Cl stable isotopes in subduction zones: Implications for the ocean Cl isotope cycle

Document Type

Conference Proceeding

Date of Original Version



Chlorine stable isotope ratios (δ 37Cl) in pore fluids, serpentines, and solid samples from three subduction zones, the Nankai Trough (Ocean Drilling Program Legs 131 and 190), Costa Rica (ODP Legs 170 and 205), and Mariana Forearc (ODP Leg 195) provide critical information on fluid sources, flow paths, and reaction conditions at subduction zones. The δ 37Cl values of pore fluids at the Nankai and Costa Rica subduction zones are significantly more negative (up to -7.8‰, 2σ ±0.3‰) than the seawater value (0‰). In contrast, the δ 37Cl values in the pore fluids at the Mariana mud volcanoes range from+0.3‰ to +1.8‰, which, together with ridge crest hydrothermal fluids, having δ 37Cl up to 4.1‰, constitute positive 37Cl fluxes into the ocean that compensate the negative δ 37Cl fluid fluxes at subduction zones. © 2007 Taylor & Francis Group, London.

Publication Title, e.g., Journal

Water-Rock Interaction - Proceedings of the 12th International Symposium on Water-Rock Interaction, WRI-12