Subsurface sandstone samples of the Upper Jurassic (Oxfordian) Norphlet Formation erg deposits and (Kimmeridgian) Haynesville Formation sabkha deposits were collected from wells in the eastern Gulf of Mexico for U-Pb detrital zircon provenance analysis. Norphlet Formation samples in southwestern Alabama are characterized by detrital zircon ages forming two dominant populations: (1) 265–480 Ma, associated with Paleozoic Taconic, Acadian, and Alleghanian orogenic events of eastern Laurentia, and (2) 950–1250 Ma, associated with the Grenville orogenies of eastern Laurentia. These detrital zircon ages indicate derivation from Laurentian and Laurentian-affinity sources, including erosion of Paleozoic strata of the remnant Alleghanian fold-and-thrust belt and Black Warrior foreland basin, as well as Laurentian cratonic rocks exposed in remnant Appalachian orogenic highlands and eastern Gulf of Mexico rift-related horst blocks. In contrast, Norphlet Formation samples from the offshore Destin Dome exhibit a major population of 540–650 Ma zircon grains, along with a small population of 1900–2200 Ma zircon grains; these ages are interpreted to indicate contribution of sediment to the Norphlet erg from peri-Gondwanan terranes sutured to eastern Laurentian, as well as from the Gondwanan Suwannee terrane, which remained attached to North America after the rifting of Pangea. Samples from south-central Alabama yield subequal proportions of four major age populations: 250–500 Ma, 520–650 Ma, 900–1400 Ma, and 1950–2250 Ma. These ages indicate sediment was sourced by both Laurentian/Laurentian-affinity and Gondwanan/Gondwanan-affinity rocks, either through a combination of these rocks in the source area, or intrabasinal mixing of Laurentian/Laurentian-affinity sediment with Gondwanan/Gondwanan-affinity sediment. Detrital zircon provenance data from the overlying Haynesville Formation clastics of the Destin Dome offshore federal lease block also show the signature of Gondwanan/Gondwanan-affinity sediment input into the eastern Gulf of Mexico, suggesting that paleotopography affecting Norphlet Formation deposition persisted throughout much of the Late Jurassic. However, samples from the Pennsylvanian Pottsville Formation synorogenic fill of the Black Warrior Basin and Middle Cretaceous Rodessa Formation marginal marine sandstone lack evidence for any significant contribution of Gondwanan or Gondwanan-affinity detritus to the basin, indicating that transport of Gondwanan/Gondwanan-affinity zircon to the eastern Gulf of Mexico was due to early Mesozoic uplift, erosion, and/or paleodrainage pattern development. These results, along with previously reported detrital zircon provenance of Triassic and Jurassic sandstone of the southern United States, suggest that early Mesozoic sediment supply in southern North America was closely associated with erosion of Gondwanan/peri-Gondwanan crust docked along the Suwannee-Wiggins suture, which likely extended westward from the Suwannee terrane to the Yucatan-Campeche terrane; much of this Gondwanan/peri-Gondwanan crust remained docked along the Suwannee-Wiggins suture after the rifting of Pangea and prior to opening of the Gulf of Mexico.

Data from thousands of coalbed methane wells, conventional oil and gas wells, and five regional seismic-reflection profiles show evidence of relationships among multiple extensional events and Appalachian thrusting in the area of the Alabama Promontory and Black Warrior Basin. The oldest extensional event is of late Precambrian to early Middle Cambrian age, associated with Iapetan rifting. Along the southeastern margin of the promontory, in the northeastern part of the Birmingham graben system, a fill sequence older than the Rome Formation (Early Cambrian) is inferred. Normal faults along both sides of the promontory were active from Early Cambrian to early Middle Cambrian, as indicated by expanded hangingwall sections of the Rome and Conasauga Formations. In the Black Warrior Basin, some basement-involved normal faults were active during deposition of the Ketona and Knox carbonates (Late Cambrian–Early Ordovician). Middle Cambrian to Early Ordovician extension coincided with the inception and opening of the Rheic Ocean. Small amounts of growth occurred on some normal faults and on folds at the leading edge of the Appalachians during deposition of the Pottsville Formation (early Pennsylvanian, Morrowan). Major thin-skinned and basement-involved normal faulting occurred in the Black Warrior Basin after deposition of the preserved Pottsville section, probably during Atokan time. The extensional thin-skinned detachments are in or at the base of the Pottsville Formation and the top of the Conasauga Formation. Major Appalachian thrusting occurred after the main episode of normal faulting, perhaps during the late Pennsylvanian.

Abstract During the past 25 yr, several different tight-gas sandstone reservoirs have been brought into the nation’s productive natural-gas inventory. These include reservoirs of many different ages in many different basinal settings. In this chapter, reservoir discovery and management efforts at select fields in the Silurian Tuscarora, Devonian Oriskany, Pennsylvanian Pottsville and Jackfork, Jurassic Cotton Valley, Cretaceous Frontier and Almond, and Eocene Wilcox sandstones are reviewed, compared, and contrasted. Each of these target reservoirs is unique and both simple and complex. However, from a general understanding of the characteristics and variety of tight-gas reservoirs, a set of common generalities can be developed that may even be developed into rules for discovery. Although many tight-gas sandstone reservoirs may be classified as continuous-type reservoirs, (i.e., unconventional gas accumulations lacking well-defined field boundaries), tight-gas sandstone reservoirs are complexly subtle, with reservoir properties that are anything but continuous across their extent. Intentional discovery and development of tight-gas sandstone reservoirs requires knowledge, planning, careful execution, flexibility, and patience. A discovery model for the exploration and development of tight-gas sandstone reservoirs is proposed: (1) locate wells within a dry, gas-prone basin or part of the basin to avoid liquid (water, crude oil, or condensate) production, which will hurt gas-production rates; (2) select as intended targets depositionally heterogeneous reservoirs (i.e., channel systems), which are close to organic-rich intervals; (3) target slightly higher-shale-content sandstones instead of lower-shale-content sandstones (quartz arenites) to avoid loss of reservoir storage volume caused by cementation; (4) take advantage of whatever structure there is, and drill as high up on that structure as possible; (5) consider how you plan to manage a fractured, tight-gas reservoir (if fractures are anticipated to be present); (6) try to avoid sandstones with the potential for high water flow and low gas flow; (7) develop a clear petrophysical understanding of the reservoir early in the life of the field; and (8) plan on infill drilling once the initial spacing unit design is approved and implemented.

Continental crust is recycled into orogenic forelands by the distinct but inter- related processes of tectonic imbrication and sedimentary dispersal. Tectonic loading by the orogen drives flexural subsidence of a foreland basin, and the orogen provides a source of sedimentary detritus to fill the basin. Detrital zircons in Pennsylvanian-age sandstones in the Appalachian (Alleghanian) foreland basin reflect an Alleghanian orogenic source of recycled and primary detritus from Grenville-age basement rocks and Iapetan synrift rocks, which also yield pre-Grenville recycled craton-derived detrital zircons. Minor contributions are from Taconic- and Acadian-age plutons and accreted Gondwanan terranes. Ages of the detrital zircons show that most of the synorogenic clastic-wedge sediment was recycled from older continental crustal rocks. Cratonward thrusting of crystalline thrust sheets over the foreland recycles continental crustal rocks from the continental margin and thickens the continental crust. Along the Alleghanian foreland, the Blue Ridge thrust sheet of crystalline basement rocks and Piedmont thrust sheets of metasedimentary rocks represent imbrication and thickening of rocks of continental crustal composition. Both tectonic imbrication in foreland thrust sheets and sediment dispersal into the foreland basin recycle and thicken continental crust.

Multiple levels of frontal ramps and detachment flats accommodate tectonic shortening in contrasting deformation styles at different levels in a mechanically hetero geneous stratigraphic succession in a foreland thrust belt. The late Paleozoic Appalachian thrust belt in Alabama exhibits a balance of shortening in contrasting deformation styles at different stratigraphic levels. The regional décollement is in a weak unit (Cambrian shale) near the base of the Paleozoic succession above Precambrian crystalline basement rocks. Basement faults, now beneath the décollement, controlled the sedimentary thickness of the Cambrian shale and the location of high-amplitude frontal ramps of the regional stiff layer (Cambrian-Ordovician massive carbonate); shortening in a mushwad (ductile duplex) from thick Cambrian shale is balanced by translation of the regional stiff layer at a high-amplitude frontal ramp above a basement fault. A trailing, high-amplitude, brittle duplex of the regional stiff layer has a floor on the regional décollement and a roof that is also the floor of an upper-level, lower-amplitude, brittle duplex. The roof of the upper-level brittle duplex is a diffuse ductile detachment below an upper-level mushwad, with which parts of the brittle duplex are imbricated. The basal detachment of the upper-level mushwad changes along strike into a frontal ramp at a location coincident with a sedimentary facies change in the weak shale unit that hosts the mushwad. The roof of the upper-level mushwad is a brittle massive sandstone. Shortening on the regional décollement is balanced successively upward through contrasting tectonic styles in successive mechanically contrasting stratigraphic units.

Abstract The thickest and most laterally continuous upper Carboniferous molasse in the central Appalachians is located in the Southern Anthracite Field of northeastern Pennsylvania. Substantial deposits extend throughout northeastern Pennsylvania where >90% of the total anthracite (original reserves) in the United States and the thickest coal beds of the eastern United States are located. The abundance of and demand for this resource allowed the region to prosper in the nineteenth and twentieth centuries. In Pottsville, Pennsylvania, the exposed Upper Mississippian to Middle Pennsylvanian molasse reveals a progressive evolution from a semiarid alluvial plain to a semihumid alluvial plain to a humid alluvial plain. The anthracite beds occur and thicken with increased humid conditions. The progression is also exposed in Tamaqua, Pennsylvania, where convenient access to the underlying Lower Mississippian strata is available, thus providing a section of all Carboniferous formations in the region. Finally, in Lansford, Pennsylvania, a renovated deep anthracite mine illustrates the historical methods and working conditions that existed to extract the valuable resource and allow the region to flourish and fuel the Industrial Revolution.

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.