PETROLOGY AND GEOCHEMISTRY OF CHROMITITE AND PERIDOTITE FROM KHANOZAI OPHIOLITE, NORTHERN BALOCHISTAN, PAKISTAN

The Khanozai Ophiolite is an important fragment of Zhob valley ophiolite belt. This contains thick serpentinized mantle peridotite which consists of ultramafic tectonite and transition zone. Ultramafic tectonite comprises of largely harzburgite with subordinate dunite and lherzolite whereas transition zone is dominantly made up of dunite with subordinate harzburgite. Peridotite contains thick chromitite bodies. The chromitite of Khanozai Ophiolite is found as pods, lenses and layered shapes. These chromitites bodies occur in massive, disseminated and nodular forms. The chromitite for Khanozai Ophiolite is classified as high-Cr chromitite based on Cr# (aver. 0.72). Chromite grains in chromitite are largely uniform in composition but few grains show ferrit-chromite alteration along veins and grain margins.  High Cr#, low TiO2 and chromite composition of high-Cr indicated that high-Cr chromite ore deposits in the mantle portion have been crystallized from parental melt of boninitic composition. Geochemical composition of chromite spinels in chromitites and peridotite suggests that the chromitite and peridotite of Khanozai Ophiolite was formed in suprasubduction zone environment.   Download Full Paper