The Contrast in Outgassing of Germanium Between Shergottites and Nakhlites

Yang, S ; Humayun, M ; Righter, K ; Peslier, A H

关键词: OUTGASSING;    GERMANIUM;    SHERGOTTITES;    NAKHLITES;    MARS SURFACE;    METEORITES;    IGNEOUS ROCKS;    FRACTIONATION;    SOILS;    LASER ABLATION;    ABUNDANCE;    MINERALS;    SIDEROPHILE ELEMENTS;    ISOTOPES;    MAGMA;    IN SITU MEASUREMENT;   

RP-ID  :  JSC-E-DAA-TN51569

学科分类：天文学(综合)

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

Final Paper and not the abstract is attached. Introduction: Germanium is generally thought to follow Si in its geochemical behavior, but little data has existed to rigorously understand the behavior of Ge in the Martian mantle. Germanium is known to be more siderophile than Si, and its partitioning into the martian core has been studied by. Typical abundances in igneous martian meteorites range from 0.5-3 ppm, a larger range than what is observed in terrestrial basalts (1.5 +/- 0.1 ppm). In situ measurements by the MER and MSL rovers have revealed a surprisingly large range in Ge abundances in surface rocks (30-650 ppm), but many igneous rocks and soils are shown to have greater than 30 ppm Ge (the detection limit of the APXS). Recently, reported that shergottite minerals showed a depletion of Ge with increasing fractionation, while nakhlites and chassignites exhibited Ge behavior compatible with closed system igneous differentiation. They interpreted their observations as tentatively indicating volcanic outgassing of Ge from shergottites (but not from nakhlite-chassignites) with recondensation of the Ge vapor into soils and breccias. Recent experimental studies show that Ge is significantly volatile from magmas. In this study, we followed up on those results by analyzing minerals in five nakhlites and five shergottites by laser ablation ICP-MS (LA-ICP-MS). See Attached