Synopsis: The oxygen fugacity of the basaltic martian meteorites has been calculated from thermodynamic models involving spinel-ilmenite equilibria. The wide range of estimates, from near the IW buffer to near QFM, may be explained by mixing of mantlederived melts with oxidized material in the martian crust. Possible oxidized crustal end-members are considered. Analytical Method and Results: Sp...

..................................................................................................................... iii ACKNOWLEDGEMENTS ............................................................................................... iv LIST OF FIGURES .......................................................................................................... vii LIST OF TABLES ....................

INTRODUCTION Several studies have demonstrated the usefulness of Synchrotron micro x-ray absorption near edge structure (XANES), or (SmX) spectroscopy, to determine the oxidation state of elements in planetary materials. Delaney et al. [1] used SmX to investigate the oxidation states Fe, Cr, and V in extraterrestrial samples, and later determined the oxidation state of V in experimental glasses...

and the chemical weathering of primary minerals to secondary minerals (i.e., soil) on the surface. Physical properWe present a comprehensive study of the redox state of the lower atmosphere and surface of Venus. This study constrains ties such as the spectral reflectance, dielectric constant, the CO concentration and oxygen fugacity at the surface of electrical conductivity, magnetic susceptibi...

Understanding of the geochemistry of the chalcophile elements [i.e., Os, Ir, Ru, Pt, Pd (platinum-group elements), and Au, Cu, Ni] has been informed for at least 20 years by the common assumption that when crust-forming partial melts are extracted from the upper mantle, sulfide liquid in the restite sequesters chalcophile elements until the extent of partial melting exceeds approximately 25% an...

Introduction: The partitioning of oxygen between silicates and liquid Fe-rich metallic alloy is a key factor in controlling chemical differentiation during core formation in terrestrial planets [1]. This is because oxygen partitioning determines the oxygen fugacity uniquely for a given bulk composition and therefore controls the partitioning of Fe and other siderophile elements during core form...

Sulfur is a key element in terrestrial magmatic processes yet its geochemical behavior remains one of the most difficult to model due heterovalent chemistry. The maximum amount sulfur silicate melt can dissolve before saturating with sulfide (e.g., pyrrhotite) or sulfate anhydrite) changes redox state system and has important implications for budget system. Several empirical models have been de...

The basic aspects of redox geochemistry are reviewed to provide a useful compendium the connection between aqueous-hydrothermal and igneous realms Earth. description system is intimately coupled knowledge acid-base properties solvent in which exchanges take place. For magmas, then silicate melts, approaches reporting state were so far cantered around sole concept oxygen fugacity, f O 2 . Master...