The role of mobile muds in basin form and fill in the tectonic and sedimentologically complex region of the Southeastern Margin of the Caribbean Plate, Trinidad and Tobago, West Indies

Abstract

The southern portions of the Barbados Accretionary Prism and the eastern deepwater region of Trinidad and Tobago are a seafloor terrain marked by scattered mud volcanoes, mud walls, and mud canopies that rise several hundred meters above the modern seafloor. We use 3D seismic and recently drilled wells to examine this area, dividing it into three tectonomorphic provinces based on the nature of the mud architecture, the structuration, basin types developed, and sedimentary systems occupying the basins. Mud architectures become more massive as one moves northward toward the active tectonic prism. The mud wall in the far northern Mud Wall Province is classified as a mud canopy system, similar to those documented by workers in the North Sabah Pagasa Wedge, Borneo. The Trinidad mud canopy exhibits sutures in the mud mass margins (akin to salt sutures) that separate submasses likely composed of different materials and exhibiting different pressures and properties. These submasses and associated sutures are imageable using the sweetness attributes on the near-stack seismic volume. Anticlines in the isolated mud and distributive provinces, similar to those that are the dominant hydrocarbon-producing structures onshore and offshore Trinidad, show mobile mud cores and are associated with extensional and compressional faulting that provide pathways for hydrocarbon migration into the surrounding lutokinetic stratigraphy. A bottom simulating reflector associated with the base of the gas hydrate zone, extensive across the study area, may be a good indicator of fluid flux activity and subsurface pressure states in mud masses. It is important to use all the seismic data volumes (full, near, mid, and far seismic data stacks) to assess different aspects of these mud diapiric systems.