[BPT05-P09] Hydrogen Isotopic Composition of Archean Seafloor Basalts & Gabbros
Keywords:Hydrogen isotpe, Archean, Earth's History
Our results show a clear correlation between metamorphic facies in hydrated ocean-floor minerals and H and O isotopic compositions. The measured δD values are positively correlated with δ18O values and H2O content in response to metamorphic grade. By analogy with moden seafloor basalts, the correlation beween δD and H2O content implies seafloot basalt hydrothermal alteration and dehydration with metamorphism. From this hypothesis, we estimate that seawater at 3.2 Ga was depleted in deuterium by about 20‰ compared to modern seawater.