Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM
Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM
Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM
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The Role <strong>of</strong> Salt in Gravitational Failure<br />
<strong>of</strong> Passive Margins<br />
Mark G. Rowan<br />
Rowan Consulting, Inc.<br />
1633 D 4 th St.<br />
Boulder, CO 80302<br />
(e-mail: mgrowan@qwest.net)<br />
Bruno C. Vendeville<br />
Bureau <strong>of</strong> Economic Geology<br />
University <strong>of</strong> Texas at Austin<br />
University Station, Box X<br />
Austin, TX 78713<br />
Frank J. Peel<br />
BHP <strong>Petroleum</strong> (Americas) Inc.<br />
1360 Post Oak Blvd., Suite 500<br />
Houston, TX 77056<br />
Abstract<br />
Salt along a passive margin facilitates and accommodates gravitational failure <strong>of</strong> the margin in several key ways.<br />
First, it serves as the basal detachment for a linked system <strong>of</strong> updip extension and downdip contraction that develops<br />
due to a combination <strong>of</strong> gravity gliding and gravity spreading <strong>of</strong> the sediment carapace. Second, proximal subsidence<br />
into salt and distal inflation <strong>of</strong> salt reduces the bathymetric slope and the associated gravity potential. Third, preexisting<br />
salt diapirs and massifs accommodate basinward translation <strong>of</strong> the overburden by lateral squeezing and the<br />
consequent extrusion <strong>of</strong> allochthonous salt. Fourth, allochthonous canopies can serve as additional detachment levels<br />
for gravitational failure. <strong>Deep</strong> water environments are where most <strong>of</strong> the shortening occurs, which is manifested as<br />
salt-cored folds, reverse faults, squeezed diapirs, inflated massifs, and extrusion <strong>of</strong> allochthonous salt. Extensional<br />
and strike-slip faults and associated salt deformation are also present, as are loading-induced features such as turtle<br />
structures and passive diapirs.<br />
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