Redox in Impact Melt Bodies from Fe-XANES and Implications for Outgassing
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Dr. Ben Black
Assistant Professor
City University of New York
Redox in Impact Melt Bodies from Fe-XANES and Implications for Outgassing
Impact melting was a widespread process in the early solar system. The redox state of silicate magmas controls the speciation of volatile elements dissolved in a magma and major elements such as iron, and consequently influences the composition of gases released to the atmosphere. How do the extreme pressure-temperature conditions of impacts, and interactions between target rock, impactor, and atmosphere, influence the redox of impact melts? Here we present Fe-XANES measurements of Lonar crater impact melt glasses. The Fe-XANES technique permits robust characterization of the Fe3+/Fe2+ ratio in basaltic glasses. This ratio, in turn, directly reflects redox. As Earth’s only known impact into continental flood basalts, Lonar crater is an ideal analog for impacts into basalt targets as expected for most impacts early in the history of Earth and Mars. Our results demonstrate the potential range in impact melt redox even for homogeneous target rocks, implying that gases released from impact melts may differ substantially from volcanic gases.
Host: Dr. Michael Sori