The deep parts of basins in the continental United States constitute an important group of potential natural gas exploration opportunities. These frontier plays could be a valuable national resource, although they are currently not being vigorously pursued by industry. One such play is the Proterozoic-Cambrian rift-basin complex of the southeastern Midcontinent, U.S.A. Less than 0.1 percent of the wells drilled in this area have penetrated Cambrian strata beneath the Knox Group, yet it is estimated that the pre-Knox Cambrian succession alone could contain up to 43 trillion cubic feet of gas. The Cambrian Reelfoot-Rough Creek-Rome Rift System of the southeastern Midcontinent contains thick syn- and post-rift fill sequences within fault-bounded grabens and thinner, but potentially productive, intervals on its flanks. Even less well known are the underlying, complex Proterozoic rift sequences for which meager well data indicate a dominantly sedimentary nature. Regional reflection-seismic data for these older rift sequences also indicate a sedimentary origin in adjacent undrilled areas. Angular unconformities interpreted from these reflection-seismic data show that the Proterozoic rocks may be divided into two or more sequences. The unconformities and their associated pinch-outs and onlaps, together with interpreted fan complexes, could be world-class stratigraphic plays. Tilted fault blocks, horsts, and large anticlines constitute several potential structural plays associated with these rifts. These unexplored, stacked rift basins represent a plethora of trap types and potential new targets for natural gas exploration in an area crossed by a number of major natural gas pipelines serving the northeastern United States.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah