Abstract The Reelfoot rift is one segment of a late Proterozoic(?) to early Paleozoic intracontinental rift complex in the south-central United States. The rift complex is situated beneath Mesozoic to Cenozoic strata of the Mississippi embayment of southeastern Missouri, northeastern Arkansas, and western Tennessee and Kentucky. The rift portion of the stratigraphic section consists primarily of synrift Cambrian and Ordovician strata, capped by a postrift sag succession of Late Ordovician to Cenozoic age. Potential synrift source rocks have been identified in the Cambrian Elvins Shale. Thermal maturity of Paleozoic strata within the rift ranges from the oil window to the dry gas window. Petroleum generation in Elvins source rocks likely occurred during the middle to late Paleozoic. Upper Cretaceous sedimentary rocks unconformably overlie various Paleozoic units and define the likely upper boundary of the petroleum system. No production has been established in the Reelfoot rift. However, at least nine of 22 exploratory wells have reported petroleum shows, mainly gas shows with some asphalt or solid hydrocarbon residue. Regional seismic profiling shows the presence of two large inversion structures (Blytheville arch and Pascola arch). The Blytheville arch is marked by a core of structurally thickened Elvins Shale, whereas the Pascola arch reflects the structural uplift of a portion of the entire rift basin. Structural uplift and faulting within the Reelfoot rift since the late Paleozoic appear to have disrupted older conventional hydrocarbon traps and likely spilled any potential conventional petroleum accumulations. The remaining potential resources within the Reelfoot rift are likely shale gas accumulations within the Elvins Shale; however, reservoir continuity and porosity as well as pervasive faulting appear to be significant future challenges for explorers and drillers.

Abstract Sedimentary basins in the eastern United States (U.S.) contain strata ranging in age from Neoproterozoic to Holocene and have been the source of petroleum and coal that fueled much of the initial growth and development of the U.S. as a major industrial power. It is estimated that at least 87 billion barrels of oil (BBO) and natural gas liquids (BBNGL) and 664 trillion cubic feet of natural gas (TCFG) have been produced to-date from these basins. These basins developed on continental and transitional oceanic-continental crust ranging in age from the Paleoproterozoic to Triassic. Many of these basins have undergone structural readjustment and uplift, some being nearly completely inverted. The oldest of these basins considered here are Mesoproterozoic to Early Cambrian in age. They include the Midcontinent rift, Reelfoot rift, Rough Creek graben, and Rome trough. These basins are dominantly rift basins, which formed within the North American craton, presumably as a result of plate tectonic forces associated with the rifting of the Rodina supercontinent and the opening of the Iapetus Ocean. Petroleum systems have been identified or postulated in these four basins. Overlying these basins are the three large Paleozoic-aged sag-foreland basins of the eastern U.S.: the Michigan, Illinois, and Appalachian basins. Additionally included are the eastern extent of the Arkoma-Ouachita-Black Warrior foreland basin and a relict Gondwanan basin that was left behind in present-day north Florida following the Mesozoic rifting of Pangea. A mixed siliciclastic–carbonate–evaporite sedimentary section includes reservoirs and seal facies for many play types. Multiple petroleum systems have been identified or postulated in all of these basins. Succeeding these large Paleozoic sag and foreland basins are the Late Permian(?) to Early Jurassic rift basins that rim the eastern continental margin of the U.S. These basins have formed as a result of plate tectonic forces associated with the opening of the Atlantic Ocean and the Gulf of Mexico. Basin-fill sequences are generally lacustrine and continental-playa siliciclastic strata containing locally significant coals and minor carbonates. Petroleum systems have been identified or postulated in several of these basins, including the Dan River-Danville, Deep River, Newark, Richmond, and Taylorsville basins. Finally, overlying this complex stack of Proterozoic, Paleozoic, and early Mesozoic basins are the great Gulf of Mexico and Atlantic margin basins. The Gulf of Mexico Basin is distinguished by the dominating structural control of the salt and shale tectonics on a mobile substrate, whereas the basins of the western Atlantic margin are associated mainly with faulting associated with the opening of the Atlantic Ocean. Only the Carolina Trough of the western Atlantic margin basins has mobile salt structures. The sedimentary sequences of both basins are a mixed siliciclastic–carbonate interval containing coal and lignite in variable quantities in the updip portions of the basins. A composite total petroleum system has been identified in the Gulf of Mexico basin that incorporates several Mesozoic and Cenozoic petroleum source rocks with many reservoir rocks and seals throughout the sedimentary sequence. A combination of cultural and tectonic setting, sediment provenance and delivery systems, and paleo-oceanographic conditions have made the Gulf of Mexico basin one of the most prolific petroleum provinces on the planet. The current understanding of the Atlantic margin basin suggests that it does not appear to have a similar accumulation of petroleum resources as the Gulf of Mexico Basin. Correlated and potential petroleum source rock intervals have been penetrated in several of the offshore post-rift Atlantic margin subbasins; however, in many places on the shallow shelf, these intervals are generally too organically lean and (or) too immature to be major source rocks. A single petroleum system has been locally demonstrated in the offshore Atlantic by a non-commercial gas-condensate discovery. Additional petroleum systems in the western Atlantic may be identified as research continues. Source rock intervals penetrated by Deep Sea Drilling Project and Ocean Drilling Program cruises farther off-shore have generative potential, but data from these projects are too sparse to identify petroleum systems connecting these source rocks with potential reservoir targets.