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ABSTRACT: Large-Scale Patterns of Recent Sedimentation Along the Cayman Trough Pull-Apart Basin, Caribbean Sea

David Debalko, Paul Mann

The North American-Caribbean plate boundary zone consists of a broad zone of active strike-slip deformation that extends 3200 km from Middle America to the Lesser Antilles. An 1100-km-long, 100-km-wide pull-apart basin, the Cayman Trough, is the dominant structural element of the submerged central part of the plate boundary zone between Jamaica and Honduras. In order to investigate large-scale patterns of recent sedimentation in a fully marine pull-apart setting, we surveyed a 90,000-km2 area along the southern edge of the Cayman Trough using SeaMARC II side-scan sonar, 3.5 KHz, and digital single-channel reflection techniques. These data allow us to divide the southern margin of the Cayman Trough pull-apart into three provinces of recent sedimentation: (1) an astern terrigenous province characterized by straight, short canyon systems (average 1-3 km wide and 10-15 km long) and associated small, lobate fans; canyon-fan systems are sourced by clastic spillover from filled borderland-type basins and by erosion of emergent fault-block islands; (2) a central carbonate province characterized by periplatform carbonate detritus fringing four isolated carbonate banks which collectively make up the Nicaraguan Rise; canyon systems (1-3 km wide, 15-80 km long) are highly meandering when unfaulted and straight when faulted; and (3) an eastern carbonate and terrigenous province characterized by both carbonate sediments shed off the easternmost bank of the Nicaraguan Rise bank and by terrigenous sediment derived from Jamaica.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990