Abstract Immediately prior to the opening of the Atlantic Ocean in the Mesozoic Era, numerous extensional and transtensional basins developed along the eastern margin of North America from Florida to Canada and from the Appalachian Piedmont eastward to the edge of the present-day continental shelf. Using a petroleum system-based methodology, the U.S. Geological Survey examined 13 onshore Mesozoic synrift basins and estimated a mean undiscovered natural gas resource of 3.86 trillion cubic feet (TCF; 109 billion cubic meters, BCM) of gas and a mean undiscovered natural gas liquids resource of 135 million barrels (MMBNGL; 21.5 million cubic meters, MMCM) in continuous accumulations within five of these basins: the Deep River, Dan River-Danville, Richmond, Taylorsville basins, and the southern part of the Newark Basin. The other eight basins were examined, but not assessed due to insufficient data. An additional 26 basins in the East Coast Mesozoic synrift basins trend were examined here for further insights into the development and evolution of a large, but short-lived set of petroleum systems in Mesozoic synrift basins. An individual composite total petroleum system is contained within each of the assessed basins. Small amounts of oil and natural gas have been recovered from many of the basins, yet no commercial production has been established. Potential and identified source rocks are present as shale and (or) coal. Potential reservoir rocks are low porosity and permeability sandstones as well as shale, siltstone, coal, and fractured igneous rocks. Examination of data indicates that many of these rift basins have undergone substantial uplift (greater than 4,000 ft, 1200 m), and one or more episodes of water washing have affected oil accumulations. Drilling for conventionally trapped structural and (or) stratigraphic prospects has not been successful. Remaining potential appears to be in continuous (unconventional) gas and natural gas liquid accumulations in a variety of reservoir types.

Abstract The Richmond basin, a rift basin of Late Triassic to Early Jurassic age in east-central Virginia, produced the first coal mined in the United States in the early 1700s. These Triassic coal beds are thick and gas-rich, and fatal explosions were common during the early history of exploitation. Since 1897, at least 38 confirmed oil, natural gas, and coal tests have been drilled within the basin. Although shows of asphaltic petroleum and natural gas indicate that active petroleum systems existed therein, no economic hydrocarbon accumulations have been discovered to-date. The Richmond basin has been assessed by the U. S. Geological Survey (USGS) as one composite total petroleum system, in which the hydrocarbon potential of the source beds (both coal and dark shale) and potential reservoirs have been combined into a single continuous tight gas assessment unit within the Chesterfield and Tuckahoe groups (Upper Triassic). Sandstone porosities are generally low (<1 % to 14 %). Thick, dark-colored shales have total organic carbon (TOC) values that range from <1% to 10%, and vitrinite reflectance (%R O ) values that range generally from about 0.3 to 1.1%, which indicates that the submature to super mature shales appear to be the source of the hydrocarbons recovered from some of the boreholes. The stratigraphic combination of these potential source rocks, tight sandstones, and hydrocarbon shows are the basis for the current USGS assessment of the technically recoverable undiscovered hydrocarbon resources of the basin. Mean values for these resources are 211 billion cubic feet of gas (BCFG) and 11 million barrels of natural gas liquids (MMBNGL).

Abstract The Taylorsville basin is a rift basin of Late Triassic to Early Jurassic age in east-central Virginia and adjacent Maryland. The basin has been a target for oil and gas exploration by Texaco and partners in the 1980s, when six continuous cores were drilled followed by three deeper exploratory wells. Currently, no hydrocarbon production has been established from the basin. Relatively thick sequences of dark-colored shale that may serve both as source rocks and self-sourced reservoirs for hydrocarbons have been encountered near the basin’s center. The current USGS assessment concludes that the mean values for undiscovered hydrocarbons in the basin are 1,064 billion cubic feet of gas (BCFG) and 37 million barrels of natural gas liquids (MMBNGL). The Taylorsville basin contains one composite total petroleum system, in which the hydrocarbon potential of the source beds and potential reservoirs were combined and assessed together as a single continuous gas assessment unit. Potential source rocks within the Taylorsville basin include coals and shales of the Triassic Falling Creek and Port Royal formations. Vitrinite reflectance data indicate that the source rocks range from pre-peak oil to peak gas thermal maturity. Potential reservoir rocks are continuous accumulations in shales, coal beds, and tight sandstones as well as possible conventional accumulations in porous and permeable strata within the Triassic Dowell and King George groups. However, well log based sandstone porosity values are generally low. Potential seals may be present in shale beds or igneous intrusions within the basin or by pore-throat restrictions within the continuous reservoir bodies.

Abstract The linear Sequatchie anticline interrupts the continuity of the Appalachian Cumberland Plateau from east-Central Tennessee southward into Alabama to near the latitude of Birmingham. The anticline was breached by erosion during the late Tertiary, thereby producing Sequatchie Valley and revealing the details of its geologic structure—the anticline is thrust faulted on its northwest flank, and that thrust is now known to be part of a tectonic ramp that extends upward from the Lower Cambrian Rome Formation to flatten to the northwest into a higher detachment within the weak shale and coal beds in the Pennsylvanian deltaic sedimentary rocks. The same thrust emerges to the northwest as the Cumberland Plateau overthrust, and appears to be a mirror-image analog of the Pine Mountain fault located in the Plateau to the northeast. The purpose of this one-day field trip is to (1) provide an introduction to the Sequatchie Valley structure and the Mississippian-Pennsylvanian strata that form the crest and limbs of the anticline, and (2) gain some insight into the evolution of the topography in the southern Cumberland Plateau as the valley was exhumed during the late Tertiary. The first field trip stop is along Tennessee State Route (SR) 8 northwest of Dunlap to examine well-exposed rocks and structures along the upper detachment where it propagates along coal and shale beds in the Pennsylvanian section. The second field trip stop is up the southeast flank of the anticline along Tennessee SR-111 east of Dunlap to review the nearly continuous exposure of the Paleozoic section from the Devonian-Mississippian Chattanooga Shale to the top of the Mississippian.

Abstract Shale gas is produced from the Woodford, Caney, and Fayetteville shales (Devonian and/or Mississippian), and coal-bed gas is produced from the Hartshorne and McAlester coal beds in the Arkoma basin of Oklahoma and Arkansas. The U.S. Geological Survey is currently assessing the technically recoverable hydrocarbon resources of the Arkoma basin and for assessment purposes has divided the continuous shale gas (unconventional) resources into three total petroleum systems together with their associated assessment units (AUs). Each of the gas shale AUs contains 2.5 % or more total organic carbon, is thermally mature with respect to gas generation over much of its area within the basin, and may be accessed by the drill at depths less than 14,000 feet. In addition, the Woodford, Caney, and Fayetteville Shale Gas AUs underlie relatively large areas that have not been tested adequately by the drill. Coal-bed gas is currently being produced from the Hartshorne and McAlester coal beds in the Arkoma basin, and for assessment purposes they have been grouped together into one total petroleum system and one AU. Much of the area where the coal beds are relatively shallow in the northern part of the AU has been drilled. However, the area underlain by coal in the southern part of the basin, which is deeper and more structurally deformed, remains largely unexplored for coalbed methane.

The coal systems concept may be used to organize the geologic data for a relatively large, complex area, such as the Appalachian basin, in order to facilitate coal assessments in the area. The concept is especially valuable in subjective assessments of future coal production, which would require a detailed understanding of the coal geology and coal chemistry of the region. In addition, subjective assessments of future coal production would be enhanced by a geographical information system that contains the geologic and geochemical data commonly prepared for conventional coal assessments. Coal systems are generally defined as one or more coal beds or groups of coal beds that have had the same or similar genetic history from their inception as peat deposits, through their burial, diagenesis, and epigenesis to their ultimate preservation as lignite, bituminous coal, or anthracite. The central and northern parts of the Appalachian basin contain seven coal systems (Coal Systems A–G). These systems may be defined generally on the following criteria: (1) on the primary characteristics of their paleopeat deposits, (2) on the stratigraphic framework of the Paleozoic coal measures, (3) on the relative abundance of coal beds within the major stratigraphic groupings, (4) on the amount of sulfur related to the geologic and climatic conditions under which paleopeat deposits accumulated, and (5) on the rank of the coal (lignite to anthracite).

Abstract The E5 transect extends southeastward from the Cumberland Plateau across the Appalachian orogen, the Atlantic Coastal Plain, Continental Shelf and Slope, and the Blake Plateau Basin; it is a transect through the Precambrian-early Paleozoic and Mesozoic-Tertiary continental margins of North America. The transect consists primarily of a 100-km-wide geologic strip map, a cross section, and supporting geophysical data. The cross section is based on surface geology, surface and subsurface data from Coastal Plain and offshore drill holes, shipboard and aeromagnetic data, and gravity and seismic reflection data, including the ADCOH and COCORP southern Appalachians lines. Elements of the map and cross section include: (1) the Appalachian foreland fold-thrust belt and western Blue Ridge Late Proterozoic-Paleozoic continental margin; (2) the eastern Blue Ridge-Chauga belt-Inner Piedmont oceanic-continental fragment terrane; (3) the volcanicplutonic Carolina terrane containing the middle to late Paleozoic high-grade Kiokee belt; and (4) a major geophysical ly defined terrane beneath the Coastal Plain. Three Paleozoic sutures may be present along the section line: the Hayesville thrust, the Inner Piedmont-Carolina terrane boundary (Taconic or Acadian suture?), and an eastern boundary of the Carolina terrane (Alleghanian? suture) in the subsurface beneath the Coastal Plain. The modern continental margin consists of the terrestrial clastics-filled Triassic-Jurassic basins and offshore marine Jurassic- Cretaceous clastic-carbonate bank succession overlain by younger Cretaceous and Tertiary sediments. Above the Late Cretaceous onshore unconformity lie Cenozoic sediments that represent seaward prograding of the shelf-slope, truncated by Miocene to recent wave abrasion and currents.

Abstract DNAG Transect E-5. Part of GSA's DNAG Continent-Ocean Transect Series, this transect contains all or most of the following: free-air gravity and magnetic anomaly profiles, heat flow measurements, geologic cross section with no vertical exaggeration, multi-channel seismic reflection profiles, tectonic kindred cross section with vertical exaggeration, geologic map, stratigraphic diagram, and an index map. All transects are on a scale of 1:500,000.

Abstract The Appalachian basin is a broad, elongate synclinorium that extends from the southern shore of Lake Ontario in New York generally southwestward about 1,500 km to the Gulf Coastal Plain in Alabama. It has a surface area of more than 500,000 km2 and is filled by about 1,800,000 km 3 of Paleozoic rocks ranging in age from Early Cambrian to Early Permian. The western edge of the basin is at the crest of the Cincinnati arch (Fig. 1 A). Paleozoic strata dip gently eastward from the arch, first beneath the Appalachian Plateaus and then into and beneath the complexly folded and faulted Valley and Ridge. Except where they were thrust westward along the flanks of the Blue Ridge during the Alleghanian Orogeny, easternmost Paleozoic strata of the basin lie concealed beneath Blue Ridge and Piedmont thrust sheets. The Appalachian basin contains two conspicuous, smaller basins: the Dunkard in southwestern Pennsylvania and contiguous West Virginia and Ohio, and the Black Warrior in Alabama and Mississippi (Plate 6H). The Dunkard basin lies above the Rome trough, suggesting that it may be in part inherited from that early Paleozoic feature. The Dunkard basin is a shallow synclinal trough elongated parallel to the regional strike of the Appalachians. In contrast, the Black Warrior basin is a homocline that dips generally southwestwardly from the Nashville dome (Thomas, 1988) at a high angle to the strike of the Valley and Ridge Paleozoic rocks.

Abstract The Appalachian basin is an elongate asymmetric synclinorium that extends from Lake Ontario southwestwardfor 1600 km through New York, Pennsylvania, Ohio, WestVirginia, Virginia, eastern Kentucky, Tennessee, and Georgia to Alabama (Fig. 1). The basin consists of Paleozoic strata ranging from 600 to 900 m thick on its west flank, along the Cincinnati arch, to more than 13,700 m thick on its east side in central Pennsylvania adjacent to an allochthonous metamorphic terrain. As defined herein, the basin-filling rocks underlie most of the central and southern parts of the Appalachian mountain chain. To the northeast in New England, coal-bearing strata of Pennsylvanian age underlie approximately370 sq km in the Narragansett Basin.

Abstract The central and part of the southern Appalachian Valley and Ridge and Plateau are underlain by an elongate basin that extends from the Great Lakes southwestward to a low broad arch that lies along the southern Tennessee border (Fig. 1). This arch, a branch of the Cincinnati Arch, separates the Appalachian Basin (sensu stricto) from the Black Warrior Basin in Alabama and Mississippi (Thomas, this volume). In its narrower dimension, the Appalachian Basin extends from an eastern edge buried beneath Piedmont thrust sheets (Cook and Oliver, 1981), westward to the crest of the Cincinnati Arch. The basin is ovoid; its deepest part lies in eastern Pennsylvania. The strata that fill the basin are only a few thousand meters thick on the western basin margin and thicken to about 13,000 m to the north and east (Colton, 1970). Thickness variations reflect the change in composition of basin-filling strata, from strata dominated by limestone and dolomite in the south and west to strata dominated by quartz sand, silt, and clay to the north and east. The last major synthesis of Appalachian Basin stratigraphy is that published by Colton (1970). This chapter is a generalized summary of the stratigraphic development and filling of the Appalachian Basin, from its inception in the late Precambrian to its deformation at the end of the Paleozoic. Variations in stratigraphic nomenclature reflect the multiplicity of sources used in the compilation. Supplementary tables (Tables 1-7) of stratigraphic terminology contain the names of units not discussed in the text. The

Abstract The Chestnut Ridge fenster area is located southeast of Ewing, Lee County, Virginia, in parts of the Coleman Gap, Ewing and Back Valley 7½-minute Quadrangles (Fig. 1). From Ewing, Virginia, proceed northeast 1.7 mi (2.7 km) on U.S. 58, turn right on Lee County road 744; proceed 1.1 mi (1.8 km) toroad fork, take right fork. (Route has been on rocks of the Knox Group; outcrops of the Maynardville Formation are exposed on left side of road 0.7 mi [1.1 km] south of road fork.) The fenster is exposed in the road and adajcent fields 1.0 mi (1.6 km) south of the road fork 0.3 mi (0.5 km) beyond the Maynardville Formation exposure.

Abstract Ocoee Gorge is located along U.S. 64 in southeastern Tennessee in the western edge of the Blue Ridge (Fig. 1). Getting to this location is relatively easy, although parking conditions and access to the rocks vary considerably along the highway. Parking is readily available at Parksville Dam at the west end of the series of stops to be described. However, at Maddens Branch adequate parking is available for only one bus or four vans. The shoulders along the highway at both of these stops provide limited walking space, and the traffic moves very fast. Pay attention to the traffic at both Parksville Dam and Maddens Branch. Boyd Gap at the east end of the site contains adequate parking and plenty of room to walk and look at rocks.