Studies of the physical stratigraphy and analyses of the Middle Pennsylvanian flora and fauna of some coal beds and marine units of the Breathitt Formation in Kentucky, the Pottsville and Allegheny Formations in Ohio, and the Kanawha Formation and Charleston Sandstone in West Virginia show a need for the revision of stratigraphic nomenclature of the Pottsville Formation and the lower part of the Allegheny Formation and equivalent strata. Attempts to project single stratigraphic elements from one region to another have resulted historically in multiple miscorrelations. A major marine unit (previously misidentifled as the Vanport limestone of the Breathitt and Allegheny Formations) is here named the Obryan Member of the Breathitt Formation in northeastern Kentucky and of the Allegheny Formation in southern Ohio. The Obryan is characterized by the fusulinid Beedeina ashlandensis Douglass and is correlated with the Columbiana Member of the Allegheny Formation in central Ohio, which also contains that fusulinid. This correlation and the correlation of the Boggs Limestone Member of the Pottsville Formation in Ohio with the Stoney Fork Member of the Breathitt Formation in Kentucky are supported by analyses of Middle Pennsylvanian conodonts. A preliminary zonation of conodonts for strata of the Pottsville and Allegheny Formations shows that the major marine units of these formations in Ohio are biostratigraphically distinct. The Obryan Member is locally absent, but its position is marked by overlying clay beds in many parts of Kentucky, Ohio, and West Virginia. The Vanport Limestone Member of the Allegheny Formation (as identified in Pennsylvania and central Ohio) is here correlated with the Zaleski Flint Member (Allegheny Formation) in southern Ohio. The Kilgore Flint Member (new name, Breathitt Formation), the informal Limekiln limestone and informal Flint Ridge flint (Breathitt Formation) in Kentucky, and the informal Kanawha black flint (Kanawha Formation) in West Virginia are correlated with the Putnam Hill Limestone Member (Allegheny Formation) in Ohio. These latter chert deposits are shoreward (southward and southeastward) facies of a marine unit deposited mostly in restricted estuaries and bays. The chert deposits appear to result from a widespread episode of silicification of fossiliferous marine siltstones and limestones that locally affected underlying peats and silts. The Kilgore and Obryan Members and their equivalents are used as the two principal stratigraphic marker beds for analyses of Middle Pennsylvanian sections extending across northeastern Kentucky from central Ohio to central West Virginia. Clay units and coal beds that overlie the Obryan Member contain flint clay beds (tonsteins) that are, in part, the product of volcanic ash falls. The range zones of selected palynomorphs from northeastern Kentucky and southeastern Ohio corroborate some of the correlations proposed herein.

Core drilling in poorly exposed Lower and Middle Pennsylvanian strata of the Pottsville and Allegheny Groups in northeastern Ohio has led to a better understanding of the character and distribution of key Pennsylvanian marine units. Two unknown and three previously known marine and marine-influenced units are identified in strata of this area in the Pottsville Group. Distribution and facies maps of these marine units in northeastern Ohio suggest pre-Pennsylvanian erosional paleotopography and periodic movement on subsurface faults locally influenced depositional patterns. Additionally, the traditional placements of the Lowellville marine unit and the Quakertown coal in the stratigraphic column for Ohio appear to be in error. The new data suggest the need for an extensive revision of the geologic column for the Lower and Middle Pennsylvanian rocks in Ohio and the need to develop a more representative stratigraphic nomenclature and framework for these rocks. Core drilling referenced in this investigation was done as part of the recent statewide mapping and core-drilling program conducted by the Ohio Geological Survey.

The stratigraphy of the Kanawha Formation in West Virginia has been confused by regional miscorrelations of many units. To resolve these inconsistencies, this report has: (1) revised and defined three widely distributed marine units as the Betsie, Dingess, and Winifrede Shale Members of the Kanawha Formation (Middle Pennsylvanian); (2) extended the name “Fire Clay” into West Virginia from Kentucky for a coal bed regionally identified by its flint clay (tonstein) parting and miscorrelated in different areas of West Virginia as the older Hernshaw coal bed or the younger Chilton coal bed; and (3) reestablished the stratigraphic positions of several key coal beds that have been regionally miscorrelated from their type areas. A stratigraphic section parallel to depositional strike, from the Kanawha River Valley in central West Virginia to the Tug Fork of the Big Sandy River in southwestern West Virginia, shows the correlation and continuity of marine members and coal beds of the middle part of the Kanawha Formation.

Selected Middle Pennsylvanian coals and one Upper Pennsylvanian coal from three outcrop sections and one exploratory drillcore in the central and northern Appalachian basin were analyzed for their spore content. In the studied assemblages, the most frequently encountered taxa were species of Lycospora, Laevigatosporites, Punctatisporites, Densosporites (and related crassicinulate genera), Granulatisporites (and related sphaerotriangular genera), and Florinites . Mid-Middle Pennsylvanian assemblages are generally dominated by Lycospora , with L. pellucida , L. pusilla , L. granulata , L. orbicula , and L. micropapillata being the most common species. A few beds in this interval, however, show more even distributions of Lycospora (produced by arboreous lycopsids) and forms related to tree ferns, calamites, and cordaites. In general, a stratigraphic upward increase in tree fern taxa is observed, with upper Middle Pennsylvanian coals being codominated or dominated by tree fern spores. In addition, the range zones of the following taxa appear to be useful for palynologic delineation of Middle Pennsylvanian strata on both intra- and interbasinal scales: Microreticulatisporites sulcatus, Triquitrites sculptilis, Laevigatosporites globosus, Radiizonates difformis-rotatus, Torispora securis, Thymospora pseudothiessenii, Murospora kosankei, Mooreisporites inusitatus, Granasporites medius, Schulzospora, Densosporites, Schopfites, Lycospora, Cirratriradites , and Vestispora . The recognition of these taxa in Appalachian spore assemblages allows for comparison and correlation of Pennsylvanian strata in the Eastern and Western Interior basins of North America and the Upper Carboniferous of Western Europe.

At least 10 marine-influenced stratigraphic intervals have been distinguished in the Kanawha Formation. Marine units range from 3 to 34 m in thickness and have been divided into component sedimentary facies based on lithology, body and trace fossils, sedimentary structures, paleocurrents, and geometry. Offshore facies consist of dark gray laminated shales, whereas nearshore and littoral deposits are typified by interlaminated to thinly interbedded very fine sandstone, siltstone, and shale. Current ripple bedding (flaser, wavy, lenticular) and ripple cross-lamination are widely developed. Tidal influence was significant and is reflected by rhythmic textures and structures and bipolar paleocurrents. Phosphatic brachiopods and burrowing bivalves predominate in nearshore and littoral facies, while calcareous brachiopods dominate offshore facies and are often accompanied by bivalves, bryozoans, echinoderms, cephalopods, and corals. Primary faunal distribution was likely to have been controlled mainly by substrate, salinity, and dissolved oxygen. Two trace fossil assemblages are common. The Olivellites assemblage has a high diversity and is represented by both infaunal burrows and surface tracks and trails developed in the nearshore zone and low- to midtidal flats. The Phycodes-Zoophycos assemblage is a low-diversity assemblage of infaunal deposit feeders formed in upper tidal flats, restricted bays, and tidal creeks. Lowstands of sea level caused incisement of fluvial channels, whereas rising sea level led to expansion of tidal plains and estuaries. Shoreface retreat produced ravinement surfaces and transgressive lags that now separate coastal plain and marginal marine facies from shallow subtidal facies. Coastal progradation began during highstands after estuarine sediment sinks had filled and may have intensified during falling sea level.

The Middle Pennsylvanian Fire Clay tonstein, mostly kaolinite and minor accessory minerals, is an altered and lithified volcanic ash preserved as a thin, isochronous layer associated with the Fire Clay coal bed. Seven samples of the tonstein, taken along a 300-km traverse of the central Appalachian basin, contain cogenetic phenocrysts and trapped silicate-melt inclusions of a rhyolitic magma. The phenocrysts include beta-form quartz, apatite, zircon, sanidine, pyroxene, amphibole, monazite, garnet, biotite, and various sulfides. An inherited component of the zircons (determined from U-Pb isotope analyses) provides evidence that the source of the Fire Clay ash was Middle Proterozoic (Grenvillian) continental crust inboard of the active North American margin. 40 Ar/ 39 Ar plateau ages of seven sanidine samples from the tonstein have a mean age of 310.9 ± 0.8 Ma, which suggests that it is the product of a single, large-volume, high-silica, rhyolitic eruption possibly associated with one of the Hercynian granitic plutons in the Piedmont. Biostratigraphic analyses correlate the Fire Clay coal bed with a position just below the top of the Trace Creek Member of the Atoka Formation in the North American Midcontinent and near the Westphalian B-C boundary in western Europe.

40 Ar/ 39 Ar plateau age spectra of seven sanidine samples from the Fire Clay tonstein (Middle Pennsylvanian), collected along a 300-km traverse in the Appalachian basin, range from 310.3 to 311.4 Ma. All plateau ages agree, within the limits of analytical precision, with their respective total gas ages. This agreement, together with the reproducibility between samples, suggests the analyzed samples did not contain any significant contaminant feldspar. The mean of these seven plateau ages, 310.9 ± 0.8 Ma, is interpreted to represent a precise numerical estimate of time of eruption and deposition of this tonstein and the coal bed in which it is found. The lack of any discernible difference between the age of two samples of the Fire Clay tonstein collected from east of the Pine Mountain thrust fault, along with the age of five samples from west of this fault, suggests that the Fire Clay tonstein has been reliably correlated with a tonstein on the Cumberland overthrust sheet. This correlation, together with the age data presented in this paper, indicates that the Pine Mountain thrust fault must be younger than the 310.9-Ma age obtained for the Fire Clay tonstein. The Fire Clay tonstein is biostratigraphically correlated with the Trace Creek Shale Member of the Atoka Formation in the Midcontinent of North America and with a position near the Westphalian B-C boundary in Western Europe. Our age of 310.9 ± 0.8 Ma for the Westphalian B-C boundary represents a well-constrained point, useful for the numerical refinement of the geologic time scale.

An erosional hiatus over almost the entire area between Pennsylvania and western New Brunswick suggests that the region was mountainous from the Middle Devonian Acadian orogeny through Pennsylvanian time. Of seven basins or deposits of southeast-era New England, the ages of three (Narragansett, Norfolk, and Worcester) are florally determined as Westphalian B (Middle Pennsylvanian) to Stephanian B or C (Late Pennsylvanian); three lack flora but are of inferred Carboniferous age (North Scituate, Woonsocket, and Pin Hill), and one is of possibly Carboniferous age (Sturbridge). The first three are characterized by flora suggesting a tropical or subtropical climate and by alluvial fan facies deposited in an intermontane basin. Four of these basins or deposits lie in the Avalon Terrane, three just west of the Nashoba Terrane, but none has been recognized in the intermediate Nashoba Terrane. These basin deposits can be correlated with similar deposits in Atlantic Canada. Tectonic effects of the Alleghanian orogeny are many and diverse, resulting in important tectonic controls on the formation and evolution of the coal basins. Grabens surrounded by uplands were formed by extension or strike-slip fault-related extension and were filled with Carboniferous sediments during the earliest Alleghanian orogenic episode. These sediments along with the basement complex, were multiply deformed during Permo-Carboniferous Alleghanian orogenic episodes, which involved folding, thrust faulting, plutonism, regional metamorphism, and strike-slip faulting. Metamorphism throughout the outcrop areas ranges from anchizone to K-spar zone in the Narragansett Basin; anchizone to possibly lower greenschist in the Norfolk Basin; and below the almandine zone in the “Worcester Coal Mine” deposit. Important effects of the tectonism are the widespread anthracitization and tectonic thickening of the low-sulfur and high-ash coals.

The Pennsylvania Anthracite region contains numerous thick, extensive, low-sulfur coal beds of Pennsylvanian age. These coal beds are the result of the accumulation of swamp vegetation, and deposition of fine- to coarse-grained clastics in a terrestrial, rapidly sinking asymmetric basin, whose source area lay to the southeast of the Anthracite region. The beds in this basin were extensively folded and faulted in Permian-Triassic time as the strata above a basal décollement were thrust northwestward.

Clastic sediments in the Pocahontas Formation of the east-central Appalachian basin in Virginia and West Virginia were deposited in a series of stacked delta lobes along the southeastern shoreline of a Carboniferous Appalachian seaway. These sediments prograded northwestward and were depositionally continuous with precursor Mississippian coal-bearing strata presently located primarily to the southeast in the faulted and folded belt of the Appalachians. During periodic stillstands in Early Pennsylvanian time, coastal currents and waves reworked and segregated sand along the delta front, forming a system of curvilinear barrier-bars. Behind these protective barriers, vegetation flourished in swamps on the abandoned delta lobes. An analysis of the relationship of coal occurrences to the geometries of sandstone units indicates that the origin of thick, low-sulfur coal in the Pocahontas Formation can be attributed to the initial and continuing accumulation of peat on the periodically inactive delta lobes. Conversely thin, impure, and discontinuous peat (coal) accumulated in the shale-dominated interlobe areas. An increase in the sulfur content of the coal to the northwest may have resulted from the proximity of marine conditions to the distal ends of the delta lobes. The genetic relation of coal distribution and sulfur content to the delta system provides a basis for designing exploration programs in coal-bearing strata of the Appalachian basin, particularly for predicting both the quantity and the quality of the coal.