Solid inclusions in the chromitites of Geofizicheskoe-VII deposit (Kempirsay massif, Kazakhstan)

Abstract

Solid inclusions in chromite grains of Geofizicheskoe VII deposit located in Dzharlybutak area hosting the largest ophiolitic chromitite resources in the world are described. We show that mineralogical composition of inclusions (olivine, serpentine, chlorite, pargasite, PGM, base metal sulfides) is more various in comparison to that of host ultramafic rocks (olivine, enstatite, serpentine). PGM are predominantly disulfides of refractory PGE, rarely – native Ru-Os-Ir solid solutions. PGM inclusions always locate in chromite grains and they often form intergrowth with chlorite. We infer that the inclusions in chromite grains would been formed by solid state processes (deformation-induced breakdown of pyroxenes, impurity segregation in spinel, etc.) during high-T plastic flow and recrystallization at upper mantle conditions.