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Sea Level Highstand Shales and Thin Stacked Deltas: Paleocene Middle Wilcox of Central Louisiana and Southwest Mississippi

ECHOLS, JOHN B., Louisiana State University, Baton Rouge, LA

The Wilcox Group is subdivided into the lower, middle, and upper Wilcox. The newly created middle Wilcox subdivision has produced most of the nearly 1 billion bbl of oil from the Wilcox of east-central Louisiana and southwest Mississippi.

The E-2/C5/Turner parasequence set is bounded by the Big shale transgressive systems tract above and the Baker shale transgressive systems tract below. A stratigraphic model is developed for the E-2/C5/Turner parasequence set. The set is a thin (~90 m = 300 ft), highstand systems tract, aggradational parasequence set.

A sea level rise during Baker shale deposition resulted in a transgression of older delta deposits, forming oil-producing transgressive barriers, shoals, and related sands. These sands are analogs of Holocene stratigraphic models of the coastal areas and nearshore locations of Louisiana and Mississippi. The E-2/C5/Turner parasequence set provides no analogs to modern stratigraphic models.

The model established in this paper for the E-2/C5/Turner parasequence set describes cyclic deposition of a constructive interval of shallow marine, bay-fill shale overlain by bay-fill sand overlain by a thin lignite. In part, the model seeks to develop predictive procedures for mapping and locating optimal drilling locations for potential reservoirs of the aggradational parasequence set, an important oil-producing set in east-central Louisiana and southwest Mississippi.

 

AAPG Search and Discovery Article #91006 © 1991 GCAGS and GC-SEPM Meeting, Houston, Texas, October 16-18, 1991 (2009)