The Geological Environment West of St. Croix
NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY STENNIS SPACE CENTER MS
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Geological and geophysical data collection efforts over the past 15 years were augmented in early 1976 with 12 kHz bathymetry, together with 3.5 kHz and low- frequency seismic reflection data, collected on NS and EW gridlines at 300 meters m line spacing, plus extensive bottom photographs and several videotapes. A small plateau with a gently tilted, low-relief surface, lies west of the island slope of St. Croix at 800-1,200 m depth. The plateau is dissected by three submarine canyons. Rock outcrops are largely confined to the walls of the canyons, whereas the rest of the plateau is underlain by at least a surface veneer of unconsolidated carbonate ooze -- predominantly silty calcilutites with an 85 average carbonate content. Two of the canyons are clearly erosional in origin, whereas one appears to have been associated with a prograding sedimentation regime in which a plain and natural levee were formed. Three stratigraphic units are identifiable in the seismic sections of the area based on their acoustic character. The area is seismically active today, and may be expected to undergo occasional moderate earthquakes. Destructive earthquakes, although rare, are an ever present possibility.
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy