The emerald-hosting magnesite-rich rocks from Swat, NW Pakistan
Abstract
The Main Mantle Thrust melange zone in Swat contains carbonate-rich rocks (magnesite ± talc ± quartz ± chrome spinel/ Cr-magnetite/ ferritchromite ± fuchsite ± tourmaline ± chlorite) which locally host emerald mineralization. Detailed field and mineralogical studies suggest that these rocks were probably formed by talc-carbonate alteration of the spatially associated, previously serpentinized ultramafic rocks in the area. This transformation may have taken place at 250-550oC and was probably caused by CO2-bearing fluid released by the metamorphism of the underthrusted sedimentary rocks of the Indian plate.
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