Open System Re-Os Isotope Behavior in Platinum-Group Minerals during Laterization?

This research was financially supported by FEDER Funds and the following Spanish Projects: PID2019-105625RB-C21 and RTI2018099157AI00 granted by the Ministerio de Ciencia, Innovacion y Universidades to JAP and JMGJ, respectively. Additional funding was provided by the Ramon y Cajal Fellowship RYC-2015-17596 to JMGJ. This is also a contribution from the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (www.gemoc.mq.edu.au) and the ARC Centre of Excellence for Core to Crust Fluid Systems (www.ccfs.mq.edu.au). TA was supported by the Centre of Advanced Mining and Metallurgy (CAMM; www.ltu.se/centres/o/camm).In this short communication, we present preliminary data on the Re-Os isotopic systematics of platinum-group minerals (PGM) recovered from different horizons in the Falcondo Ni-laterite in the Dominican Republic. The results show differences in the Os-isotope composition in different populations of PGM: (i) pre-lateritic PGM yield Os-187/Os-188 varying from 0.11973 & PLUSMN; 0.00134 to 0.12215 & PLUSMN; 0.00005 (2 sigma uncertainty) whereas (ii) lateritic PGM are more radiogenic in terms of Os-187/Os-188 (from 0.12390 & PLUSMN; 0.00001 to 0.12645 & PLUSMN; 0.00005; 2 sigma uncertainty). We suggest that these differences reflect the opening of the Re-Os system in individual grains of PGM during lateritic weathering. The implications of these results are twofold as they will help to (1) elucidate the small-scale mobility of noble metals in the supergene setting and therefore the possible formation of PGM at these very low temperatures, (2) better refine the Os-isotopic datasets of PGM that are currently being used for defining dynamic models of core-mantle separation, crustal generation, and fundamental plate-tectonic processes such as the opening of oceans.FEDER by the "Ministerio de Ciencia, Innovacion y Universidades" PID2019-105625RB-C21 RTI2018099157AI00Spanish Government RYC-2015-17596Centre of Advanced Mining and Metallurgy (CAMM