Identifying clinopyroxene-sulphide co-precipitation, rejuvenation mechanisms and platinum-group element fractionation processes in young continental mantle roots

• Applicant: Professor Dr. Reiner Klemd
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2010 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 193144490

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) techniques shall be utilized to investigate platinum-group elements (PGE) systematics of sulphides in young subcontinental lithospheric mantle (SCLM). We aim at providing a siderophile perspective on continental lithosphere rejuvenation: a process of pyroxene introduction at the expense of olivine. This rejuvenation has been proposed to operate within the compositional range anticipated for mildly depleted peridotite and appears to be more relevant than previously anticipated. However, this rejuvenation concept does not address the evolution of siderophile minerals and thus the PGE content of such continental mantle roots. By analyzing the sulphide fraction for the PGE content using LAICP- MS from a suite of well-characterized Middle Atlas peridotite xenoliths with unusually well correlated whole-rock PGE, Cu and major element systematics that has experienced modal rejuvenation we will be able to (a) characterize the sulphide mineralogy responsible for the whole rock PGE composition, (b) identify coupled or decoupled sulphide-silicate and –oxide precipitation and consumption during metasomatism and (c) study the potential for PGE fractionation in sulphides from SCLM. This data acquisition will be unique for peridotites from off-cratonic continental mantle roots and thus will allow further conclusion on the mobility of economically relevant elements during magmatic processes and the secular dichotomy of PGE systematics in the lithospheric mantle.

• DFG Programme: Research Grants
• Participating Person: Dr. Nadine Wittig