STRUCTURAL ARCHITECTURE OF NORTH MISSISSIPPI: A NEOTECTONIC MODEL FOR THE SOUTHERN EXTENSION OF THE REELFOOT AULACOGEN

A structural model was constructed for north Mississippi using public and proprietary surface and subsurface data augmented by published and proprietary magnetic data. A transition from the typical rift block style associated with the Reelfoot Aulacogen to the transform pull-apart fault style in the Black Warrior Basin is evident. The tectonostructural transition involves the Bolivar-Mansfield Fault Zone (BMFZ) and Chesapeake Tectonic Zone (CTZ) as mapped by Cox. The CTZ is equivalent to the Jacksonville and Livingston fault zones (Jacksonville-Livingston Tectonic Zone, JLTZ) mapped by Oxley. The BMFZ exhibits rift architecture expressed as block faulting, yet appears sympathetic to the Black Warrior fault system in northeast Mississippi. The primary fault set of the Black Warrior Basin fault system converges in to the CTZ. Seismicity of the northeast-southwest strand of the New Madrid Seismic Zone terminates at the intersection with the BMFZ, suggesting a change in tectonic regime. Northwest-southeast trending seismicity associated with the CTZ-JLTZ evidences the change in tectonic regime. In addition, structural contours on Tertiary-age sediments in north Mississippi indicate greater tectonic activity than previously known in the southern extension of the Reelfoot Aulacogen.