High Frequency Sequence Stratigraphic Controls on Stratal Architecture of an Upper Pennsylvanian “Regressive Limestone” (Bethany Falls Limestone), Midcontinent, USA
Graham J. Butler
Department of Geosciences, Texas Tech University
The Bethany Falls Limestone (BFL) is the “regressive” carbonate member of the Swope high frequency sequence as developed on the northern platform of the Mid-continent Basin. It is underlain by the condensed, maximum flooding Hushpuckney Shale and is overlain by the lowstand Galesburg Shale. The Swope sequence is Early Missourian in age and is a significant hydrocarbon reservoir unit in western Kansas. Extensive local-scale outcrop and near surface research have been conducted on the oolite facies of the BFL because it is typical of Upper Pennsylvanian reservoir facies in the subsurface. However, this study focuses on the platform-scale architecture of the BFL to examine the potential for recognizing internal flooding surfaces and therefore delineating ramp clinoform geometries within the BFL. The distribution and diagenesis of the oolite facies as developed in the BFL across the Mid-continent platform can then be compared within this high-resolution sequence stratigraphic framework.
Preliminary results indicate that flooding surfaces, marked by shale breaks within the BFL, are correlative across the platform and basinward. At least three very high frequency sequence boundaries are apparent within the initially studied outcrops, although more may become apparent as outcrop control increases. The distribution of carbonate lithologies within these stratal packages is consistent with basinward progradation of facies throughout clinothem deposition.
AAPG Search and Discover Article #90087 © 2008 AAPG/SEG Student Expo, Houston, Texas