CONSOLIDATION PATTERNS DURING INITIATION AND EVOLUTION OF A PLATE-BOUNDARY DECOLLEMENT ZONE - NORTHERN BARBADOS ACCRETIONARY PRISM

Borehole logs from the northern Barbados accretionary prism show that the plate-boundary decollement initiates in a low-density radiolarian claystone. With continued thrusting, the decollement zone consolidates , but in a patchy manner. The logs calibrate a three-dimensional seism ic reflection image of the decollement zone and indicate which portion s are of low density and enriched in fluid, and which portions have co nsolidated. The seismic image demonstrates that an underconsolidated p atch of the decollement zone connects to a fluid-rich conduit extendin g down the decollement surface. Fluid migration up this conduit probab ly supports the open pore structure in the underconsolidated patch.