Dewatering through mud mounds on the continental fore-arc of Costa Rica
This work studies the contribution and significance of mud mounds in the dewatering of the continental fore-arc in an erosive subduction system. Through the analysis of multibeam bathymetric, narrow-beam sediment echosounder, and multi-channel seismic data, the main goals are to determine the structure and mechanism of mud domes investigated at two study areas, and to identify and locate alternative fluid pathways through the subsurface. Structural investigations near a single large mound reveal it to be of diapiric origin. Based on the observed deformation and sediment deposition patterns in its vicinity, a local tectonic model of the Mound Culebra area is constructed. Thermal modelling in the area, allowed by a widespread presence of clathrates in the subsurface, helps identify probable locations of heat and fluid advection as well as evaluate their relative importance. These results are compared to those from a second study area, the differences revealing a significant effect of subducting seafloor topography on the deformation and dewatering patterns of the fore-arc. A possible fate of mud mounds on the Central American margin is also outlined.