OCCURRENCES OF SOLID INCLUSIONS OF SILICATE AND BASE METAL SULFIDE MINERALS IN CHROMITITE OF KHANOZAI OPHIOLITE, PAKISTAN: EVIDENCE FROM MELT EVALUATIONS

Abstract

Chromitite bodies occur in the wide mantle portion of Khanozai ophiolite. This peridotite is largely composed of harzburgite, dunite and minor lherzolite. Chromitite occurs in Khanozai ophiolite mainly in massive, disseminated, banded and nodular forms. The Khanozai chromitites contains a variety of silicate and BMS mineral inclusions. They include anhydrous silicates like olivine, clinopyroxene, hydrous silicate inclusions of amphibole, and BMS mineral inclusions such as millerite, chalcopyrite, stibnite, and occasional pyrite and linnaeite. The silicate mineral inclusions occur as monomineralic as well as polymineralic phases. The shapes of these inclusions tend to follow the growth plane of host chromite. Textures and forms of these inclusions reveal that some inclusions were trapped during magmatic stage, whereas many inclusions were trapped during recrystallization of chromite. BMS inclusions are millerite, chalcopyrite, and stibnite. They occur isolated inclusions and at some places associated with silicate mineral inclusions. It is suggested that these BMS inclusions were generated due to the separation of sulfide-bearing liquid from silicate magma.