[SGC45-P01] Hydrogen isotope study of serpentinite from the Happo-O'ne area: Implications for the water cycle in subduction zone
Keywords:Serpentinite, Hydrogen isotopes, Happo-O'ne
The dD values of serpentinite ranges between −135‰ and −47‰. Considering equilibrium isotopic fractionation between serpentine and water (Saccocia et al., 2009), at the formation temperature of Antigorite, these serpentinite rocks are clearly not originated from modern seawater (0‰). Serpentinites having lower dD (c. −125‰) is rather derived from meteoric water in this area (dD = −90‰; Suda et al., 2014). This is consistent with the geology: serpentinite having lower dD is mainly associated with talc, which was contact metamorphosed by intrusive granite. On the other hand, dD value of the water which was equilibrated with serpentinite having higher dD values, intermediate between seawater and present day meteoric water. These serpentinite rocks are relatively away from the granite intrusion and may still preserve pristine information of water in the mantle wedge. If so, our results imply intensive dehydration from subduction slab.
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