Abstract: Evidence for Mississippian Structural Activity Above a Precambrian Rift System, South-Central Kentucky

Garland R. Dever Jr.

Erosional and depositional features in Mississippian limestones of south-central Kentucky suggest the influence of coeval structural activity. The Greenwood Anomaly, a large north-trending gravity anomaly, underlies Paleozoic rocks in the area. It is considered to be part of a Precambrian rift system. The Grenville Front, identified as the western margin of a Proterozoic Grenville allochthon, extends along the west side of the Greenwood Anomaly.

Several lines of evidence, mainly involving the St. Louis Limestone and Ste. Genevieve Limestone Member of the Monteagle Limestone, suggest Mississippian reactivation of faults associated with the Greenwood Anomaly and the Grenville Front. Subaerial exposure of St. Louis sediments and depositional thinning of lower Ste. Genevieve sediments apparently resulted from local uplifts produced by reactivation of rift-related faults. Broader uplift later interrupted Ste. Genevieve deposition across the Greenwood Anomaly and was followed by development of an extensive erosional surface cut into lower Ste. Genevieve and upper St. Louis deposits. Faulting also is indicated by thickness variations in Mississippian units across

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas