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Louann Salt Advances with Variable Deposition Rates from Highstand to Lowstand and Impacts on Geologic Processes in Deep-Water, Northern Gulf of Mexico

A. Lowrie1, S. J. Moffett1, T. Klekamp2, I. Lerche3, and N. M. Sullivan4
1Consultant, Picayune, MS
2El-Can Exploration, Inc., Mandeville, LA
3Department of Geology, University of South Carolina, Columbia, SC
4Consultant, Houston, TX

The purpose of this paper is multi-fold: a) to focus awareness on major geologic processes and  b) to present preliminary notions of synergy between processes in deep-water, sub-salt and fanfold belt environments. With as much as a thousand-fold variation in deposition rates from highstand to lowstand during the Quaternary, and probably the Neogene, the rates at which processes operate over time are highly variable. Synergy between processes, including those related to specific zones, i.e. sub-salt and basement, is connected via sedimentation rate variation and rate and extent of Sigsbee Salt basinward migration as the ever-growing, salt-floored sub-basin advances through the northern Gulf of Mexico continental margin.

Synergistic geologic processes between deep-water, sub-salt, and fanfold belt are compiled: hydrates and hydrodynamics of hydrate stability zones, earthquakes and paleo-fracture zones with thermal anomalies and contained fluids, fracture development and gas expansion/contraction, fanfold belt development, sub-salt pressure compartments, major deposition rate variations, and implications of salt-floored sub-basins.

Salt has twice to triple the thermal conductivity of an alternating sand and shale sediment. Salt massifs, ridges, and diapirs can be as much as 20o - 40o C hotter than surrounding sediments. The advancing salt-floored sub-basin can thermally mature organics that have been deposited and make them available for accumulation in reservoirs as commercial hydrocarbons.

AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana