4:15 PM - 4:30 PM
[SGL29-09] Thermal fluid migration in the Kumano forearc basin, Nankai Trough, estimated via vitrinite reflectance measurement
Keywords:Nankai Trough Seismogenic Zone Experiment as part of the Integrated Ocean Drilling Program (IODP NanTroSEIZE), Kumano forearc basin, Vitrinite reflectance measurement, Paleo-thermal structure
The thermal fluid upwelling could relate to thrusts and ancient splay fault activity near Site C0009. The thermal anomaly zone in the Kumano forearc basin at Site C0009 coincides with the currently fluid conduit zone. Fluid rich zones have been identified close to as well as seaward and landward of Site C0009 using seismic reflection and velocity data and geochemical data from deeply sourced mud volcanoes. Tsuji et al. (2015) and Nishio et al. (2015) also argued that the fluids migrated along active and/or inactive fault zones, possibly the connected to the plate boundary. These results suggest that, although the landward portion of the accretionary prism appears to be inactive with respect to seismic slip, inactive structures play a significant role in fluid and heat transport within the prism. Furthermore our results indicate that massive fluid circulation occurs spatially and temporally through thrusts in the subduction zone.