Interrelationships between Downslope Sediment Transport and Salt Tectonism

BEHRENS, E. WILLIAM, University of Texas Institute for Geophysics, Austin, TX

Echo characteristics of high resolution (3.5 kHz) seismic reflection profiles were used to map the distribution of coarsely textured shelf sediments transported downslope by turbidity current and/or mass transport processes. Piston cores provided ground truth for the interpretation of sediment character; and multichannel reflection data showed the distribution of salt structures. Where salt is extensive but occurs in more or less distinctly isolated structures, it creates interdomal intraslope basins that are successively filled from upslope to downslope. The extent of bypassing of filled basins (i.e., the extent of downslope transport) may vary considerably over short distances along strike. Pathways may be clearly discernable or quite enigmatic. Where salt structures are more sparse sediments flow downslope, around the bathymetric highs created by the diapirs, in broad or narrow valleys that are structurally controlled. Where salt structures are so extensive that they form coalescing canopies (lower slope), they broadly pond downslope flow. However, downslope flow may continue through the salt complex along channels following canopy sutures and transit the entire slope. The Alaminos Canyon Fan is evidence of shelf sediments bypassing the entire slope in spite of very extensive salt diapirism.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)