[SCG57-06] Thermal conductivity under high-pressure conditions of core samples from IODP NanTroSEIZE input site C0012
Keywords:NanTroSEIZE, Thermal Conductivity, High-Pressure
The in-situ thermal conductivity of sediments in a deep part of the accretionary prism of the seismogenic zone may mainly depend on the solid grain components and in-situ porosity of the sediments. Based on this consideration, we have conducted laboratory experimental study aimed to figure out quantitative relationship between thermal conductivity of core samples and their porosity. For the experiments, we must use the core samples with the same/similar solid grain components as those from the great depths. Because sediments from sedimentary formations overlaying the in-coming subducting oceanic basement will subduct in the accretionary prism, they may have the same/similar solid grain components. Therefore, we collected whole-round sediment core samples retrieved from sedimentary formations at the NanTroSEIZE input site C0012; and then measured their thermal conductivity change with increasing confining pressure, i.e., to change the core samples’ porosity to simulate the subduction process. We have successfully measured the thermal conductivities of six core samples from a depth range from ~144 to ~ 518 meters below seafloor at IODP site C0012 under high pressure conditions up to a maximum effective pressure of ~50 MPa. Consequently, an empirical equation between thermal conductivity and porosity for the Nankai Trough accretionary prism was obtained. The equation enables us to estimate thermal conductivity from in-situ porosity estimated from log data.