The δ18O of primary and secondary waters in hydrous volcanic glass

Abstract

Abstract We present analyses of phyllosilicates, volcanic glass, and a series of experiments and observations on the δ18O of water extracted by rapid thermal pyrolysis at 1450\u202f°C using the TCEA (Thermal Conversion Elemental Analyzer). The study includes the same hydrous glasses that were previously analyzed for their δD values of extracted water (Seligman et al., 2016). We utilize natural phyllosilicates (where water is present as OH– only), natural magmatic and experimentally quenched glasses, (in which water occurs as H2Om and OH−), and glasses that underwent low-temperature secondary hydration by meteoric water (almost completely as H2Om). Our study documents that: 1) thermal extraction and simultaneous pyrolysis of H2Ot into CO and H2 produces little or no exchange (