Cadmium, indium, tin, tellurium, and sulfur in oceanic basalts: Implications for chalcophile element fractionation in the Earth

Concentrations of S, Cd, In, Sn, and Te are reported for 80 samples of mido cean ridge basalt (MORB), submarine and subaerial ocean island basalt (OIB) and submarine are lavas. Cadmium, In, and Sn are moderately incompatible, and Te is compatible during partial melting. Cadmium is particularly unifor m, consistent with a homogeneous distribution in the mantle. Tellurium is m ore variable (1-6 ppb) and is notably higher in Loihi, ranging up to 29 ppb , the most likely explanation for which is accumulation of Cu-bearing sulfi de. The average Cd/Dy ratio is the same (0.027) for OIB glasses, MORB glass es and the continental crust, yielding a primitive mantle Cd concentration of similar to 18 ppb. Indium, despite being more volatile, is less depleted than Cd and the other very volatile chalcophile elements Pb, Bi, Tl, and H g. From the depletion of In we deduce that core formation depleted the sili cate Earth in Cd, ph, Bi, Tl, and Hg by between factors of 5 and 10. The In depletion yields concentrations of C, S, Se, and Te in the core of C simil ar to 1.2%, S > 2.4%, Se > 7.1 ppm, and Te > 0.89 ppm. The Moon appears to be enriched in Te relative to the silicate Earth. Either a significant frac tion of the Moon was derived from a more Te-rich body or the silicate Earth 's inventory of chalcophile and siderophile elements was depleted by furthe r terrestrial core growth after formation of the Moon.