Earth's Core Formation and Composition : New Constraints from Diamond Anvil Cell Experiments
Abstract
The pattern of siderophile (iron-loving) element abundance in the silicate portion of the Earth is a consequence of metal separation during core formation. Thermodynamic expressions used to constrain the metal-silicate partitioning behavior of siderophile elements are mainly established from large volume press experiments that do not cover the full range of potential P-T conditions for core-mantle equilibrium. The diamond anvil cell is the only static technique capable of achieving required P-T conditions but until now its capabilities to perform quantitative metal-silicate partitioning experiments at extreme conditions has been untapped. We use protocols that effectively link high P-T diamond anvil cell with analytical techniques such as focused ion beam device (FIB); NanoSIMS; electron microprobe; transmission electron microscopes; and in-situ synchrotron X-ray diffraction measurements allow us to obtain quantitative data on element partitioning at superliquidus conditions above 30 GPa and 3000 K. Here we present our advances in both experimental and analytical methods. We look at the partitioning of 6 siderophile elements (Ni, Co, Cr, V, Mn, and Nb) that have been extensively studied at lower P-T conditions and constrain the solubility of light elements (Si and O) at these extreme conditions. We then update expressions that describe the partitioning behavior of these elements to address the validity of proposed core formation models (i.e. single-stage core formation model and continuous core formation model).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMMR51B2179S
- Keywords:
-
- 1015 GEOCHEMISTRY / Composition of the core;
- 3612 MINERALOGY AND PETROLOGY / Reactions and phase equilibria;
- 3630 MINERALOGY AND PETROLOGY / Experimental mineralogy and petrology