9:30 AM - 9:45 AM
[SCG56-03] Central Japan as a cold subduction zone revisited: implications for deep dehydration beneath the Noto peninsula
Keywords:Japan arc, Central Japan, subduction, dehydration, fluid, Noto peninsula
In this presentation, we re-examine the regional distribution of geochemical composition of the erupted lavas over the Japan arc and characterize the magma generation conditions and its spatial (particularly along-arc) variation, through which the physico-chemical condition beneath Central Japan is highlighted. We first utilize the isotopic compositions (Sr-Nd-Pb isotopic ratios) of lavas and statistically analyze them to clarify the geographical provenance. Then we incorporate trace element compositions to discuss source mantle characters, fluid regimes, and degree of partial melting. The results confirm the cold environment beneath Central Japan and suggest a deep dehydration at ~300 km depth from the subducted slab without causing melting above the deep dehydration region, such as the Noto peninsula. The deep dehydration with no melting may account for the earthquake swarm and crustal deformation that suggest a supply of large amount of deep-seated fluid beneath the peninsula (e.g., Nishimura et al., 2022).