High Pressure Study on Siderophile Volatile Element Metal-Silicate Sulfide-Silicate Partitioning.

The question when and how volatile elements were delivered to Earth is subject to intense debate [1 - 7]. Understanding the partitioning behavior of volatile elements that are also siderophile and/or chalcophile (S, Se, Te, Tl, Ag, Au, Cd, Bi, Pb, Sn, Cu, Ge, and In) may provide key information in this regard. This project aims to unravel whether the depletion of the siderophile volatile elements (SVE) in Earth's mantle is a core formation signature [7 - 10], a volatilization signature or related to a late accretion after core-mantle differentiation had largely ceased [2 - 3].

A special interest is laid into chalcophile element (Cd, Pb, Bi, Se, Te, S) behavior with respect to the possible formation and late segregation of a "Hadean Matte" [9].

To examine the influence of sulfur on SVE partitioning between metal- and silicate- melts, we performed experiments from sulfur free to sulfur rich-melts ( 35 wt% S). Partitioning experiments were carried out under various P-T-fO₂ conditions with a 600 t walker-type multi-anvil press (7-10 GPa, 1700-2100 °C). The run products were analyzed via EMPA and LA-ICP-MS. Preliminary results show various effects of sulfur on our focused chalcophile element metal-silicate, sulfide-silicate partitioning behavior. Disparities can be seen between Te, Se Cd and Pb respectively. Although showing similar volatility [11, 12] Se partitions less strongly into metal than Te. Cd, and Pb however show lower metal-silicate partitioning coefficients than Se and anomalies like this makes it difficult to explain a "Hadean Matte" effect.

References: [1] Albarède F. (2009) Nature, 461, 1227-1233. [2] Ballhaus C. et al. (2013) EPSL, 362, 237-245. [3] Ballhaus C. et al. (2017) CMB, 172, 1-10. [4] Fischer-Gödde M. and Kleine T. (2017) Nature, 541, 525 527. [5] Wade J. and Wood B. J. (2005) EPSL, 236, 78-95. [6] Norris C. A. and Wood B. J. (2017) Nature, 549, 507-510. [7] Rubie D. et al. (2016) Science, 253, 1141-1144. [8] Boujibar et al. (2014) EPSL, 391, 42-54. [9] O'Neill H. St. C. (1991) GCA, 55, 1159-1172. [10] Rubie D. et al. (2011) EPSL, 301, 31-42. [11] Lodders et al. 2003 TAJ, 591, 1220-1247. [12] Palme H., O'Neill H. St. C. 2003, TG, 1-35.