Evaluating the abundance and variations of platinum and palladium elements in pyroxene and chromite minerals of pyroxenites from Neyriz area
Subject Areas :
1 - Tehran University
2 -
Keywords: Ophiolite Pyroxenit Platinum group element Neyriz. ,
Abstract :
Neyriz ophiolite in Fars Province which formed as the result of the closure of Neo-Tethys ocean and Arabian-Iranian plate collision in Late Cretaceous, has high potential for ore deposits, in particular chromite. Pyroxenite is one of the main constituent units of ophiolites and electron microprobe analysis (EMP) shows that clinopyroxene (diopside), orthopyroxene (enstatite) and olivine (cherysolite) are the most abundant minerals. The abundances of MgO, Fe2O3, Al2O3, Cr2O3 and TiO2 in chromites of Neyriz pyroxenites show affinities with the podiform chromites which formed from magma with bonititic composition with high Cr# (100 Cr/(Cr+Al)) and low content of TiO2. The results of Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) analyses accompanied with the fire assay precon-centration demonstrate that platinum group elements in Neyriz ophiolite are more enriched relative to those of the primitive mantle. In addition, the concentrations of Pt and Pd in chromites within pyroxenites are higher than those of the pyroxene phases. In general, the amounts of these elements in Neyriz pyroxenites are much less than of economic threshold (5 ppm).