Accretion and core formation on Mars: molybdenum contents of melt inclusion glasses in three SNC meteorites

Molybdenum, cerium, barium, yttrium, and rubidium contents of glasses in melt inclusions in three SNC meteorites (LEW 88516, Governador Valadares, and Chassigny) have been measured by ion microprobe. Ratios of Mo/Ba and Mo/Ce have been used to estimate the Mo content of the primitive Martian mantle, 120 ± 60 ppb. Abundances of five moderately siderophile elements (Ni, Co, Mo, W, and P) and Re in the Martian mantle are consistent with metal-silicate equilibrium between S-bearing metallic liquid (in a core 22 wt% of the planet) and peridotite melt at 75 kb, 1620°C, and oxygen fugacity 1.4 log fO 2 units below the IW buffer. This homogeneous accretion scenario is different than many heterogeneous accretion models for the Earth, but similar to recent studies suggesting homogeneous accretion in the presence of a deep terrestrial magma ocean.