• journal_title：American Mineralogist
• Contributor：Jim M. Karner ; Steven R. Sutton ; James J. Papike ; Charles K. Shearer ; John H. Jones ; Matt Newville
• Publisher：Mineralogical Society of America
• Date：2006-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2006.1830
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：91
• issue：2-3
• firstpage：270
• section：Articles

The redox states of volcanic and impact melts from the Earth, Moon, and Mars have been estimated from the valence state of V in basaltic glasses (Sutton et al. 2005). The V valence has been determined using synchrotron micro X-ray absorption near-edge structure spectroscopy (XANES) (Sutton et al. 2005), which allows for in situ measurements on samples with a micrometer spatial resolution and ~100 ppm elemental sensitivity. Here, we interpret those results for the natural samples and compare them to the literature. The results show that terrestrial melts are dominated by V⁴⁺, lunar samples by V³⁺, with Martian melts a mixture of both V³⁺ and V⁴⁺. The f_O2 estimates derived from the V valence are consistent with those determined by other proven methods, whereby terrestrial basalts experience f_O2 conditions within 1 or 2 log units of the QFM buffer, lunar basalts equilibrate at 1 to 2 log units below the IW buffer, and Martian basalts fall somewhere between the QFM and IW buffer. The results illustrate the usefulness of this technique; i.e., a robust oxybarometer covering over six orders of magnitude, applicable to samples that record f_O2 conditions from reduced extraterrestrial bodies to the oxidized Earth.