ACCRETION AND CORE FORMATION ON MARS - MOLYBDENUM CONTENTS OF MELT INCLUSION GLASSES IN 3 SNC METEORITES

Molybdenum, cerium, barium, yttrium, and rubidium contents of glasses in melt inclusions in three SNC meteorites (LEW 88516, Governador Vala dares, 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 primi tive Martian mantle, 120 +/- 60 ppb. Abundances of five moderately sid erophile elements (Ni, Co, Mo, W, and P) and Re in the Martian mantle are consistent with metal-silicate equilibrium between S-bearing metal lic liquid tin a core 22 wt% of the planet) and peridotite melt at 75 kb, 1620 degrees C, and oxygen fugacity 1.1 logfO(2) units below the T W buffer. This homogeneous accretion scenario is different than many h eterogeneous accretion models for the Earth, but similar to recent stu dies suggesting homogeneous accretion in the presence of a deep terres trial magma ocean. Copyright (C) 1998 Elsevier Science Ltd.