Abstract:
The Caribbean Plate subducts beneath the North American Plate at the Muertos Trough and beneath the South American Plate at the South Caribbean deformed belt (SCDB). During a subduction, large amount of sediments enter the subduction zone with the down going plate, and some crustal material may be incorporated into the accretionary prisms. To investigate the changes in collisional style and structures associated with subduction of the Caribbean Large Igneous Province (CLIP) versus normal oceanic crust, we interpret seismic reflection profiles collected around the Muertos Trough and SCDB, including those collected in the Venezuelan Basin. We determine the extent of the CLIP in the eastern region of the Caribbean Plate by identifying the structural differences at the top of the basement (Horizon B') on a dataset of 150 multi-channel seismic marine reflection profiles acquired during eight cruises between 1975 and 2004, as well as selected Integrated Ocean Drilling Program (IODP) drilling data. We also analyze the profiles for presence of sedimentary material in the trench and in the subduction channel in order to determine whether the material is recycled back into the mantle, and to characterize the northern and southern subduction zones as accretionary or erosive. Our preliminary results are that the CLIP extends across most of the Venezuelan Basin, the western part of the Columbian Basin, and the Beata Ridge. Furthermore, some portions of the CLIP at the northern and southern boundaries subducts beneath the North and the South American Plates at the Muertos Trough and the SCDB, respectively. The change in nature of the subducting plate (CLIP or normal oceanic crust) causes variations in the collision style (i.e., accretionary versus erosive) and in structures at the accretionary wedge and on the downgoing plate.