NASA NTRS2012
Volatile siderophile elements (e.g., As, Sb, Ge, Ga, In, Bi, Zn, Cd, Sn, Cu, Pb) can place constraints both on early differentiation as well as the origin of volatiles. This large group of elements has been used to constrain Earth accretion [1,2], and Earth-Moon geochemistry [3]. Application to Earth has been fostered by new experimental studies of these elements such as Ge, In, and Ga [4,5,6]. Application to Mars has been limited by the lack of data for many of these elements on martian meteorites. Many volatile elements are considered in the pioneering work by [7] but for only the small number of martian samples then available. We have made new measurements on a variety of martian meteorites in order to obtain more substantial datasets for these elements using the analytical approach of [8]. We use the new dataset, together with published data from the literature, to define martian mantle abundances of volatile siderophile elements. Then, we evaluate the possibility that these abundances could have been set by mid-mantle (14 GPa, 2100 C) metal-silicate equilibrium, as suggested by the moderately and slightly siderophile elements [9]. Finally, we examine the possibility that some elements were affected by volatility and magmatic degassing.