WYNN, THOMAS C., and J. FRED READ, Virginia Tech, Dept. of Geological Science, Blacksburg, VA

ABSTRACT: Well-Cuttings Based High Resolution Sequence Stratigraphy of the Mississippian Carbonate Ramp in the Subsurface of the Appalachian Basin, West Virginia, USA

Well-cuttings and wireline logs are being used to develop a high resolution sequence stratigraphy to better understand the tectonic and eustatic controls on reservoir distribution and stacking of the 50 to 500m thick mixed carbonate-siliciclastic ramp facies of the Mississippian Greenbrier Group. Detailed high resolution regional (150km-long) cross-sections are being constructed for the first time. The regional cross-sections show five 3rd order sequences (each 10 to 50 m thick) composed of two to five, 4th order high frequency sequences. Third order and high frequency sequences consist of updip lowstand red beds and ramp margin shallow-marine sands, semi-regional transgressive shales, and high-stand quartz peloidal grainstone (dominantly eolian), peritidal lime mudstone, peloid grainstone, oolite, skeletal grainstone, open marine wackestone/mudstone and shaly slope mudstone. Along the ramp margin sequence boundaries overlie upward-shallowing slope to back facies and lowstand sands backed by transgressive shales. Up-dip sequence boundaries overlie red beds, caliches andor eolianites.

A regional linear high separates the relatively stable shallow ramp from the more rapidly subsiding basin. Even though subsidence rates in updip and downdip areas differ by an order of magnitude, it was the eustatic signal that generated the 3rd and 4th order sequences, which can be traced into the Illinois Basin. The 3rd order sequences appear to correlate with the Ross and Ross (1987) sea level curve.

This abstract is on pages 1876-1877.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid