Detailed structure and possible fluid paths at the toe of the Barbados accretionary wedge (ODP Leg 110 area)

Abstract

During the summer of 1987, a bottom-navigated heat-flow and deep-tow side-scan-sonar survey was carried out over the toe of the Barbados accretionary wedge, in the Ocean Drilling Program (ODP) Leg 110 drilling area. Surface traces of the Leg 110 drill holes were recognized on the sonar images. Precise relocation of the ODP holes relative to a reference multichannel seismic line led to a new interpretation of some of the structures previously described by the Leg 110 scientific party. For example, one thrust formerly interpreted as a forward-propagating major thrust is interpreted here as a near-surface backthrust developed above a probable shallow decollement located at the base of the Pleistocene sequence. We use these new structural data as surface guidelines in building a balanced cross section of and defining a fluid-flow pattern within the toe of the wedge. Using new, closely spaced heat-flow data, we discuss briefly the fluid flow along the major fractures through the wedge.