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[SRD41-04] Li isotopic composition of submarine vent fluids from arc and back-arc hydrothermal systems in the western Pacific
Keywords:submarine hydrothermal system, lithium isotope ratio, vent fluid, arc, back-arc basin
Based on mass balance calculation, Li in vent fluids are dominated by seawater-rock (seawater-sediment) interaction in sediment-starved (sediment-hosted) hydrothermal systems in arc and back-arc basins at equilibrium. Li contents in vent fluids is also influenced by phase-separated processes, by temperature-related portioning of rock Li into fluid phase, and by host rocks and sediments. In contrast, Li isotopic composition in vent fluids is affected by host rocks and sediments, but not by phase-separated processes. These results demonstrate that lithium is a useful tracer for investigating geological processes occurred underground such as a phase separation process and water-rock/water-sediment interaction at high temperature.