NanoSIMS analyses of apatite and melt inclusions in the GRV 020090 Martian meteorite: Hydrogen isotope evidence for recent past underground hydrothermal activity on Mars

The analyses of apatite show a distinct positive correlation between the water contents (0.10-0.58 wt%) and the δD values (737-4239‰), which can be explained by assimilation of D-rich Martian crustal materials and enhancement of water via fractional crystallization. The observed correlation suggests that the water contents of Martian mantle reservoirs might have been overestimated from D-enriched apatite in previous studies. Our estimation based on the least contaminated apatite grains from GRV 020090 turned out a low water content of the primordial parent magma (380-750 ppm), which was likely derived from a relatively dry Martian mantle reservoir of GRV 020090 (∼38-75 ppm H2O).