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LOWRIE, A., Consultant, Picayune, MS, N. M. SULLIVAN, Earth Science and Resources Institute, University of South Carolina, Columbia, SC, M. A. FOGARTY, Exploration Systems, Inc., New Orleans, LA, C. J. KROTZER, Metairie, LA, J. CARTER, Shreveport, LA, and I. LERCHE, University of South Carolina, Columbia, SC

ABSTRACT: Sequence Stratigraphy and Modeling of the North Louisiana-South Arkansas Basin

Analysis of electric log and seismic reflection data in the North Louisiana-South Arkansas (NL-SA) basin reveals that sequence stratigraphic techniques may be applied to this peripheral basin underlain by continental crust. Major interpretational difficulties result from the high rate of basin subsidence relative to low sedimentation rates, as contrasted with the more usual situation of passive continental margins where sedimentation generally exceeds regional subsidence. Similarly, sediments along passive margins with a large fluvial drainage system tend to be terrigenous clastics with low structural strength. Sediments along the shelves of peripheral basins in a tropical environment, such as NL-SA, characteristically include carbonates of high structural strength. These "strong" lay rs have served as barriers to the rise of buoyant salt pillows, inhibiting the growth of salt diapirs. Occasional diapirs exist where sufficient salt has accumulated to provide enough buoyancy to rupture restraining carbonates. Diapirism in the deeper part of the basin suggests that less "strong" layers were deposited there.

Pronounced basement tectonics acts as a break between salt pillows in the central basin slope and in basement horsts, which serve as bases for the few salt diapirs, in the deeper south basin. The salt pillows rose with the progradation of the Smackover and Cotton Valley formations. Deposition proceeded from north to south, suggesting that the basin began with Triassic rifting. Examples of onlap abound as deposition prograded up to and then engulfed the rising salt pillows. Water depth apparently increased into the basin, as evidenced by onlapping. Abundant channeling, both erosional and aggradational, and major deltas also are identified within highstand and lowstand sequences.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.