NEWLY IDENTIFIED EOCENE THRUST FAULT, TIPTON COUNTY, TN, AND IMPLICATIONS FOR EARLY-EOCENE STRESS FIELD

Along the Mississippi River bluff line in Shelby and Tipton Counties, TN, lies the complex intersection of the eastern margin of the Reelfoot Rift, the Meeman-Shelby Fault, and a newly identified thrust fault, the tentatively named Sugar Creek Fault. The Eastern Reelfoot Rift Margin is a seismically active fault zone which strikes approximately N45E and shows right-lateral focal-plane mechanism solutions. Investigations in Shelby County have revealed evidence of Quaternary and Holocene fault offsets on the Meeman-Shelby fault, a high-angle reverse fault striking N25E, showing right-lateral strike slip. Both the Rift Margin and Meeman-Shelby Fault are consistent with the modern E-W stress field. Further northeast, mapping of Eocene through Holocene strata exposed in Sugar Creek in Tipton County has revealed a thrust fault striking N80E, the Sugar Creek Fault, which is exposed in at least three creek beds. The fault forms a front between a more or less undeformed footwall and a hangingwall containing beds which dip ~10-25^o NW and other subsidiary deformational features. In the thrust hanging wall, Claiborne strata dipping northward are overlain in angular unconformity by horizontal Claiborne strata, suggesting that the majority of the deformation occurred during the Eocene, and that the fault has been largely quiescent since that time. The strike of the Sugar Creek Fault is consistent with an Early Cenozoic N-S stress field. Ongoing fieldwork seeks to constrain the trend and length of the Sugar Creek Fault, which contributes to our understanding of Early Cenozoic deformation in the midcontinent.