Composition of the core from gallium metal-silicate partitioning experiments

摘要: Gallium concentration (normalized to CI chondrites) in the mantle is at same level as that of lithophile elements with similar volatility, implying there must be little no gallium Earth's core. Metal-silicate partitioning experiments, however, have shown a moderately siderophile element and should therefore depleted by core formation. Moreover, concentrations (4 ppm) are too high only brought late veneer; neither pressure, nor temperature, silicate composition has large enough effect on make it lithophile. We systematically investigated (light content) carrying out metal-silicate experiments piston-cylinder press 2 GPa between 1673 K 2073 K. Four light (Si, O, S, C) were considered, their was found sufficiently strong The then modeled parameterized function redox composition. A continuous formation model used track evolution during formation, for various magma ocean depths, geotherms, contents, (redox) accretion. which final Earth matched observed value one involving light-element rich equilibrating FeO-rich deep (>1300 km) pressure least 50. GPa. More specifically, incorporation S C provided successful models lie far beyond allowable cosmochemical or geophysical limits, whereas realistic 0 Si amounts (less than 5 wt.%) oceans deeper 1300 km. These results offer argument an O- Si-rich core, formed terrestrial ocean, along oxidizing conditions. (C) 2015 Elsevier B.V. All rights reserved.