Comparison Between Bidirectional and Hemispherical Spectra of Venus-Analog Basalt-Weathering Product Mixtures

Kurzfassung

Chemical weathering on Venus is predicted to happen solely through oxidation and sulfurization as exposed rocks interact with the CO2- and S-rich atmosphere, with negligible hydration or physical weathering due to the lack of surface water or eolian processing. Experiments on Venus-analog basalts under CO2 and CO2+S atmospheric conditions have shown that common weathering products are Fe- oxides and sulfates [1,2]. The specific mineral species expected are dependent on the composition of the underlying basalt. Tholeiitic basalts weather to anhydrite (CaSO4) and an Fe-oxide, likely magnetite, and high-Na alkaline basalts weather to thenardite (Na2SO4) and an Fe-oxide, likely magnetite [1,2]. The oxidation state of the near-surface atmosphere (fO2= 10- 20 – 10-21.7) suggests that magnetite reacts with the CO2 atmosphere, oxidizing to hematite [3,4,5]. Chemical weathering on the surface of Venus has yet to be confirmed but has potentially been observed [6].