Texas A&M University
Department of Oceanography
Gulf geology 101
Need a little background information about the seafloor in the Gulf of Mexico?
Newly discovered seafloor channels formed by super-salty, flowing water
History
An unusual set of geological events
brings 70 million-year-old salt near the seafloor in the northwestern Gulf
of Mexico. During Jurassic time, North America separated from South America.
The semi-enclosed basin formed by this separation, the Proto-Gulf of Mexico,
was partially filled with salt after the seawater evaporated. Up to 4,000
meters of salt was deposited in the area that is now south Texas and the
Texas and Louisiana continental margin.
Under the weight of salt and sediment, the gulf basin
deepened. The buried salt started to migrate upward, because salt is highly
plastic and readily moves under pressure from a large deposit of sediment.
The upward movement of salt along the rim of the basins
in the gulf created zones of highly faulted layers of sediment. The combination
of salt near the seafloor and tectonic activity along the rims of basins
allowed seawater to access and to dissolve the shallowly buried Jurassic
salt. The solution was expelled along faults at the seafloor as high-density
brines.
In the case of Vaca Basin, the brine flowed down the
basin walls and formed the brine-flow channels in the soft, muddy Holocene
sediments that cover the basin.
Brine-flow channels were found in Vaca Basin, shown here in a shaded bathymetry image [660K] of an area on the lower continental slope. Vaca Basin is 2,650 meters deep and is a "supralobal" basin - a basin formed by the withdrawal of salt.
http://oceanography.tamu.edu/Quarterdeck/1998/3/bryant-2.html
Copyright 1998-1999, Department
of Oceanography, Texas A&M University.
Updated November 24, 1998. (abdw)
Send Quarterdeck inquiries to quarterdeck@ocean.tamu.edu.
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