Morphology of Florida escarpment chemosynthetic brine seep community sites: deep-tow, seabeam, and GLORIA surveys
The Florida Escarpment near 26/degree/N was surveyed with Deep-Tow, Seabeam, and GLORIA in the area where chemosynthetic communities were discovered via ALVIN in the abyssal Gulf of Mexico. Seabeam bathymetry and GLORIA images indicate that the escarpment is a generally straight cliff with average slopes of about 45/degree/ from 2200 to more than 3250 m. The escarpment's face is cut by 2-km wide box canyons whose head walls are as steep as the intervening escarpment's face. The shapes of these canyons are difficult to explain with the traditional models of canyon formation. Sidescan sonar images and bottom photographs reveal that the escarpment's face is composed of a series of long, straight bedding-plain terraces which are truncated along nearly vertical orthogonal joints. Exposure of these truncated strata indicate the face of the escarpment is eroded. The contact between the basal escarpment and the flat-lying abyssal hemipelagic sediments is abrupt. Basal talus is uncommon because the abyssal floor is part of the distal Mississippi fan which is rapidly burying the escarpment. However, where talus occurs, it is in tongues of angular megabreccia of meter- and larger-sized blocks which indicate periodic catastrophic collapse. Sidescan images reveal bands of contrast in the reflective texture of the sea floor that extends 10-20 m from the base along more than 10% of the surveyed area. Photographic surveys show that these areas are associated with communities of abundant organisms. Apparently chemosynthetic communities line extensive sections of the escarpment base where reduced brines seep out into the sea floor. The morphology suggests joints and deep seeps are controlling factors in scarp retreat.
- Research Organization:
- Univ. of North Carolina, Chapel Hill (USA)
- OSTI ID:
- 5797639
- Report Number(s):
- CONF-880301-
- Journal Information:
- AAPG Bull.; (United States), Vol. 72:2; Conference: Annual meeting of the American Association of Petroleum Geologists, Houston, TX, USA, 20-23 Mar 1988
- Country of Publication:
- United States
- Language:
- English
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