control of terrestrial stabilization on late devonian palustrine carbonate ...

CONTROL OF TERRESTRIAL STABILIZATION ON LATE DEVONIAN PALUSTRINE CARBONATE DEPOSITION: CATSKILL MAGNAFACIES, NEW YORK, U.S.A. STAN P. DUNAGAN* AND STEVEN G. DRIESE Department of Geological Sciences, The University of Tennessee–Knoxville, Knoxville, Tennessee 37996-1410, U.S.A. e-mail: [email protected]

ABSTRACT: Upper Devonian (Frasnian) terrestrial strata of south-central New York contain palustrine and lacustrine carbonate deposited within the well-developed Catskill clastic wedge succession. These nonmarine limestone beds (8–50 cm thick) were repeatedly subaerially exposed and subjected to pedogenic processes. Palustrine features include subaerial exposure surfaces with soil crusts, pseudo-microkarst and microkarst, brecciation, desiccation cracks, horizontal, planar, and circumgranular cracks, and rhizoliths. Lacustrine carbonate sedimentation was derived primarily from biogenically induced precipitation and from degradation of calcified charophyte stems and ostracodes. These deposits accumulated in relatively shallow water depths, probably , 10 m. The results of stable isotope analyses (d13C 5 24.0 to 24.7‰ PDB; d18O from 26.8 to 28.7‰ PDB) reveal covariance between d13C and d18O values. The high degree of covariance (r 5 0.75) suggests that these Late Devonian carbonate lakes were hydrologically closed; high rates of surface-water productivity resulted in the heavier d13C values. Late Devonian carbonate lakes developed as a result of landscape stabilization by the developing rhizosphere. In addition, plants of small to moderate stature functioned as clastic filters, trapped terrigenous clastic sediment along lake margins, and thereby permitted carbonate sedimentation to occur in a system otherwise dominated by terrigenous clastics. These Upper Devonian lacustrine deposits contain the oldest recognized occurrence of ‘‘palustrine’’ facies. The temporal distribution of palustrine carbonate deposits therefore appears limited to postSilurian strata. INTRODUCTION

Palustrine carbonate and terrigenous clastic deposits that display evidence of pedogenic modification are commonly associated with shallow lacustrine and marginal marine settings (Platt and Wright 1992), particularly where dominated by low-energy margins with low gradients (Platt and Wright 1991). Under these conditions, fluctuations in lake level and sea level subject extensive areas of the carbonate substrate to episodic subaerial exposure and pedogenic modification. Palustrine carbonates are recognized by the diagnostic set of characteristics superimposed on the sedimentary fabric resulting from the pedogenic processes. Typical palustrine features include mottling, fenestrae, desiccation and pedogenic cracks, brecciation, nodularization and/or grainification, rhizoliths, coated grains, pseudo-microkarst, and Microcodium (Freytet 1973; Freytet and Plaziat 1982; Platt and Wright 1992; Alonso Zarza et al. 1992; Wright and Platt 1995). Palustrine carbonate facies have been described extensively from the Mesozoic and Cenozoic terrestrial deposits of Europe and the U.S.A. (see review in Platt and Wright 1992, and examples in Gierlowski-Kordesch and Kelts 1994). Our knowledge of Paleozoic palustrine carbonate deposits, however, is restricted to examples from the Permian and Pennsylvanian of Spain (Valero Garce´s 1994a, 1994b), France (Toutin-Morin 1994), Germany (Scha¨fer and Sneh 1983; Stapf 1989), and the U.S.A. (Weedman 1994; Valero Garce´s and Gierlowski-Kordesch 1994; Valero Garce´s et al. 1997; Dunagan, unpublished data). * Present address: Department of Geology and Geography, Austin Peay State University, P.O. Box 4418, Clarksville, Tennessee 37044, U.S.A. JOURNAL OF SEDIMENTARY RESEARCH, VOL. 69, NO. 3, MAY, 1999, P. 772–783 Copyright q 1999, SEPM (Society for Sedimentary Geology) 1073-130X/99/069-772/$03.00

Well-developed palustrine features are present in Upper Devonian (Frasnian) terrestrial carbonate and terrigenous clastic deposits from the Catskill Magnafacies, New York. Facies associations and characteristics indicate a lacustrine depositional setting for these palustrine deposits. We interpret that these Upper Devonian palustrine carbonate and clastic facies represent the oldest known recognized occurrence of palustrine facies. It is the purpose of this paper to: (1) describe the palustrine and lacustrine carbonate facies, (2) interpret palustrine and lacustrine paleoenvironments and the dynamics of carbonate sedimentation, (3) discuss implications for Late Devonian paleoclimate and paleohydrology, and (4) compare the Catskill palustrine features with those developed in younger lacustrine and marginal marine systems, and discuss the temporal distribution of Phanerozoic palustrine carbonate deposits. This study provides new insights into the lacustrine and palustrine carbonate depositional environments present within the Catskill paleoecosystem. The Catskill palustrine carbonates record major changes that occurred within terrestrial ecosystems associated with the Ordovician to Devonian development of the rhizosphere, as well as the resulting sedimentary impact of vascular land plants along paleolake margins. The presence of a rhizosphere and of vascular land plants significantly changed the nature of terrestrial sedimentary environments, thereby allowing a post-Devonian proliferation of both palustrine and lacustrine carbonate depositional systems, primarily as a result of landscape stabilization. PREVIOUS INVESTIGATIONS AND GEOLOGIC SETTING

The Catskill Magnafacies was deposited in the Acadian foreland basin on the western flank of the Appalachian orogen (Faill 1985). In New York, the Catskill is characterized by a generally westward-thinning, coarseningupward, regressive succession dominated by siliciclastic deposits (Gordon and Bridge 1987). These terrigenous clastic deposits were interpreted as representing overbank floodplain (crevasse splay, levee, and floodbasin), soil, and fluvial channel environments deposited across a low-gradient alluvial plain that graded westward into sluggish tidal rivers and estuaries (Bridge and Gordon 1985a, 1985b; Demicco et al. 1987). Although typically sandstones represent deposits of laterally migrating and aggrading single-channel rivers (Bridge and Gordon 1985a), estuarine and tidal sandstone, siltstone, and mudstone–claystone paleosol units dominate in the study area (Fig. 1). Nonmarine carbonate deposits from the Catskill clastic wedge have been discussed only rarely in the literature despite intense interest in this sedimentary succession for over 150 years. Probable nonmarine calcareous beds were first reported by Johnson and Friedman (1969). The first general sedimentologic and stratigraphic descriptions were by Demicco et al. (1987), who examined a single carbonate bed and suggested a freshwater-marsh to shallow-lake setting for the bed. We examined Catskill Magnafacies exposures containing nonmarine carbonate intervals in south-central New York state (Fig. 1). Demicco et al. (1987) and Bridge and Willis (1994) reported that these exposures are in the lower part of the Oneonta Formation (Fig. 2). Three stratigraphic sections were measured and described in detail (Fig. 3). Because of the limited nature of the outcrop exposures, lateral control was poor, although in the Davenport Quarry locality, a single carbonate bed is exposed continuously for over 110 m.

LATE DEVONIAN PALUSTRINE CARBONATES

FIG. 1.—Location map showing the stratigraphic sections studied. The primary stratigraphic sections included Davenport Center (DC) and Schoharie Creek (SC). Samples were also examined from Manorkill Falls (MK).

METHODS

Carbonate strata were described and logged on a centimeter scale using standard field techniques (Jacob’s staff and tape). Paleosols and terrigenous clastic strata enclosing the carbonate deposits were described using the methodology of Retallack (1988, 1990). Root traces and rhizoliths were identified and interpreted in the field according to criteria outlined in Sarjeant (1975), Pfefferkorn and Fuchs (1991), Bockelie (1994), and Driese and Mora (in press). Selected hand specimens were first epoxy-impregnated and then slabbed; standard petrographic thin sections were prepared from these samples and were stained with Alizarin Red S and potassium ferricyanide (Dickson 1965, 1966) to identify dolomite and carbonate phases containing ferrous iron. Standard thin-section petrography was supplemented with cathodoluminescence (CL) petrography using a Citl Cold Cathode Luminescence 8200 mk3 luminoscope, an accelerating potential of 10–12 keV, and beam current of 150–200 mA. In many cases, samples were repeatedly thin-sectioned in order to understand three-dimensional morphology of palustrine features. X-ray radiography of a large limestone slab was performed at the University of Cincinnati for this same purpose. Stable-isotope samples were collected by drilling 0.5–4.0 mg powders of the carbonate micritic matrix from polished thin-section billets using a microscope-mounted drill. Organic matter was removed by roasting at 3808C for 1 hour. Carbonate powders were reacted in a common acid bath at 1208C in 100% H3PO4 and were analyzed using a Finnigan MAT Deltaplus mass spectrometer at the University of Tennessee. The isotopic results are reported in d permil (‰) notation relative to the PDB standard (Craig 1957) and corrected to 258C, with a reproducibility of 6 0.05‰. CARBONATE DEPOSITS

Palustrine Facies This marginal lacustrine facies is composed of three subfacies, including calcareous siltstone to sandstone, carbonate mudstone/wackestone, and intraclast packstone/grainstone deposits. Unit thickness ranged from approximately 8 to 50 cm. Palustrine features common to this facies are well

773

FIG. 2.—Stratigraphic nomenclature for Middle and Upper Devonian rocks in south-central New York, after Demicco et al. (1987) and Bridge and Willis (1994). Lacustrine and palustrine carbonate deposits occur within the lower part of the Oneonta Formation (5 Middle Moscow Formation), which ranges from late Givetian to early Frasnian in age.

developed at the Davenport Center, Manorkill Falls, and Schoharie Creek sections (Fig. 3). Calcareous Siltstone and Sandstone.—These deposits are intercalated with terrigenous clastic, carbonate mudstone/wackestone, and open-water lacustrine deposits (described below). The palustrine clastic units are typically centimeters in thickness (, 10 cm). The sandstone units are massive and contain micrite as a minor matrix component (Figs. 4A, B). The siltstone beds are commonly bioturbated and display rare laminae. The quartz silt to medium sand is angular to subrounded and composed of monocrystalline and polycrystalline quartz with minor feldspar. Disarticulated, thinshelled ostracodes, carbonate intraclasts, fish plates, and macerated plant fragments are present in the calcareous sandstones as well as large, branching rhizoliths and pseudo-microkarst (Fig. 4A). Meniscate burrows (variable orientation, up to 1.0 mm in diameter), articulated, thick-shelled ostracodes, angular micritic intraclasts, and macerated plant and bone fragments are present in the calcareous siltstones (Figs. 4A, B). The siltstones also commonly fine upward. Carbonate Mudstone to Wackestone.—Dolomitic mudstone and wackestone deposits are characterized by skeletal fragments, peloids, and quartz silt and sand, with lesser proportions of intraclasts and rare coated grains. The carbonate matrix consists of dolomicrite (up to 30–40%). Skeletal constituents include charophyte stem fragments, ostracodes (mainly disarticulated and thin-shelled valves), and fish plates (Fig. 5A, B, C). Meniscate and sharp-walled burrows with diameters of approximately 1 cm and lengths up to 6–10 cm are common (Fig. 6). Quartz silt and sand are angular to subrounded and dominated by angular to subrounded, monocrystalline and polycrystalline quartz. The mudstones and wackestones are generally massive in appearance. Framboidal pyrite is also present. Downward, branching rhizoliths are present, and three different informal ‘‘types’’ of rhizolith morphology are recognized. Type I have a clayey micrite to microspar infilling and are characterized by both a vertical and a horizontal component (Fig. 5E). Type II rhizoliths are thin, wispy tubular structures (20–100 mm wide and up to 1.5 mm long), filled with calcite spar, and mainly vertical to subvertical (Fig. 5F). Type III are bifurcatingdownward, sharp-walled rhizoliths filled with quartz silt and sand, peloids, intraclasts, coated grains, and ostracodes (Figs. 5G, H, 6). Pseudo-microkarst (Freytet 1973; Freytet and Plaziat 1982; Platt 1989;

774

S.P. DUNAGAN AND S.G. DRIESE

FIG. 3.— Stratigraphic sections from the east and west ends of the Davenport Center quarry and from the Schoharie Creek locality. Scale is in centimeters.


775

exposures and are represented by a single microfacies. This facies is typically overlain by palustrine deposits, such as calcareous siltstone and sandstone or carbonate mudstone and wackestone. Carbonate Mudstone.—This facies is characterized by lenticular laminae (, 100 mm thick) of alternating micrite and quartz silt (Fig. 8) that are commonly disrupted by rhizoliths and meniscate burrows extending downward from overlying palustrine facies (Fig. 6). Microfaults are also present in this facies. Fossil allochems are not observed in this microfacies. TERRIGENOUS CLASTIC DEPOSITS

Sandstone and siltstone deposits interbedded with the limestone beds are commonly mottled and/or contain rhizoliths (Fig. 3). Sandstone-filled desiccation cracks are also present locally within siltstone units at the Schoharie Creek section, suggesting that episodic flooding of the basin was followed by prolonged dry periods (Fig. 3). An organic-rich siltstone or ‘‘smut’’ deposit containing macerated plant fragments and angular to subrounded quartz silt and fine sand with minor carbonate intraclasts is present at the west end of the Davenport Center quarry section (Fig. 3). Pedogenic features associated with the claystone–mudstone paleosols include: (1) large, penetrating, carbonate-lined rhizoliths, (2) circumgranular cracks, (3) platy, blocky to angular, and rounded to granular peds, and (4) pedogenic slickensides, all of which suggest a strong vertic (shrink–swell) component associated with seasonal wetting and drying. These vertic paleosol features are comparable to those described in the Catskill succession previously by Driese and Mora (1993, in press), Driese et al. (1997), and Mora and Driese (in press). DISCUSSION

Paleoenvironments

FIG. 4.—Photomicrographs of the clastic palustrine facies, Schoharie Creek section. A) Calcareous sandstone with micritic matrix. Fish plates and ostracode valves are present (palustrine facies). Plane-polarized light. B) Calcareous siltstone with micritic matrix displaying a meniscate burrow (palustrine facies). Plane-polarized light.

Alonso Zarza et al. 1992) is associated with the rhizoliths and includes rhizolith traces filled with breccia clasts with geopetal fillings of laminated internal sediment and/or vadose silt, and circumgranular, horizontal, and planar cracks (Figs. 5D, G, H). Four exposure surfaces are recognized (Fig. 3); these surfaces are characterized by brecciated upper surfaces and display minor relief of up to 20 mm (Figs. 6, 7). One exposure surface is overlain by a prominent gray–green clayey siltstone interpreted as a paleosol (Figs. 3A, 7A, B, E). Rhizoliths and desiccation cracks descend downward, with decreasing density, from each exposure surface into the palustrine limestone (Figs. 6, 7A–D, F). Large meniscate animal burrows (described previously) also descend downward through the palustrine limestone and crosscut two exposure surfaces (Figs. 6, 7E). At the Davenport Center quarry section, two of the exposure surfaces were traced laterally over 110 m between the two measured sections (Fig. 3). Intraclast Packstone/Grainstone.—This palustrine subfacies is characterized by dolomicritic, peloidal, and skeletal intraclasts (up to 20 mm in longest dimension), quartz silt, peloids, and skeletal fragments. The intraclasts are angular to subrounded, suggesting limited transportation. The interstices between the intraclasts are filled with quartz silt, peloids, and ostracodes (disarticulated and articulated valves), and charophyte fragments. Open Lacustrine Facies Carbonate mudstone deposits (, 5 cm thick) of this subenvironment were observed from the quarry at Davenport Center and Schoharie Creek

The previous paragraphs have characterized the sedimentologic characteristics of the palustrine and lacustrine carbonate facies associated with the Catskill terrestrial succession. The palustrine and lacustrine carbonate and clastic facies described in this study were deposited in small, shallow, carbonate lakes and ponds that were predominantly freshwater, judging from the lack of evaporites (Fig. 8). We interpret that the palustrine carbonate and terrigenous clastic deposits contain a fauna and flora indicative of shallow, freshwater conditions. The presence of charophyte stem fragments (Fig. 5A–C) in the palustrine carbonate mudstone/wackestone deposits suggests water depths of less than 10 m, on the basis of modern analogs (Cohen and Thouin 1987). The marginal lacustrine setting was characterized by shallow water and an oxygenated water column. The occurrence of an organic-rich bed (Fig. 3) suggests that restricted areas of the lake margin were associated with high organic productivity and reducing conditions favorable for preservation of plant material. The presence of subaerial exposure surfaces, rhizoliths, circumgranular and horizontal sheet cracks, and pseudo-microkarst (Figs. 5, 6, 7) indicate that this marginal setting experienced periods of exposure as a result of relatively shallow fluctuations of lake level (Freytet and Plaziat 1982; Platt and Wright 1991, 1992; Alonso Zarza et al. 1992) . The intraclast packstone/grainstone facies are interpreted as detrital, as opposed to in situ production as a result of pseudo-microkarst-induced grainification (Fig. 7B; Alonso Zarza et al. 1992), judging by their association with disarticulated ostracode fragments, peloids, and quartz silt. Numerous examples of palustrine carbonate deposits characterized by similar lithofacies have been documented from postSilurian continental and marginal marine settings (Table 1). The Catskill Magnafacies (Oneonta Formation) exhibits classic palustrine features similar to those described from the Middle Pennsylvanian Upper Freeport Formation of Pennsylvania (Valero Garce´s et al. 1994), the Upper Jurassic Morrison Formation of Colorado (Dunagan et al. 1996; Dunagan 1998a, 1998b), the Lower Cretaceous Rupelo Formation of Spain (Platt 1989), the Upper Cretaceous–Lower Tertiary of southern France (Freytet 1973; Frey-

776



FIG. 6.—X-ray radiograph from lower part of limestone at Davenport Center Quarry section, which provides a three-dimensional aspect to the burrowing and rhizoliths extending from the palustrine facies across the transition to the laminated openwater lacustrine facies and disrupting the primary sedimentary fabric. Arrows point to two separate exposure surfaces. Note distinct downward, dichotomous bifurcation associated with the rhizoliths, as well as 1-cm-diameter, vertical, meniscate animal burrow that crosscuts the entire bed. The dark (opaque) circular features are saddledolomite-filled rhizolith porosity, and the bright white area near the top is an epoxyfilled fracture. Horizontal field of view is approximately 10 cm.

tet and Plaziat 1982), and the Middle Eocene of Spain (Alonso Zarza et al. 1992). The open lacustrine facies record deposition in the relatively deeper or unoxygenated parts of the lake, as suggested by the abundance of laminae (Figs. 6, 8). This facies was present at Davenport Center and Schoharie Creek, but it is not as abundant as the palustrine carbonate and clastic deposits. The generally sparse occurrences of laminae reflect the intensity of both aquatic bioturbation and pedogenic modification as well as the dominance of marginal shallow-water palustrine facies over open-lake facies. The preservation of primary laminae in this facies suggests that the water column experienced periods of thermal or oxygen-related stratification. The equatorial paleogeographic setting for the Catskill delta (Kent 1985) suggests that thermal stratification was likely and that the high organic productivity levels at the lake margins may have also contributed to anoxic conditions in the bottom waters. The abrupt upward transition from

777

laminated open-water carbonate mudstone into the bioturbated and rooted calcareous sandstone and mudstone/wackestone (Figs. 6, 7) is commonly overprinted with rhizoliths and meniscate burrows. The dynamics of sedimentation in the Catskill carbonate ponds was largely controlled by clastic input into the system. Demicco et al. (1987) noted that Catskill lacustrine carbonate sedimentation was clearly tied to a relative decrease in clastic sedimentation, probably associated with a period of marked regression that followed a Givetian–Frasnian transgression in New York. In many respects charophyte meadows around the margins of Catskill lakes would have functioned like sea grasses (Tucker and Wright 1990) in that the charophytes would have baffled and trapped fine clastic sediments entering the lakes (Fig. 9). With clastic sedimentation muted, carbonate in a lacustrine setting may be derived from four main sources: (1) detrital carbonate derived from upland hinterlands by fluvial systems, (2) biogenic carbonate from the skeletal remains of charophytes and ostracodes, (3) carbonate that is inorganically precipitated, and (4) diagenetic carbonate produced by postdepositional precipitation and/or alteration of carbonate minerals (Kelts and Hsu¨ 1978). Demicco et al. (1987) favored carbonate sedimentation associated mainly with carbonate precipitation on cyanobacterial filaments with secondary calcification of charophytes; they cited cyanobacterial filament molds, the abundance of horizontal cracks developed between cyanobacterial mats, and wavy, ‘‘stromatolitic’’ laminae as evidence for this interpretation. We have also observed evidence associated with cyanobacterial carbonate in the form of rare coated grains. However, we interpret Demicco et al.’s (1987) cyanobacterial filament molds and horizontal cracks associated with cyanobacterial mats as fine root tubules (Wright et al. 1988), and as the products of subaerial exposure and pedogenic processes, respectively (Figs. 7E–H). Calcification of delicate charophyte stems likely provided an abundant source of biogenic carbonate, which readily degraded into micrite. Degradation of ostracode shells also served as a biogenic source of carbonate. Inorganic precipitation represented the other major source of carbonate sediments, whereby carbonate was precipitated as a result of a drawdown in CO2 by the photosynthetic activity of charophytes and possibly by other aquatic macrophytes in the carbonate ponds. Although not a primary depositional source, the palustrine and lacustrine carbonate facies both contain abundant diagenetic carbonate, including ferroan dolomicrite (replaced micrite), ferroan saddle dolomite, ferroan equant blocky calcite, and microspar. Paleohydrology and Paleoclimatology Lacustrine deposits provide valuable archives of continental paleohydrology and paleoclimatology on a fine temporal scale, particularly at midto low latitudes (Gierlowski-Kordesch and Kelts 1994). As such, the lowlatitude occurrence of palustrine facies from the Catskill clastic wedge should provide insights into subtle climatic changes in an equatorial alluvial system, which has been characterized as tropical but seasonally wet to dry (Woodrow 1985; Driese and Mora 1993; Mora and Driese in press) and lacking evidence of major climatic shifts (Gordon and Bridge 1987). Platt and Wright (1992) noted that climatic control exerted a particularly strong effect on the evolution of palustrine depositional sequences and that specific palustrine features can be tied to three climate regimes: sub-arid, intermediate, and sub-humid. Platt and Wright (1992) based these climatic

← FIG. 5.—Photomicrographs of the palustrine carbonate facies, Davenport Center quarry section. A, B, C) Calcified charophyte stem fragment (arrows) that has been compacted and partially replaced. Plane-polarized light. D) Breccia clast with two generations of laminated internal sediment. Note meniscate structure. Crossed polarizers. E, F, G, H) Pseudomicrokarst. E) Pseuodomicrokarst cavities filled with vadose silt (arrows) and vertical, curved, and incipient circumgranular cracks. Plane-polarized light. F) Wispy, tubular rhizoliths that bifurcate downward. Plane-polarized light. G) Crosscutting pseudomicrokarst cavities/rhizoliths. The latest cavity displays a complex fill history of vadose silt, spalled breccia clasts, vadose silt, and ferroan equant blocky calcite cement. Plane-polarized light. H) Rhizolith/pseudomicrokarst developed in a calcareous sandstone. Note branching structure of the rhizolith (crossed polarizers).

778



779

of 170–340 days (Fig. 10). Pond development and lake expansion was probably associated with a distinct wet season. This broad range of hydroperiod and exposure index also implies that the Catskill lakes were probably in a constant state of evolution as they shallowed and each basin eventually filled. The occurrence of the organic-rich smut at the top of the lacustrine interval may represent an upward shift of the hydroperiod to wetter conditions. Stable-Isotope Geochemistry

FIG. 8.—Photomicrograph, in plane-polarized light, of open-water lacustrine laminated carbonate mudstone deposits.

regimes upon the distribution of palustrine features documented in Carboniferous to Quaternary terrestrial sequences from Europe and the United States. Sub-arid palustrine sequences are generally dominated by calcrete development, evaporites, brecciation and nodularization, and laminar coatings, whereas palustrine sequences developed under ‘‘intermediate type’’ climatic regimes show evidence for extensive pedogenic activity (rhizoliths), desiccation and pedogenic cracks, Microcodium, pseudo-microkarst, and microkarst (Platt and Wright 1992). In sub-humid settings, sediment aggradation and long-term water-level oscillations lead to brief periods of emergence, but water tables remain permanently high, thereby producing palustrine sequences characterized by well-developed organic-rich horizons (coals, lignites), channel deposits, and blackened pebbles 6 desiccation cracks and rhizoliths (Platt and Wright 1992). The presence of pseudomicrokarst and microkarst with vadose and internal sediment fills, rhizoliths, brecciation, and desiccation cracks and the lack of evaporites and calcrete horizons in Catskill palustrine sequences (Figs. 3, 4, 5, 7–9) suggest deposition under intermediate to sub-humid climatic conditions. The presence of the organic-rich layer that overlies the palustrine carbonate deposits (Fig. 3) may indicate a transition to more sub-humid climatic conditions over this short stratigraphic interval. Platt and Wright (1992) noted the association between the hydroperiod, seasonality, and exposure features in modern freshwater marshes (i.e., the Everglades), which serve as an analog for ‘‘palustrine’’ limestone-forming environments. Platt and Wright (1992) noted that a freshwater exposure index, similar to the marine exposure index of Ginsburg et al. (1979), could be developed, thereby linking characteristic pseudo-microkarst and exposure features developed on the lacustrine carbonate substrate to hydroperiod and seasonality (Fig. 9). Platt and Wright defined the ‘‘hydroperiod’’ as the number of days the sediment surface remains inundated over the course of the year. Assuming that this model is applicable to the lacustrine carbonate record and that the spectrum of features observed from the marginal lacustrine carbonates of the Oneonta Formation are representative of the average climatic and hydrologic conditions, these lakes had an estimated hydroperiod

A preliminary suite of stable-isotope samples (n 5 10) were analyzed from the Upper Devonian palustrine and lacustrine carbonate deposits. The micrite was chiefly ferroan calcite, with up to 10–30% ferroan dolomite, and the micrite exhibited a nonluminescence to dull luminescence, probably due to the presence of iron, which acts as a luminescence quencher (Machel and Burton 1991). The stable-isotope data obtained from the Catskill nonmarine carbonates are shown on a cross-plot of d13C and d18O values (Fig. 11). The open lacustrine carbonates had d13C values from 24.4 to 24.5‰ PDB, and d18O values from 27.0 to 27.3‰ PDB. The palustrine lacustrine carbonates exhibited greater isotopic heterogeneity as compared to micrite from the open lake facies, with d13C values ranging from 24.0 to 24.7‰ PDB, and d18O from 26.8 to 28.7‰ PDB. The oxygen-isotope composition of primary lake carbonate precipitates reflects the isotopic composition of the water column (Talbot and Kelts 1990; Talbot 1990). Primary precipitates from hydrologically open lakes typically display little or only poorly correlated covariance between d18O and d13C, whereas carbonate precipitates from closed lakes display a characteristic, highly correlated covariance (r . 0.7) (Talbot and Kelts 1990; Talbot 1990). The high covariance reflects evaporative concentration of heavier isotopes in the evolving isotopic composition of lake waters (Platt 1992). The isotope samples from the palustrine carbonates show a covariant trend (r 5 0.75). This high degree of covariance suggests a closed lake hydrology, which is consistent with sedimentological evidence that indicates repeated fluctuations in lake level. Hydrologically closed lakes have been documented in numerous ancient (Platt 1992; Anadoń and Utrilla 1993) and modern (see examples in Talbot and Kelts 1990; Talbot 1990) lacustrine successions. This covariant trend is preserved in the Catskill carbonate precipitates despite the diagenetic alteration of the primary carbonate to ferroan phases. The palustrine carbonates examined in this study are enriched in both d13C and d18O relative to values for Late Devonian pedogenic carbonate samples previously reported by Driese and Mora (1993), Mora et al. (1996), and Mora and Driese (in press) but are significantly depleted in both 13C and 18O relative to Late Devonian marine carbonate (d13C 5 11.5‰ PDB, and d18O 5 23.5‰ PDB; Popp et al. 1986). The d13C values of the Catskill palustrine carbonate are more similar to Late Silurian values for pedogenic carbonate reported previously by Driese et al. (1992), Mora et al. (1996), and Mora and Driese (in press). The more positive d13C values for the Late Silurian pedogenic carbonate were explained by higher atmospheric pCO2 (as compared with the Late Devonian), by inheritance of isotopically ‘‘heavy’’ marine carbon from marine allochems in the soil parent material, by lower organic productivity (related to sparse plant cover), and by an absence of a plant cover that possessed significant root

← FIG. 7.—Photographs of polished slabs and thin-section billets from the palustrine carbonate facies, Davenport Center quarry section. A) Two distinct exposure surfaces (arrows) over just a few centimeters are laterally correlative over 100 m and are associated with desiccation cracks, rhizoliths, and extensive brecciation (cf. Fig. 6). B) Brecciation and soil-crust development associated with a subaerial exposure surface (arrow), and nodularization (n) and grainification (g) of the carbonate substrate due to rooting activity. C) Bifurcating and downward-branching rhizolith. D) Ptygmatically folded desiccation cracks crosscutting an exposure surface (arrow). Note the relief and brecciation along the surface. Rhizoliths from the overlying palustrine unit are also well developed (r). E) Sharp-walled burrow extending from an exposure surface containing the clayey micrite of the overlying paleosol as well as breccia clasts. F) Rhizolith infilled with angular quartz, coated grains, ostracode and charophyte fragments, and plant detritus. Centimeter scale bars in all photos.

780

S.P. DUNAGAN AND S.G. DRIESE TABLE 1.—Examples of Phanerozoic lacustrine systems containing prominent palustrine carbonate facies. Example

Depositional System

Upper Devonian, Appalachian Basin, New York, USA Middle Pennsylvanian, Appalachian Basin, Pennsylvania, USA Upper Pennsylvanian, Appalachian Basin, Ohio, USA Permian, Bas-Argens and Este´rel Basins, France

Distal fluvial Distal fluvial Distal fluvial Distal alluvial plain

Middle-Upper Permian, Basque and Aragoń-Beárn Basins, Spain Upper Jurassic, Western Interior Basin, Colorado, USA Early Cretaceous, Western Cameros Basin, Spain Lower Cretaceous, La Serranıá de Cuenca Basin, Spain Upper Cretaceous-upper Eocene, Languedoc Basin, France Upper Cretaceous-lower Paleocene, Santo Domingo de Silos/Arganza-Talveila Basins, Spain Upper Paleocene-lower Eocene, Uinta Basin, Utah, USA Eocene, Hampshire Basin, England

Alluvial-fan system Distal alluvial Distal alluvial Alluvial system Alluvial and fluvial plains Alluvial and fluvial systems

Eocene, Duero Basin, Spain Eocene, Ebro Basin, Spain Upper Oligocene to Lower Miocene, Molasse Basin, Switzerland Miocene, Madrid Basin, Spain Plio-Pleistocene, Marseilles Basin, France Holocene, Florida Everglades, USA

Alluvial-lacustrine system Paralic to transitional environments Alluvial to fluvial plains Distal alluvial Distal alluvial to open lake Distal alluvial to open lake Fluvial and tufa/marsh Distal fluvial to brackish marsh-lagoon

Basinal Setting

References

Foreland Foreland Foreland Extensional intermontane Strike-slip Foreland Extensional rift Extensional rift Foreland ‘‘proto-foreland’’

1 2 3 4 5 6 7 8 9 10

Foreland Subsiding

11 12

Intraplate Foreland Foreland Intracratonic Synrift Low-lying marsh

13 14 15 16 17 18

Some data are partially derived from Platt and Wright (1992) and Armenteros et al. (1997, Table 1). References: (1) this study; (2) Weedman (1994), Valero Garce´s and Gierlowski-Kordesch (1994), Valero Garce´s et al. (1997); (3) Dunagan (unpublished data); (4) Toutin-Morin (1994); (5) Valero Garce´s (1994a, b); (6) Dunagan et al. (1996), Dunagan (1998a); (7) Platt (1989, 1994); (8) Melendez et al. (1994); (9) Freytet (1973), Freytet and Plaziat (1982); (10) Floquet et al. (1994), (11) Stanley and Collinson, (1979), Wells (1983); (12) Armenteros et al. (1997); (13) Armenteros and Corrochano (1994); Mediavilla et al. (1994); (14) Anadoń (1994); (15) Platt (1992); (16) Alonso Zarza et al. (1992); (17) Arlhac et al. (1994), (18) Platt and Wright (1992).

systems capable of introducing isotopically light soil-gas CO2 to depths greater than 10–15 cm beneath the soil surface. In the case of the Catskill palustrine carbonates, we have clear evidence for significant plant-root penetration of the limestone, in some cases to depths of 10–15 cm from exposure surfaces (Figs. 6, 7), hence, we cannot invoke absence of rooting as a possible explanation for heavier d13C values. The density of rooting also suggests a moderately dense plant cover, although admittedly this is hard to quantify. High rates of surface-water productivity served as the controlling mechanism resulting in the heavier d13C values of the lacustrine and palustrine carbonates due to the photosynthetic activity of charophytes. Surface-water enrichment in 13C has been well documented in both modern and ancient lakes (for review, see McKenzie 1985). The shallow nature of the Catskill lakes combined with high productivity would have resulted in 13C enrichment probably throughout the water column, which is documented by the similarity in d13C values between lacustrine and palustrine deposits (Fig. 11). The micrite produced from the degradation of charophyte stems, the

dominant source of carbonate mud, would have inherited the heavier carbon signature. The d18O values for pedogenic carbonate in Appalachian Basin paleosols have been shown to primarily reflect a diagenetic environment, with more deeply buried samples exhibiting the most negative d18O values (Mora et al. 1996; Mora et al. 1998). The Catskill lacustrine and palustrine carbonate samples have d18O values that are enriched relative to Catskill pedogenic carbonate sampled from other sites on the Allegheny plateau (Mora et al. 1993; Mora and Driese in press) that presumably experienced a similar burial history (i.e., maximum P, T). Temporal Trends in Palustrine Sedimentation Palustrine carbonate deposits have been described more extensively from the Mesozoic and Cenozoic than from the Paleozoic (Table 1). Like their Mesozoic and Cenozoic counterparts, these Upper Devonian palustrine carbonate and terrigenous clastic deposits display characteristic features in-

FIG. 9.—Hypothetical distribution of palustrine and lacustrine features in Catskill carbonate ponds.


781

dolomitic lacustrine crusts associated with the Lower Cambrian Officer Basin of Australia (White and Young 1980; Southgate et al. 1989; Southgate 1994). This suggests an apparent temporal restriction of palustrine facies to shallow-water lacustrine and marginal marine settings of Devonian or younger age. The impact of the Ordovician–Devonian development and evolution of the terrestrial ecosystem and the rhizosphere (Beerbower 1985; Algeo et al. 1995; Driese and Mora in press) on continental carbonate sedimentation is recorded by the Catskill palustrine carbonate deposits. By the Late Devonian, vascular land plants had significantly altered sedimentation dynamics in the terrestrial ecosystem of the Old Red continent, which impacted sedimentation in both marine and lacustrine settings. Landscape stabilization resulting from the evolution of land plants with significant root systems and their subsequent colonization of a relatively barren continental surface (Algeo et al. 1995; Driese and Mora in press), therefore, played an important role in the reduction of clastic influx into lacustrine settings and in the subsequent development of continental carbonate depositional systems (Fig. 9). We hypothesize that older (pre-Devonian) palustrine sequences may, in fact, exist in the geologic record; however, the earliest occurrences of such palustrine deposits, particularly those developed in carbonate facies, would probably be temporally restricted to the post–Middle Ordovician, and more likely post–Early Silurian, in continental successions. Likewise, we hypothesize that the intensity and degree of development of palustrine features would directly correspond to the development of the rhizosphere. FIG. 10.—Hydroperiod and exposure index of Catskill carbonate ponds and lakes (shaded box). The hydroperiod represents the number of days the sediment surface is inundated over the course of the year. The exposure index is the percentage of time the sediment surface is exposed. Based upon the freshwater carbonate exposure index of Platt and Wright (1992).

cluding well-developed rhizoliths, pseudo-microkarst and microkarst with complex vadose and internal sediment fills, brecciation and nodularization, desiccation cracks, and horizontal, planar, and circumgranular cracks, all within close proximity to several subaerial exposure surfaces; the Catskill Magnafacies thus contains the here-to-date oldest reported ‘‘palustrine’’ carbonate facies (Frasnian) from the geologic record. We do not mean to imply that lacustrine deposits older than the Late Devonian entirely lack carbonate facies. On the contrary, Middle–Upper Devonian lacustrine complexes from Greenland (Dam and Stemmerik 1994) and Spitsbergen (Friend and Moody-Stuart 1970) contain minor carbonate facies; however, these deposits apparently lack palustrine facies, or at least no similar features were recognized and described. Marginal limestones have also been described from the extensive terrigenous-clasticsdominated lacustrine deposits of the Middle Devonian parts of the Orcadian Basin (Parnell et al. 1994), but features consistent with a palustrine origin were not reported. Palustrine features also appear to be lacking from the

CONCLUSIONS

(1) The Upper Devonian Catskill Magnafacies (Oneonta Formation) of New York contains the oldest known shallow-water palustrine and lacustrine carbonate deposits from the geologic record. (2) The Catskill carbonate ponds and lakes were characterized by a low biodiversity, shallow water depths (, 10 m), and a highly productive water column; carbonate sediments were derived from biogenically induced precipitation and from degradation of calcified charophyte stems and ostracodes. (3) The palustrine facies exhibit a wide variety of classic features such as well-developed rhizoliths, pseudo-microkarst and microkarst with complex vadose and internal sediment fills, brecciation and nodularization, desiccation cracks, and horizontal, planar, and circumgranular cracks. (4) The palustrine features record subtle variations in paleoclimate from ‘‘intermediate type’’ to ‘‘sub-humid type’’, which correspond to an increasing hydroperiod. (5) Stable-isotope compositions of lacustrine and palustrine carbonates are enriched in 13C and 18O relative to coeval pedogenic carbonate. Isotopic results reveal covariant d13C and d18O values, suggesting these Late Devonian carbonate lakes were hydrologically closed. (6) Terrestrial stabilization of the surface by vascular land plants and

FIG. 11.—Stable-isotope cross-plot of d13C and d18O for depositional carbonate from the Catskill palustrine and lacustrine carbonate facies compared with data from Bloomsburg Formation (Upper Silurian; Driese et al. 1992) and Catskill Formation (Upper Devonian, Sherman Creek and Duncannon Members; Driese and Mora 1993; Mora et al. 1993; Mora and Driese in press) pedogenic carbonate deposits.

782


the rhizosphere by the Late Devonian allowed lacustrine carbonate depositional environments to proliferate and resulted in the development of palustrine facies associated with marginal lake settings due to reduction in clastic influx and pedogenic activity. ACKNOWLEDGMENTS

Study of early Paleozoic terrestrial depositional systems and paleosols at the University of Tennessee was supported by the National Science Foundation (Grant EAR-9418183 to S.G. Driese and C.I. Mora). We appreciate the insightful comments of JSR reviewers V.P. Wright, N.H. Platt, and an anonymous reviewer on an earlier draft of this manuscript. We especially thank J.S. Bridge (Binghamton) for his willingness to point us to the best outcrop sections. We also appreciate the assistance of C.I. Mora (Tennessee), J.M. Elick (Tennessee), and T.J. Algeo (Cincinnati) with field work. We especially thank Dr. Algeo for providing X-ray radiography of a palustrine carbonate sample. REFERENCES

ALGEO, T.J., BERNER, R.A., MAYNARD, J.B., AND SCHECKLER, S.E., 1995, Late Devonian oceanic anoxic events and biotic crises: ‘‘rooted’’ in the evolution of vascular land plants?: GSA Today, v. 5, p. 63–66. ALONSO ZARZA, A.M., CALVO, J.P., AND GARC´ıA DEL CURA, M.A., 1992, Palustrine sedimentation and associated features—grainification and pseudo-microkarst—in the Middle Miocene (Intermediate Unit) of the Madrid Basin, Spain: Sedimentary Geology, v. 76, p. 43–61. ANADOŃ, P., 1994, The lacustrine deposits of the Eocene Pontils Group (eastern Ebro Basin, northeast Spain), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 245–249. ANADOŃ, P., AND UTRILLA, R., 1993, Sedimentology and isotope geochemistry of lacustrine carbonates of the Oligocene Campins Basin, north-east Spain: Sedimentology, v. 40, p. 699– 720. ARLHAC, P., NURY, D., AND BLOT, P., 1994, Plio-Pleistocene continental carbonates of the Marseilles Basin travertines (Provence, southern France), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 357–361. ARMENTEROS, I., AND CORROCHANO, A., 1994, Lacustrine record in the continental Tertiary Duero Basin (northern Spain), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 47– 52. ARMENTEROS, I., DALEY, B., AND GARC´ıA, E., 1997. Lacustrine and palustrine facies in the Bembridge Limestone (late Eocene, Hampshire Basin) of the Isle of Wight, southern England: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 128, p. 111–132. BEERBOWER, R., 1985, Early development of continental ecosystems, in Tiffney, B.H., ed., Geological Factors and the Evolution of Plants: New Haven, Connecticut, Yale University Press, p. 47–91. BOCKELIE, J.F., 1994, Plant roots in core, in Donovan, S.K., ed., The Paleobiology of Trace Fossils: New York, Wiley, p. 177–199. BRIDGE, J.S., AND GORDON, E.A., 1985a, Quantitative interpretation of ancient river systems in the Oneonta Formation, Catskill Magnafacies, in Woodrow, D.L., and Sevon, W.D., eds., The Catskill Delta: Geological Society of America, Special Paper 201, p. 163–183. BRIDGE, J.S., AND GORDON, E.A., 1985b, The Catskill Magnafacies of New York State, in Flores, R.M., and Harvey, M., eds., Field Guidebook to Modern and Ancient Fluvial Systems in the United States: Third International Fluvial Sedimentology Conference, Fort Collins, Colorado, p. 3–17. BRIDGE, J.S., AND WILLIS, B.J., 1994, Marine transgressions and regressions recorded in Middle Devonian shore-zone deposits of the Catskills clastic wedge: Geological Society of America, Bulletin, v. 106, p. 1440–1458. COHEN, A.S., AND THOUIN, C., 1987, Nearshore carbonate deposits in lake Tanganyika: Geology, v. 15, p. 414–418. CRAIG, H., 1957, Isotopic standard for carbon and oxygen and correction factors for massspectrometric analysis for carbon dioxide: Geochimica et Cosmochimica Acta, v. 12, p. 133–149. DAM, G., AND STEMMERIK, L., 1994, East Greenland lacustrine complexes, in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 19–27. DEMICCO, R.V., BRIDGE, J.S., AND CLOYD, K.C., 1987, A unique freshwater carbonate from the Upper Devonian Catskill Magnafacies of New York State: Journal of Sedimentary Petrology, v. 57, p. 327–334. DICKSON, J.A.D., 1965, Modified staining technique for carbonates in thin section: Nature, v. 205, p. 587. DICKSON, J.A.D., 1966, Carbonate identification and genesis as revealed by staining: Journal of Sedimentary Petrology, v. 36, p. 491–505. DRIESE, S.G., AND MORA, C.I., 1993, Physico-chemical environment of pedogenic carbonate formation in Devonian vertic palaeosols, central Appalachians, U.S.A.: Sedimentology, v. 40, p. 199–216. DRIESE, S.G., AND MORA, C.I., in press, Evolution and diversification of Siluro-Devonian root traces: influence of paleosol morphology and estimates of paleoatmospheric CO2 levels, in Gensel, P.G., and Edwards, D., eds., Early Land Plants and Their Environments: Interna-

tional Organisation of Palaeobotany Symposium Volume: New York, Columbia University Press. DRIESE, S.G., MORA, C.I., AND ELICK, J.M., 1997, Morphology and taphonomy of root and stump casts of the earliest trees (Middle to Late Devonian), Pennsylvania and New York, U.S.A.: PALAIOS, v. 12, p. 524–537. DRIESE, S.G., MORA, C.I., COTTER, E., AND FOREMAN, J.L., 1992, Paleopedology and stable isotope geochemistry of Late Silurian vertic paleosols, Bloomsburg Formation, central Pennsylvania: Journal of Sedimentary Petrology, v. 62, p. 825–841. DUNAGAN, S.P., 1998a, Lacustrine and palustrine carbonates from the Morrison Formation (Upper Jurassic), east-central Colorado, U.S.A.: implications for depositional patterns, paleoecology, paleohydrology, and paleoclimatology [unpublished Ph.D. thesis]: Knoxville, Tennessee, University of Tennessee, 276 p. DUNAGAN, S.P., 1998b, Constraining Late Jurassic paleoclimate within the Morrison paleoecosystem, east of the Ancestral Rockies: insights from the terrestrial carbonate record (abstract): Fifth International Symposium on the Jurassic System, Abstracts and Program, p. 24. DUNAGAN, S.P., DEMKO, T.M., DRIESE, S.G., AND WALKER, K.R., 1996, Lacustrine and palustrine carbonate facies of the Morrison Formation (Upper Jurassic): implications for paleoenvironmental reconstructions (abstract): Geological Society of America, Abstracts with Programs, v. 28, p. 336. FAILL, R.T., 1985, The Acadian orogeny and the Catskill Delta, in Woodrow, D.L., and Sevon, W.D., eds., The Catskill Delta: Geological Society of America, Special Paper 201, p. 15– 37. FLOQUET, M., SALOMON, J., AND VADOT, J.-P., 1994, Uppermost Cretaceous and Paleogene fluviolacustrine basins in the northern Iberian Ranges (Spain), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 223–227. FREYTET, P., 1973, Petrography and paleo-environment of continental carbonate deposits with particular reference to the Upper Cretaceous and Lower Eocene of the Languedoc (southern France): Sedimentary Geology, v. 10, p. 25–60. FREYTET, P, AND PLAZIAT, J.-C., 1982, Continental Carbonate Sedimentation and Pedogenesis— Late Cretaceous and Early Tertiary of Southern France: Stuttgart, Germany, E. Schweizerbart’sche Verlagsbuchhandlung (Na¨gele u. Obermiller), Contributions to Sedimentology No. 12, 213 p. FRIEND, P.F., AND MOODY-STUART, M., 1970, Carbonate deposition on the river floodplains of the Wood Bay Formation (Devonian) of Spitsbergen: Geological Magazine, v. 107, p. 181– 195. GIERLOWSKI-KORDESCH, E., AND KELTS, K., 1994, Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, 427 p. GINSBURG, R.N., HARDIE, L.A., BRICKER, O.P, GARRETT, P., AND WANLESS, H.R., 1977, Exposure index: a quantitative approach to defining position within the tidal zone, in Hardie, L.A., ed., Sedimentation on the Modern Carbonate Tidal Flats of Northwest Andros Island, Bahamas: Baltimore, Johns Hopkins University Press, p. 7–11. GORDON, E.A., AND BRIDGE, J.S., 1987, Evolution of Catskill (Upper Devonian) river systems: intra- and extrabasinal controls: Journal of Sedimentary Petrology, v. 57, p. 234–249. JOHNSON, K.G., AND FRIEDMAN, G.M., 1969, The Tully clastic correlatives (Upper Devonian) of New York State: a model for recognition of alluvial, dune(?), tidal, nearshore (bar and lagoon), and offshore sedimentary environments in a tectonic delta complex: Journal of Sedimentary Petrology, v. 39, p. 451–485. KELTS, K., AND HSU¨, K.J., 1978, Freshwater carbonate sedimentation, in Lerman, A., ed., Lakes: Chemistry, Geology, and Physics: New York, Springer-Verlag, p. 295–323. KENT, D.V., 1985, Paleocontinental setting for the Catskill Delta, in Woodrow, D.L., and Sevon, W.D., eds., The Catskill Delta: Geological Society of America, Special Paper 201, p. 9–13. MACHEL, H.G., AND BURTON, E.A., 1991, Factors governing cathodoluminescence in calcite and dolomite, and their implications for studies of carbonate diagenesis, in Barker, C.E., and Kopp, O.C., eds., Luminescence Microscopy: Quantitative and Qualitative Aspects: SEPM, Short Course 25, p. 9–25. MCKENZIE, J.A., 1985, Carbon isotopes and productivity in the lacustrine and marine environment, in Stumm, W., ed., Chemical Processes in Lakes: New York, Wiley, p. 99–118. MEDIAVILLA, R., MART´ıN-SERRANO, A., DABRIO, C.J., AND SANTISTEBAN, J.I., 1994, Cenozoic lacustrine deposits in the Duero Basin (Spain), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 53–59. MELEŃDEZ, N., MELEŃDEZ, A., AND GO´MEZ FERNAŃDEZ, J.C., 1994, La Serranıá de Cuenca Basin (Lower Cretaceous), Iberian Ranges, central Spain, in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 215–219. MORA, C.I., AND DRIESE, S.G., in press, Palaeoclimatic significance and stable carbon isotopes of Palaeozoic red bed paleosols, Appalachian Basin, USA and Canada, in Thiry, M., and Simon-Coinçon, R., eds., Palaeoweathering, Palaeosurfaces and Related Continental Deposits: International Association of Sedimentologists, Special Publication. MORA, C.I., DRIESE, S.G., AND COLARUSSO, L.A., 1996, Middle to Late Paleozoic atmospheric CO2 from soil carbonate and organic matter: Science, v. 271, p. 1105–1107. MORA, C.I., FASTOVSKY, D.E., AND DRIESE, S.G., 1993, Geochemistry and Stable Isotopes of Paleosols: A short-course manual for the Annual Meeting of the Geological Society of America Convention: University of Tennessee, Department of Geological Sciences, Studies in Geology No. 23, 65 p. MORA, C.I., SHELDON, B.T., ELLIOTT, W.C., AND DRIESE, S.G., 1998, An oxygen isotope study of illite and calcite in three Appalachian Paleozoic vertic paleosols: Journal of Sedimentary Research, v. 68, p. 456–464. PARNELL, J., ROGERS, D., ASTIN, T., AND MARSHALL, J., 1994, Devonian Orcadian Basin, northern

LATE DEVONIAN PALUSTRINE CARBONATES Scotland, UK, in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 73–79. PFEFFERKORN, H.W., AND FUCHS, K., 1991, A field classification of fossil plant substrate interactions: Neues Jahrbuch fu¨r Geologie und Palaöntologie, Abhandlungen, v. 183, p. 17–36. PLATT, N.H., 1989, Continental sedimentation in an evolving rift basin: the Lower Cretaceous of the western Cameros Basin (northern Spain): Sedimentology, v. 64, p. 91–109. PLATT, N.H., 1992, Freshwater-carbonates from the Lower Freshwater Molasse (Oligocene, western Switzerland): sedimentology and stable isotopes: Sedimentary Geology, v. 78, p. 81–99. PLATT, N.H., 1994, The western Cameros Basin, northern Spain: Rupelo Formation (Berriasian), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 195–202. PLATT, N.H., AND WRIGHT, V.P., 1991, Lacustrine carbonates: facies models, facies distribution, and hydrocarbon aspects, in Anadoń, P., Cabrera, Ll., and Kelts, K., Lacustrine Facies Analysis: International Association of Sedimentologists, Special Publication 13, p. 57–74. PLATT, N.H., AND WRIGHT, V.P., 1992, Palustrine carbonates and the Florida Everglades: toward an exposure index for the fresh-water environment: Journal of Sedimentary Petrology, v. 62, p. 1058–1071. POPP, B.N., ANDERSON, T.F., AND SANDBERG, P.A., 1986, Brachiopods as indicators of original isotopic compositions in some Paleozoic limestones: Geological Society of America, Bulletin, v. 97, p. 1262–1269. RETALLACK, G.J., 1988, Field recognition of paleosols, in Reinhardt, J., and Sigleo, W.R., eds., Paleosols and Weathering through Geologic Time: Geological Society of America, Special Paper 216, p. 1–20. RETALLACK, G.J., 1990, Soils of the Past: Boston, Unwin-Hyman, 520 p. SARJEANT, W.A.S., 1975, Plant trace fossils, in Frey, R.W., ed., The Study of Trace Fossils: New York, Springer-Verlag, p. 163–179. SCHA¨FER, A., AND SNEH, A., 1983, Lower Rotliegend fluvio-lacustrine sequences of the SaarNahe Basin: Geologische Rundschau, v. 72, p. 1135–1145. SOUTHGATE, P.N., 1994, A Cambrian alkaline playa from the Officer Basin, South Australia, in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 67–71. SOUTHGATE, P.N., LAMBERT, I.B., DONNELLY, T.H., HENRY, R., ETMINAN, H., AND WESTE, G., 1989, Depositional environments and diagenesis in Lake Parakeelya: a Cambrian alkaline playa from the Officer Basin, South Australia: Sedimentology, v. 33, p. 1091–1112. STANLEY, K.O., AND COLLINSON, J.W., 1979, Depositional history of Paleocene–Lower Eocene Flagstaff Limestone and coeval rocks, central Utah: American Association of Petroleum Geologists, Bulletin, v. 63, p. 311–323. STAPF, K.R.F., 1989, Biogene fluvio-lakustrine Sedimentation im Rotliegend des permokarbonen Saar-Nahe-Beckens (SW-Deutschland): Facies, v. 20, p. 169–198. TALBOT, M.R., 1990, A review of the paleohydrological interpretation of carbon and oxygen isotopic ratios in primary lacustrine carbonates: Chemical Geology, v. 80, p. 261–279. TALBOT, M.R., AND KELTS, K., 1990, Paleolimnological signatures from Carbon and Oxygen isotopic ratios in carbonates from organic carbon-rich lacustrine sediments, in Katz, B.J., ed., Lacustrine Basin Exploration—Case Studies and Modern Analogs: Tulsa, Oklahoma, American Association of Petroleum Geologists, p. 99–112. TOUTIN-MORIN, N., 1994, Lacustrine and palustrine carbonates in the Permian of eastern Provence (France), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 91–96. TUCKER, M.E., AND WRIGHT, V.P., 1990, Carbonate Sedimentology: Oxford, U.K., Blackwell, 482 p. VALERO GARCE´S, B.L., 1994a, The Permian lacustrine Basque Basin (western Pyrenees): an example for high environmental variability in small and shallow carbonate lakes developed in closed systems, in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 101–106. VALERO GARCE´S, B.L., 1994b, Carbonate lacustrine episodes in the continental Permian Aragoń–

783

Beárn Basin (western Pyrenees), in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 107–119. VALERO GARCE´S, B.L., AND GIERLOWSKI-KORDESCH, E., 1994, Lacustrine carbonate deposition in Middle Pennsylvanian cyclothems—the Upper Freeport Formation, Appalachian Basin, USA: Journal of Paleolimnology, v. 11, p. 109–132. VALERO GARCE´S, B.L., GIERLOWSKI-KORDESCH, E., AND BRAGONIER, W.A., 1994, Lacustrine facies model for non-marine limestone within cyclothems in the Pennsylvanian (Upper Freeport Formation, Appalachian Basin) and its implications, in Lomando, A.J., Schreiber, B.C., and Harris, P.M., eds., Lacustrine Reservoirs and Depositional Systems: SEPM, Core Workshop 19, p. 321–381. VALERO GARCE´S, B.L., GIERLOWSKI-KORDESCH, E., AND BRAGONIER, W.A., 1997, Pennsylvanian continental cyclothem development: no evidence of direct climatic control in the Upper Freeport Formation (Allegheny Group) of Pennsylvania (northern Appalachian Basin): Sedimentary Geology, v. 109, p. 305–319. WEEDMAN, S.D., 1994, Upper Allegheny Group (Middle Pennsylvanian lacustrine limestones of the Appalachian Basin, USA, in Gierlowski-Kordesch, E., and Kelts, K., eds., Global Geological Record of Lake Basins, Volume 1: Cambridge, U.K., Cambridge University Press, p. 127–134. WELLS, N.A., 1983, Carbonate deposition, physical limnology, and environmentally controlled chert formation in Paleocene–Eocene Lake Flagstaff, Central Utah: Sedimentary Geology, v. 35, p. 263–296. WHITE, A.H., AND YOUNGS, B.C., 1980, Cambrian alkali playa-lacustrine sequences in the northeastern Officer Basin, South Australia: Journal of Sedimentary Petrology, v. 50, p. 1279– 1286. WOODROW, D.L., 1985, Paleogeography, paleoclimate, and sedimentary processes of the Late Devonian Catskill Delta, in Woodrow, D.L., and Sevon, W.D., eds., The Catskill Delta: Geological Society of America, Special Paper 201, p. 51–63. WRIGHT, V.P., AND PLATT, N.H., 1995, Seasonal wetland carbonate sequences and dynamic catenas: a re-appraisal of palustrine limestones: Sedimentary Geology, v. 99, p. 65–71. WRIGHT, V.P., PLATT, N.H., AND WIMBLEDON, W.A., 1988, Biogenic laminar calcretes: evidence of calcified root-mat horizons in paleosols: Sedimentology, v. 35, p. 603–620. Received 26 January 1998; accepted 26 June 1998. APPENDIX

Locations of Outcrop Sections Davenport Center (DC).—Abandoned quarry exposures; from New York Highway 23, proceed 0.8 km southwest of town of Davenport Center, to private gravel road on the south side of Highway 23; proceed 0.5 km on gravel road to quarry highwall (primary section of Demicco et al. 1987). Map coordinates: 428 269 150 N, 748 559 300 W; West Davenport, NY, 7.59 topographic quadrangle map. Schoharie Creek (SC).—Natural stream-bluff exposures; from New York Highway 30, proceed to paved road that parallels west side of Schoharie Creek, to 0.8 km due north of town of Gilboa; park on paved road and hike 150 m east, then wade across Schoharie Creek to 10–20 m high bluffs located on east bank of creek (Schoharie Creek section of Bridge and Willis 1994). Map coordinates: 428 239 450 N, 748 279 050 W, Gilboa, NY 7.59 topographic quadrangle map. Manorkill Falls (MK).—Natural outcrops at the base of Manorkill Falls along Manorkill Creek, where it empties into the east side of the Schoharie Reservoir, 2.4 km south of the town of Gilboa, NY; park on a paved road 50 m south of the bridge over the falls and proceed down a footpath to the falls. Map coordinates: 428 229 480 N, 748 259 550 W, Gilboa, NY 7.59 topographic quadrangle map.