Abstract

Five post-Palaeozoic metallogenic environments are recognized in Pakistan and adjoining regions: 1. Mississippi Valley-type fluorite, barite and barite-galena deposits generated in Jurassic limestones on the northern miogeoclinal margin of the Indian Shield, perhaps during incipient rifting heralding India's separation from Gondwanaland; 2. chromite deposits in serpentinized dunite, manganese-oxide deposits in layer-1 sediments and a cupriferous massive sulphide occurrence in layer-2 basalts generated within an ophiolite complex at a Tethyan oceanic spreading centre; 3. porphyry copper–molybdenum, manto-type copper, Kuroko-type massive sulphide, vein copper, contact–metasomatic copper and iron, and volcanogenic iron deposits generated in Cretaceous-Cenozoic times by intrusive and extrusive calc-alkaline magmatism along the southern edge of the Iran-Afghanistan microcontinental plate during northward subduction; 4. stibnite occurrences emplaced in the intracontinental Chaman transform fault system during post-early Miocene times; and 5. sandstone-type uranium deposits in Siwalik molasse-type sediments shed during post-early Miocene uplift of the Himalaya. Juxtaposition of the miogeoclinal, ophiolitic and Cretaceous calc-alkaline metallogenic provinces resulted from suturing of the Indian plate with the southeastern margin of the Iran-Afghanistan microcontinent, representing final closure of eastern Tethys. Subsequent renewed northward motion of the Indian plate, causing crustal shortening and uplift along its northern edge, produced the transform-fault and molasse-basin provinces and, along the Makran segment of the plate boundary unaffected by continental collision, the post-early Miocene calc-alkaline province.

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