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Planetesimals in the early solar system underwent thermal processing from short-lived radioactive isotope decay that led to varying degrees of metamorphism, partial melting and/or magma ocean formation. Accretion of planetesimals led to the formation of the planets including the Earth with all its oceans of water. While planetesimals may have lost their water contents prior to the onset of melting, it remains unclear whether water loss can be tracked during different stages of thermal metamorphism. In this study, we performed secondary ion mass spectrometry on nominally anhydrous minerals (NAMs) from a suite of ordinary chondrite meteorites that experienced varying degrees of thermal metamorphism. Our measurements of H abundances quantified as (µg/g H2O) indicate that NAMs are efficiently dried out by the onset of metamorphic re-equilibration of silicate phases. Furthermore, preliminary analyses from unequilibrated ordinary chondrites show that NAMs in these meteorites likely do not start off with much water even prior to thermal metamorphism. NAMs constitute over three-fourths of ordinary chondrite meteorites by volume. Therefore, it seems probable that the Earth requires delivery of water through the accretion of small amounts of water-rich primitive meteoritic material from the outer solar system. |