Possible Neoproterozoic-early Paleozoic grabens in Mississippi, Alabama, and Tennessee

Abstract

Low-intensity magnetic and negative gravity anomalies in northern Mississippi, north-western Alabama, and western Tennessee are viewed as being similar to the magnetic and gravity low associated with the Mississippi Valley graben. The anomalies are interpreted as shallow grabens, and it is proposed that the grabens, like the Mississippi Valley graben, resulted from northwest-southeast extension during Neoproterozoic-early Paleozoic fragmentation of Laurentia. If real, the grabens indicate that extension affected a larger part of Laurentia than has been previously documented. They imply hitherto unsuspected oil and gas potential and, if the area is coupled to the stress field affecting the Mississippi Valley graben, represent structures that warrant evaluation for seismic risk.