Petrology and Mineralization Potential of the Chilas, Jijal,and Related Segements of the Basal Ultramafic-Mafic CumulateComplex, Kohistan Accreted Island Arc Terrane

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The Kohistan exotic terrane of N. Pakistan was accreted to Asia in the Mid-Cretaceous and turned "edge-up" to expose in plan view an essentially complete vertical section through the crust and upper mantle of an intra-oceanic island arc complex. Beneath the volcanic and calc-alkaline batholith sequence is an immense lower crustal mafic-ultramafic-layered cumulate complex that provides a record of the differentiation processes by which "primary" basaltics melts from the mantle evolved in the lower crust to yield the high-alumina basalts and basaltic andesites that dominate the eruptive sequence. The plutonic layered cumulates provide important evidence regarding the petrogenesis of the calc-alkaline magma series that is quite unlike evidence deduced from the study of phenocryst assemblages in lavas. The cumulate complex is one of the world's largest exposures of layered mafic- ultramafic rocks and is potentially a major storehouse of mineral wealth. By means of integrated field studies and whole-rock and mineral geochemical studies in a series of traverses across the cumulate series, this cooperative study involving geoscientists from Azad Jammu and Kashmir University and Purdue University is expected to clarify important petrogenetic questions and to screen the cumulate sequence for stratigraphic intervals most promising as hosts to platinum, nickel, copper, chromium, and vanadium ore deposits, employing innovative ore-petrogenetic concepts and lithogeochemical exploration techniques.