Collaborative Research: Cl-isotope systematics of back-arc spreading systems: Insights into geochemical cycling of volatile elements between crust, hydrosphere and mantle

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This research supports researches at two institutions: WHOI in Massachusetts and Oregon State University. The work involves the development of techniques and protocols to analyze a promising new tracer (chlorine stable isotopes) of volcanic volatiles in subduction zone volcanic rocks on a secondary ion mass spectrometer. Chlorine stable isotopes are suspected to be important tracers of volcanic fluids and this study examines this possibility using samples from a variety of volcanic glasses. The research program includes the identification of matrix and other effects in the samples that can compromise analytical precision and accuracy of the method and analyzes a suite of twelve samples that have also been measured and calibrated on thermal ionization mass spectrometers. This duplication allows a quantitative determination of the accuracy and precision of this new in-situ technique and a comparison with results obtained by standard mass spectrometry to assess the level of confidence that can be placed on these analyses. Additional samples, that include glasses in melt inclusions trapped in crystals from volcanic rocks from back arc spreading centers in the Lau Basin in the western Pacific Ocean, will also be examined. The analyses represent the first time in-situ analyses have been made on melt inclusions in volcanic glasses.Broader ImpactsBroader impacts of this work are to develop new techniques and protocols to permit the analysis of chlorine stable isotopes on a secondary ion mass spectrometer. It will also support analytical infrastructure at WHOI as well as foster collaboration between two universities in the US and the NORDSIM analytical facility in Stockholm, Sweden.