The New Madrid Rift System — Its Role in the Evolution of the Illinois Basin

Abstract

The New Madrid Rift System, underlying the Mississippi Embayment and the southern end of the Illinois Basin, consists of the Reelfoot Rift and a dog-leg extension in western Kentucky known as the Rough Creek Graben. Seismic reflection sections indicate that the rift system consists of several half-grabens linked by accommodation zones much like those observed in the East African Rift. In northeastern Arkansas and western Tennessee, the rift is characterized by opposing-polarity half-grabens separated by a central uplift known as the Blytheville Arch. In southern Illinois and western Kentucky, where the rift curves eastward into the Rough Creek Graben, a shallow half-graben occurs at the southern edge of the rift. Eastward, across an apparent accommodation zone, the polarity reverses and a deep half-graben is developed along the north side of the Rough Creek Graben.