ABSTRACT: Sea-Level Fluctuations, Paleocene Middle Wilcox Stratigraphy and Hydrocarbon Distribution in East-Central Louisiana

ECHOLS, JOHN B., and DON A. GODDARD, Basin Research Institute, Louisiana State University, Baton Rouge, LA

Stratigraphy of the upper lower Wilcox and middle Wilcox of east central Louisiana developed, in part, as a function of sea level fluctuation in the upper Paleocene. Beginning in upper lower Wilcox, a major fall in sea level resulted in basinward progradation of thick, massive Minter distributary channel sands. With ensuing sea level rise, a long period of transgression followed. Oil production commonly is found in the upper Minter beds "on the cusp" between the sea level fall and rise. The detailed relationships between the fluctuations, sediments and hydrocarbon occurrence in this interval must be understood.

The extended period of sea level rise produced a transgressive systems tract (TST), the Baker Shale TST, which includes the Nichols and Artman transgressive barrier oil sands of Lake Curry field of T4N, R6E, Concordia Parish, Louisiana. The Baker Shale TST is overlain by the C5/Turner, a basin margin facies equivalent of a condensed section. A succession of aggradational parasequences follows the C5/Turner.

They are overlain, in turn, by the Big Shale TST. Oil is found in A-1 transgressive barriers near the base of the Big Shale TST. The upper surface of the Big Shale TST may be an incised valley system formed during a dramatic sea level fall dated at 54.8 Ma.

Stratigraphic evidence suggests that the sea level curve cited in this paper is probably more irregular and without the smoothness shown.

AAPG Search and Discovery Article #91014©1992 AAPG GCAGS and GC-SEPM Meeting, Jackson, Mississippi, October 21-23, 1992 (2009)