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ABSTRACT: Effect of Slope Processes on Shallow Salt Body Orientation, Northwest Gulf of Mexico

Joseph Carl Fiduk

Detailed structure mapping, using 7000 km of multifold seismic data, of the salt along the upper slope within the Garden Banks and East Breaks areas of the northwest Gulf of Mexico has identified three basic types of salt structures: (1) diapirs, (2) ridges, and (3) sheets. These interpreted salt structures are a direct response to differential loading by prograding sediments and have both strike and dip orientations. The dip orientations indicate that strike-oriented structures may have been modified by slope processes (i.e., the downslope gravity mass transport of sediment).

Seismic sequence analysis of surrounding intraslope basins reveals the presence of one large, infilled, submarine canyon directly downdip from a large shelf-edge delta. This canyon runs downslope parallel to several dip-oriented salt ridges, but has an erosional relationship with several intervening strike-oriented salt structures. The associations observed between this canyon and the dip-oriented salt structures, in an area where strike-oriented structures should dominate, suggest that erosion and sediment loading associated with sediments moving downslope may have created these dip-oriented salt bodies in three ways: (1) by erosionally dissecting strike-oriented bodies, (2) by dissecting strike-oriented bodies through direct sediment loading, or (3) by thrusting salt from strike-ori nted features by updip sediment loading. Dip-oriented salt structures, therefore, may indicate dominant sediment transportation pathways, where coarse clastic sediments are carried from the shelf edge into deep water.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990