Caiwei Guyot Eastern Manus Basin Kueishantao hydrothermal field Li-O-Mg isotopes Okinawa Trough Tianxiu Vent Field Yonaguni Knoll IV hydrothermal field alkaline digestion anglesite apatite dacite detachment fault detrital zircon diffusion chronometry element distribution and mobility element enrichment ferromanganese crust ferromanganese nodule fluorine and chlorine geochemistry high pressure bomb hydrothermal plume hydrothermal resources hydrothermal vent in-situ chemical and isotopic compositions ion chromatography magma magma eruption magma evolution magma mixing