Tuesday, 28 August 2007
2.PS-37
Platinumgroup elements in sills of the Jurassic Ferrar Large Igneous Province from northern Victorialand, Antarctica
Ricarda Hanemann and Lothar Viereck-Goette. Institut fuer Geowissenschaften, Friedrich-Schiller-Universitaet Jena, Burgweg 11, 07747 Jena, Germany
Platinum group element (PGE) abundances were analyzed in basaltic andesites and andesites from sills of the Ferrar Large Igneous Province (FLIP) from northern Victoria Land. The strongly fractionated primitive mantle-normalised PGE-patterns show enrichment of the Pt-PGE over the Ir-PGE. The single element abundances exhibit good correlations with the degree of differentiation of the distinctly evolved samples and are interpreted to result mainly from low-pressure in-situ differentiation after upper-crustal magma emplacement. Compared to tholeiitic rocks from other magmatic provinces, only the FLIP rocks exhibit coupled enrichment of Pd, Pt and Cu even in most evolved samples. The decrease of Pt and Pd in some of the more evolved samples does not necessarily signify sulphide fractionation, but may indicate the formation of other PGE-compounds. The inferred sulphur-undersaturated conditions during differentiation are in agreement with the elevated melting degrees as well as the refractory nature of the proposed subcontinental lithospheric mantle source.