Effect of Oxidation on the VNIR Spectra of Olivine

The crust of Venus is composed mostly of basaltic rock, which is in contact with its hot caustic atmosphere [1, 2]. Chemical reactions between Venus’ basaltic crust and its atmosphere, ‘weathering,’ modify the surface’s mineralogy and composition [3], which results in changes in their spectral characteristics and radar backscatter [4]. Without liquid water, weathering should be slow and mainly produce coatings on surfaces of grains and rocks [1, 3]. However, the chemical products and rates of basalt weathering on Venus and how these affect Visible-Near Infrared (VNIR) reflectance spectra are not well constrained. Here we present new VNIR reflectance data for olivine experimentally altered and oxidized in contact with the terrestrial atmosphere at 600° C and 900° C. These results constrain the rate at which olivine grains become coated with oxidation minerals, how the effects of surface coatings affect VNIR spectra, and how Venus may appear in the VNIR.

Authors: J. Filiberto, D. Trang, A.H. Treiman, and M.S. Gilmore

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