Metallogenesis And Mineral Resources Assessment In Eastern Kunlun Orogenic Belt

Abstract: Eastern Kunlun orogenic belt is located in the south of Caidam continentalblock. Its regional geologic settings are very complicated including diverse regionalstrata, magmatic rocks and structures. Three regional faults strike nearly EW; they arefaults of North of Eastern Kunlun, Middle of Eastern Kunlun and South of EasternKunlun. Predecessors divided East Kunlun orogenic belt into three tectonic belts by theabove three regional faults. Regional Strata characterized as follows in each tectonic belt.At first, basements are different from south to north. Paleoproterozoic Jinshuikou Groupformed crystallized basement in North belt and Middle belt of Eastern Kunlun, andWanbaogou Group just formed fold basement. The second, activities are different fromsouth to north. Binggou Group was a stable cover strata laying on Jinshuikou Group, andNachitai Group stood for marine active environment laying on Wanbaogou Group. At last,Carboniferous and Permian were stable strata in North belt and Middle belt of EasternKunlun, and were active strata in South belt of Eastern Kunlun. Regional magmatism wasstrong also, and every epoch or type of magmatic rocks occurred in whole EasternKunlun Mountain. There are many neutral-acid magmatic rocks assemblages related withsubduction -collision of plates and some bimodal magmatic rocks assemblages formed onthe stage of continental extension in post-orogenic epoch. And there existed still a little ofmafic-ultramafic rocks assemblages consisted of ophiolites or basic-ultrabasic rocks. On the basis of regional geologic settings, it was thought that geologic meanings ofthe above three tectonic belts were Caledonian back-arc rift belt of North of EasternKunlun, basement uplifting and granite belt of Middle of Eastern Kunlun and compositecollage belt of South of Eastern Kunlun. The Eastern Kunlun orogenic belt went throughcomplicated geodynamic evolution. On Meso-Neoproterozoic, Caidam crustal block hadformed, and Kuhai ancient land dispersed and then converged. At the same time,Wanbaogou Group in south of the fault of Middle of Eastern Kunlun were oceanic basaltplateau formed by mantle plume in Pre-Proto Tethys Ocean. On Caledonian, a trench-arcsystem was formed in the north of Wanbaogou basalt plateau because of southwardsubduction of proto Tethys Ocean. To the north of it, the southern margin of Caidamblock was transferred from passive continental margin into active one, and a back-arc riftbelt was formed in the fault of North of Eastern Kunlun, during southward subduction of4oceanic plate. A whole trench-arc-basin system was formed. On late Caledonian,Wanbaogou basalt plateau and Kuhai ancient land had converged with southern margin ofCaidam block, and back-arc rift belt of North of Eastern Kunlun had also closed. Thenthe subduction zone moved to the fault of South of Eastern Kunlun. On early Indosinian,the Tethys Ocean on the south of the subduction zone of South of Eastern Kunlun closed,and Bayan Har fold belt converged with southern margin of Eastern Kunlun. It meantEastern Kunlun marginal orogenesis had ended, and whole Eastern Kunlun orogenic beltcame into a stage of intracontinental evolution. On late of Indosinian, strong interactionof crust-mantle occurred, and lithosphere detachment caused mantle magma diapirism.Tectonic system of Eastern Kunlun transferred from a compressive system to a stretchingone, and a lot of mantle substance and energy took part in tectonism, magmatism andmetallogenesis. Based on the above research, we analyzed regional metallogenic conditions fromgeology, geophysics and geochemistry. Considering regional strata, some source bedswith ore-bearing strata controlled apparently metallogenesis. The strata containedhydrothermal siliceous rock or siliceous albitite ether formed some favorable source bedsand established substantial foundation for later diplogenetic metallogenesis (e.g.Kendekeke ore field) or formed directly industrial ore deposit (e.g.