Platinum group element (PGE) potentials of the South-Western Anatolian chromite deposits

In this study, thirteen chromite deposits (chromitites) in South-western Anatolia are investigated for their platinum-group element (PGE) potentials. Micro-textures, chromian-spinel and silicate chemistries of the sampled deposits suggest that these chromitites are formed via melt/rock interaction in a supra-subduction zone environment.In general, whole-rock PGE abundances of the chromitites are low and currently non-economic for PGE mining operations. High PGE and base-metal (BM) content is observed in only one sample made of three different lithologies (massive chromitite, disseminated chromitite and dunite) in Elmaslar Chromite Deposit (ECD). Ir-group (IPGE) and Pd-group (PPGE) element fractionation in the investigated deposits are generally in favor of IPGE phases which are crystallized in chromian-spinel. The ECD samples investigated in detail present variation in normalized PPGE and IPGE ratio versus their constant total PGE values. This situation suggests local fractionation of the PPGE and IPGE along the deposit during the formation of the chromitite pod.The PGE and BM phases observed in the deposits are in two generations. Primary phases are generally observed in chromian-spinel, whereas the secondary phases are generally related to silicates. It is interpreted that the primary phases are magmatic and the secondary phases are hydrothermal in origin. Certain minor elemental variations in certain minerals facilitated making an approach on the sulfur fugacity, temperature and cooling rate during the crystallization of chromitites. High primary BM sulfide enrichment in the exceptionally anomalous sample in ECD suggests that sulfur fugacity is partially stabilized and sulfur saturation is reached in only certain parts of the pod.