Microprobe analytical Data on Chromitites from the Muslimbagh Ophiolite, Baluchistan, Pakistan
Abstract
Thirteen chromitites associated with ultramafic rocks of Muslimbagh consist of high chromium Al-chromite + serpentine +-chlorite+- magnetite +-Mg-Fe carbonate+- olivine. Ultramafic tectonites cannot be distinguished from ultramafic cumulates on the basis of chromite composition in the chromitites. However, chromitites associated with the tectonites tend to have zoned and those in the cumulates unzoned chromite. The outer zones have developed during the alteration (principally chloritization) of the rock and are enriched in Fe" /(Fe" + Mg) and, in some cases, Cr/(Cr+Al). One analyzed olivine is highly magnesian (Fom) due possibly to m exchange of Fe=Mg with the associated chromite at 700-800 oC.
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