4:45 PM - 5:00 PM
[SIT22-24] U and Th abundances of crustal rocks in the Japan Arc: Towards better constraints on the geoneutrino flux from the mantle
Keywords:neutrino, chondritic Earth, bulk silicate Earth
For better understanding of U-Th distributions in the Japan Arc, we have compiled previously reported U-Th abundance data for crustal rocks in the Japan Arc and further conducted petrology and geochemistry on mafic-ultramafic xenoliths from Oki Dogo. The equilibrium temperatures of two-pyroxenes indicate their derivation from the depth of 25-35 km. By combining the compiled data and newly obtained data, we found that the relative abundances of U and Th of the Japanese deep crust are distinctive from those of the deep crust in cratonic regions. The discrepancy may reflect that the Japan Arc crust was formed under more oxidized conditions as compared to the cratonic deep crust. In the presentation, we will further discuss about a methodology for combining these rock data with seismic data to estimate the U and Th distributions within the deep crust over the wide area.