GEO 330 Lecture Notes - Lecture 20: Goldschmidt Classification, Radiogenic Nuclide, Olivine
31 Mar 2018
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Document Summary
Snc meteorite chemistry used to estimate composition of silicate portion of mars (mantle and crust) Details vary between models, but they agree on main aspects of mantle chemistry. Preferred model of driebus and wanke estimated key ratios of siderophile, chalcophile, and volatile elements in crust and mantle, and then assuming ci chondrite abundances for refractory elements. Initial studies concluded that snc source regions and terrestrial mantle are chemically similar. Mars has more oxidized fe, implying martian mantle is denser at equivalent pressures than terrestrial mantle. Mars has higher abundances of moderately volatile elements, suggesting that it accreted with more volatiles. Mars has lower abundances of siderophile elements with strong chalcophile affinities (co, ni, cu) Mars has higher abundances of siderophile elements with weak chalcophile affinities (mn, cr, w) Could be indicative of higher oxidation state of mars, as mantle retained more feo and other siderophiles during core formation. Fes would separate during core formation and leave behind weakly chalcophile elements.
