Clay Mineralogy, Provenance, and Sequence Stratigraphy of Upper Ordovician Shales in Eastern Ohio

Abstract

A combination of x-ray diffraction analyses of core data and spectral gamma ray logs were used to interpret the largely shale succession of the Late Ordovician between the top of the Trenton Limestone and the Queenston Shale in the subsurface of east-central Ohio. The four county study area is within the back-bulge region of the foreland basin associated with the Taconic Orogeny. The XRD data from the basal portion of the section reveal an increase upward in chlorite and quartz along with a decrease in carbonate, which is consistent with an increase in detrital rather than authigenic clays. Detrital chlorite is a common clay mineral in sediments shed from mountain belts and the appearance of the clay allows constraints to be placed on the transition from under to overfilled foreland basin. Isopach maps of six 4th-order sequences from 300 wells show that subsidence across the area was consistent and augmented by some combination of compaction over pre-existing structural and depositional features.

AAPG Datapages/Search and Discovery Article #90258 © 2016 AAPG Eastern Section Meeting, Lexington, Kentucky, September 25-27, 2016