22.5 μm. Description. 3-colporate pollen grains. Outlines: elliptical in equatorial view, trilobite in polar view. Apertures: ectoapertures colpi, endoapertures pores, equatorial, unclearly visible. Exine: 1.4—2.0 μm. Ornamentation: verrucate. Remarks. This fossil pollen grains do not distinguish from those described by Ivanov (1994b), Stuchlik (1994) and Van Benthem et al. (1984). Family Ulmaceae Mirbel Ulmus sp. Pl. V, Figs 2, 4, 8—9 Size range: D=27.5—40 μm. Description. 4-,5-porate pollen grains. Outlines: rounded 4-, 5-angular in polar view. Apertures: pores, equatorial situated, annulate, diameter of pores 2.0— 3.0 μm. Exine: 1.8—2.4 μm. Ornamentation: rugulate — Faegri and Iversen (1975). Remarks. The described pollen grains differ only by their bigger size than those described by KohlmanAdamska et al. (2004) from the late Miocene sediments from Southwest Poland.
PLATE I Fig. 1. Glyptostrobus — Scanning electron micrograph; Fig. 2. Pinus dyploxylon type — Scanning electron micrograph; Fig. 3. Picea — Scanning electron micrograph; Fig. 4. Tsuga canadensis type — Scanning electron micrograph; Fig. 5. Glyptostrobus — Light micrograph; Fig. 6. Pinus dyploxylon type — Light micrograph; Fig. 7. Tsuga canadensis type — Light micrograph; Fig. 8. Tsuga canadensis type — Scanning electron micrograph, detail of surface. PLATE II Figs 1—5. Alnus sp. — Scanning electron micrograph; Fig. 6. Alnus sp. — Scanning electron micrograph, detail of surface; Figs 7—9. Alnus sp. — Light micrographs. PLATE III Fig. 1. Corylus sp. — Scanning electron micrograph; Figs 2—3. Betula sp. — Scanning electron micrograph; Fig. 4. Carpinus/Ostrya type — Scanning electron micrograph; Fig. 5. Corylus sp. — Scanning electron micrograph, detail of surface; Figs 6—8. Betula sp. — Light micrographs; Fig. 9. Carpinus/Ostrya type — Light micrograph.
54
PLATE I
PLATE II
PLATE III
PLATE IV
PLATE V
PLATE VI
PLATE VII
Family Hamamelidaceae R. Brown in Abel Liquidambar sp. Pl. V, Figs 1, 3, 5—7 Size range: D=37.5—45 μm. Description. Polyporate pollen grains. Outlines: almost rounded, frequently flattened. Apertures: 13—15 pores, rounded to slightly elliptical, diameter of pores 4.5— 5.0 μm; pore membrane granulate. Exine: 1.9—2.1 μm thick. Ornamentation: reticulate, tectum perforate. Remarks. The established fossil pollen grains do not differ from the described by Ivanov (1997) from the Miocene sediments from Northwest Bulgaria. Family Juglandaceae A. Richard ex Kunth Juglans sp. Pl. VI, Figs. 5—6 Size range: D=37.5—45 μm. Description. Polyporate pollen grains. Outlines: rounded to almost round in polar view. Shape oblate (Erdtman, 1966). Apertures: 5—8 pores, diameter of pores 3.1—4.0 μm. Exine: 1.9—2.1 μm thick. Ornamentation: finely granulate to almost psilate. Remarks. The established fossil pollen is morphologically similar to that found in Beli Briag Basin by
Petrov and Draževa-Stamatova (1974) and from the Neogene pollen flora of Central Europe (Stuchlik, 1994). Carya sp. Pl. VI, Figs 1—4, 7—8 Size range: D=42.5—55 μm. Description. 3-porate pollen grains. Outlines: rounded-triangular in polar view. Apertures: 3 pores, equatorial situated, diameter of pores 2.5—3.3 μm. Exine: 1.5—2.1 μm thick. Ornamentation: almost psilate. Remarks. The established fossil pollen grains differ only by their bigger measurements from those described by Ivanov (2001) in late Miocene sediments of Southwest Bulgaria. Family Chenopodiaceae Less. Chenopodiàñåàå gen. indet. Pl. VII, Figs 1—7 Size range: D=17.5—25 μm. Description. Polyporate pollen grains. Outlines: rounded. Apertures: 22—26 pores, equally arranged on the whole pollen grain, rounded; diameter of pores 2—3 μm. Exine: 0.5—0.8 μm thick, tectate-perforate. Ornamentation: psilate.
PLATE IV Figs 1—4. Quercus robur type — Scanning electron micrograph; Fig. 5. Quercus robur type — Scanning electron micrograph, detail of surface; Figs 6—8. Quercus robur type — Light micrographs. PLATE V Fig. 1. Liquidambar sp. — Scanning electron micrograph; Fig. 2. Ulmus sp. — Scanning electron micrograph; Fig. 3. Liquidambar sp. — Scanning electron micrograph, detail of surface; Fig. 4. Ulmus sp. — Scanning electron micrograph, detail of surface; Figs 5—7. Liquidambar sp. — Light micrographs; Figs 8—9. Ulmus sp. — Light micrographs. PLATE VI Figs 1—2. Carya sp. — Scanning electron micrography; Fig. 3. Carya (Juglans?) sp. - Scanning electron micrography; Fig. 4. Carya sp.- Scanning electron micrograph, detail of surface; Figs 5—6. Juglans sp. — Light micrograph; Figs 7—8. Carya sp. — Light micrograph. PLATE VII Figs 1—2. Chenopodiaceae — Scanning electron micrograph; Fig. 3. Chenopodiaceae — Scanning electron micrograph, detail of surface; Figs 4—7. Chenopodiaceae — Light micrographs.
55
CONCLUSIONS Thirteen pollen types have been analysed using both scanning electron and light microscopy. The main part of plants described in this study belong to mixed mesophytic forests, e.g. Betula sp., Carpinus sp., Corylus sp., Quercus robur type, Ulmus sp., Liquidambar sp., Juglans sp., Carya sp. Tsuga canadensis type belongs to the group of micro-mesothermic floristic elements and together with Pinus diploxylon type probably participate in the mixed coniferousbroadleaf vegetation belt in lower mountain hills surrounding the basin. The Glyptostrobus type and Alnus
sp. were components of the swamp forest palaeocoenoses distributed in the flooded terrains in close proximity of the basin. The only component of herbaceous vegetation registered in current study belongs to fam. Chenopodiàñåàå. More detailed palaeoecological analysis of the fossil pollen flora from the Sofia Basin is under preparation.
Acknowledgements This study is supported by the financial help of the National Science Fund, Ìinistry of Education, Youth and Science (Contract B-1525/2005).
REFERENCES Àngelova, D. Yaneva, M. 1998. New data on the lithostratigraphy of the Neogene in the Sofia Basin. Review of Bulgarian Geological Society, 59 (2), 37—40 (in Bulgarian). Drivaliari, A. 1992. Latitudinal gradient through Upper Neogene vegetation in the Eastern Mediterranean, VIII Intern. Palynol. Congr., Aix-en-Provence, Abstracts, p. 38. Drivaliari, A., Ţicleanu, N., Marinescu, F., Mărunţeanu, M., Suc J.-P. 1999. A Pliocene record at Ţicleni (Southwestern Romania). In: Wrenn J. H., Suc J.-P., Leroy S. A. G. (Eds.), The Pliocene: Time of Change, 103—108. American Association of Stratigraphic Palynologists Foundation, Dallas. Erdtman, G. 1966. Pollen Morphology and Plant Taxonomy. Angiosperms. N. Y., London, Haf. Publ. 553 p. Faegri, K., Iversen, J. 1975. Textbook of pollen analysis. Hafner. N. Y. 295 pp. Hristova, V., Ivanov, D. 2009a. Palynological data of the fossil flora from Sofia Neogene Basin (South-West Bulgaria). Preliminary results. Comptes rendus Academie bulgare Sciences, 62 (3), 379—384. Hristova, V., Ivanov, D. 2009b. Palynological analysis of the Late Miocene sediments from the Sofia Basin (SW Bulgaria). Phytologia Balcanica, 15(3), 305—315. Ivanov, D. 1994a. Spores and pollen found in Miocene sediments from North-West Bulgaria. I. Spores and Gymnosperm pollen. Fitologija, 47, 29—39. Ivanov, D. 1994b. Spores and pollen found in Miocene sediments from North-West Bulgaria. II. Angiosperm pollen. Fitologija, 47, 40—62. Ivanov, D. 1997. Miocene Palynomorphs from the Southern part of the Forecarpathian basin (Northwest Bulgaria). Flora Tertiaria Mediterranea, 6 (4), 1—81. Ivanov, D. 2001. Upper Miocene palynomorphs from the Sandanski Graben (Southwest Bulgaria). Taxonomy: Gymnosperms. Phytologia Balcanica, 7 (1), 3—11. Ivanov, D. 2003. Palynological data on the Miocene flora and vegetation of the Sandanski Graben. Phytologia Balcanica, 9 (2), 197—206. Ivanov, D., Ashraf, A. R., Mosbrugger, V. 2007. Late Oligocene and Miocene climate and vegetation in the Eastern Paratethys Area (Northeast Bulgaria, SE Europe), based on pollen data. Palaeogeography, Palaeoclimatology, Palaeoecology, 255 (3—4), 342—360. Jiménez-Moreno, G., S.-M. Popescu, D. Ivanov & J.-P. Suc. 2007. Neogene flora, vegetation and climate dynamics in Southeast Europe and Northeast Mediterranean. Palaeogeography, Palaeoclimatology, Palaeoecology, 253, 224—241. Êàmenov, B., Êîjumdjieva, Å. 1983. Stratigraphy of the Neogene in the Sofia Basin. Palaeontology, Stratigraphy, Lithology, 18, 69—85 (in Bulgarian). Kitanov, B. 1940. Beitrag zur Kenntnis der Fossilflora von Lozenec in Sofia. Proceedings of Bulgarian Geological Society, 12 (1), 1—28 (in Bulgarian).
56
Kitanov, B. 1956. Über den Typ der Pliozän-Pleistozän-Vegetation in der Ebene von Sofia und das Alter der Ablagerungen von Lozenez. Proceedings Institute of Botany, Sofia, 5, 55—84 (in Bulgarian). Kitanov, B. 1960. Einige fossile Pflanzen aus Sofia. Trudove Varkhu Geol. Bulgariya, Ser. Paleontol., 2, 369—391 (in Bulgarian). Êitanov, G. 1972. New species for the Pliocene flora of Bulgaria. Proceedings Institute of Botany, Sofia, 22, 169—179 (in Bulgarian). Kitanov, G. 1982. New data concerning the composition and type of fossil flora in the Sofia Valley. Fitologiya, 21, 34—43 (in Bulgarian). Êitanov, B., Nikolova, A. 1956. New materials for study of the fossil flora from Lozenets in Sofia. Proceedings Institute of Botany, Sofia, 5, 85—125 (in Bulgarian). Kohlman-Adamska, A. 1993. Pollen analysis of the Neogene deposits from the Wyrzysk Region, North-Western Poland. Acta Paleobotanica, 33 (3), 91—297. Kohlman-Adamska, A., Ziembinska-Tworzydlo, M., Zastawniak, E. 2004. In situ pollen in some flowers and inflorescences in the Late Miocene flora of Sosnica (SW Poland). Review of Palaeobotany and Palynology, 132, 261—280. Lieux, M. 1980. An Atlas of pollen of trees, shrubs and woody vines of Louisiana and other Southeastern states. Part II. Platanaceae to Betulaceae. Pollen et Spores, 22 (2), 191— 243. Menke, B. 1976. Pliozäne und ältestquartäre Sporen und Pollenflora von Schleswig-Holstein. Geologisches Jahrbuch. Hannover. 200 pp. Moore, P., Webb, J., Collinson, M. 1991. Pollen Analysis. Second Ed. Blackwell Sci. Publ., London, 216 pp. Nikolov, I. 1985. A catalogue of Bulgarian tertiary mammal localities. Palaeontology, Stratigraphy, Lithology, 21, 43—62 (in Bulgarian). Ognjanova, N., Yaneva, M., Botev, I. 2008. Paleoecological development of the Neogene Sofia Basin (southwestern Bulgaria) based on sedimentological and paleontological evidence. Geologica Carpathica, 59 (1), 59—70. Palamarev, Å. 1991. Composition, structure and main stages in the evolution of the Miocene flora in Bulgaria. DSc Thesis. Institute of Botany, Bulgarian Academy of Sciences, Sofia (in Bulgarian, unpubl.). Palamarev, E., Bozukov, V., Ivanov, D. 2002. Late Neogene floras from Bulgaria: vegetation and palaeoclimate estimates. Acta Universitatis Carolinae — Geologica, 46 (4), 57—63. Petrov, Sl., Draževa-Stamatova, Tz. 1974. Fossil spores and pollen from the Neogen in Bulgaria. I. Fossil pollen from the Pliocene sediments of the Belobriag Coal basin. Proceedings Institute of Botany, Sofia, 25, 93—111.
Punt, W., Blackmore, S., Nilsson, S., Le Thomas, A. 1994. Glossary of pollen and spore terminology. Utrecht: LPP Foundation. pp. 71. Punt, W., Hoen, P. P., Blackmore, S., Nilsson, S., Le Thomas, A. 2007. Glossary of pollen and spore terminology. Review of Palaeobotany and Palynology, 143, 1—81. Sivak, J. 1973. Observations nouvelles sur les grains de pollen de Tsuga. Pollen et Spores, 15 (3—4), 397—457. Stefanoff, B., Jordanoff, D. 1935. Studies upon the Pliocene Flora of the Plain of Sofia (Bulgaria). Sborn. Bălg. Akad. Nauk., 29, 3—150 (in Bulgarian). Stuchlik, L. 1994. Neogene pollen flora of Central Europe. Part 1. Acta Paleobotanica. Krakow, 93 pp. Stuchlik, L., Zembinska-Tworzydto, M., Kohlman-Adamska, A., Grabowska, I., Wazynska, H., Sadowska, A. 2001. Atlas of
pollen and spores of the Polish Neogene. Volume 1. W. Szafer Institute of Botany, Polish Academy of Sciences. Krakow, 158 ðp. Stuchlik, L., Zembinska-Tworzydto, M., Kohlman-Adamska, A., Grabowska, I., Wazynska, H., Sadowska, A. 2002. Atlas of pollen and spores of the Polish Neogene. Volume 2. W. Szafer Institute of Botany, Polish Academy of Sciences. Krakow, 236 pð. Van Benthem, F., Clarke, G., Punt, W. 1984. Fagaceae. The Northwest European Pollen Flora, 4 (33), 87—110. Wazynska, H. 1998. Palynology and paleogeography of the Neogene in the Polish Lowlands. Prace Panstwowego Instytutu Geologicznego CLX. Warszawa, 45 pp. Willard, D., Bernardt, C., Weimer, L. 2004. Atlas of pollen and spores of the Flora Everglades. Palynology, 28, 175—227.
57
58
