Gem Olivine and Calcite Mineralization Precipitated from Subduction-Derived Fluids in the Kohistan Arc-Mantle (Pakistan)
P. Bouilhol et al., The Canadian Mineralogist, Vol. 50, No. 5, 2012, pp. 1291–1304
Geochemical data presented suggests remobilized CO2 and H2O from a subducted island arc helped form the calcite + olivine-bearing veins in Kohistan, Pakistan. The authors provide details on the geologic setting, mineralogy and geochemistry of the vein assemblages, which can yield gem-quality olivine (peridot). The CO2 and H2O from island arc magmas and carbonates mixed with mantle fluids rich in Bo (evidenced by ludwigite-vonsenite needle-like inclusions in olivine) as well as La, Ce, Ta, Cu, and Zn (from trace element analysis). Fluid origin and emplacement are discussed at length with emphasis on macro-geophysical mechanisms within the earth. Gem olivine production data and characterization of the rough was not provided.
Abstracted by Keith A. Mychaluk
