Platinum-group elements and the multistage metasomatic history of Kerguelen lithospheric mantle (South Indian Ocean)
- Lorand, Jean-Pierre
- Delpech, Guillaume
- Gregoire, Michel
- Moine, Bertrand
- O'Reilly, Suzanne Y
- Cottin, Jean-Yves
DOIAbstract
Chalcophile and highly siderophile trace elements in Kerguelen mantle xenoliths monitor a multistage melt-depletion/metasomatic history in the lithospheric mantle. A high-degree partial melting event in a fast-spreading oceanic ridge setting generated protogranular harzburgites strongly depleted in S (<5 ppm), Se (<7 ppb), Cu (<5.1 ppm) and Pd (Pd/IrN<0.2; N=CI-chondrite normalised). This refractory protolith was subsequently percolated in a within-plate setting by large fractions of basaltic to highly alkaline melts, which produced poikiloblastic harzburgites. Their PGE concentrations (including the IPGE; Os, Ir, Ru) are depleted by factors of 2 to 5 (0.002–0.005×CI-chondrites) compared with those of the protogranular harzburgites. Spinel ...
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