Tectonic Evolution And Metallogenic Seires Of Ongniud Banner,in The Central-South Part Of The Great Xinean Range

On the basis of field geological work, the author studied comprehensively intrusive rocks,volcanic rocks, metamorphic rocks of Ongniud Banner in Inner Mongolia with theoreticalknowledge such as isotopic geochronology, rock geochemistry, petrology, mineralogy and modernstratigraphy. The U-Pb age of single-grain zircon from mylonite schist in Seertengshan Group is2645±86Ma. It reflects the greenstone belt tectonic attribute of continental nucleus, rather than theCaledonian fold belt. The U-Pb age of single-grain zircon from plagioclase amphibolite inWinduermiao Group is1620±160Ma, and it is preliminary considered the time of ophioliteformation. In this geological period, Sino-Korean plate has been cracking, and Palaeo-Asian Oceanpreliminary shaping. Late Paleozoic granites are of the features from volcanic arc granites. TheU-Pb age of single-grain zircon from granites is265.2±2.8Ma,265.4±6.6Ma,265.4±5.5Ma. Itshows that the North China plate and Siberia plate collision is the peak period in late Permian,eventually Siberian plate and North China plates cohering in Xilamulun river area. The earlyPermian volcano-sedimentary sequence and geochemical characteristics suggest the region locatedstill in the Palaeo-Asian Ocean, rather than the intracontinental taphrogenic trough in EarlyPermian. Mesozoic volcanic rocks do not have the feature of the bimodal volcanic rock,K60=2.696%, to estimate the crustal thickness of the Greater HingganMountains region is about49.51km. Puts forward the main three metallogenic type, the corresponding different tectonicposition and geological unit.