Mesozoic granitic magmatism and gold-molybdenum polymetallic mineraliza-tion in Aohan area,Inner Mongolia
The Aohan area in Inner Mongolia is located in the transition zone between the North China Craton and the Xing'an-Mongolia Orogenic Belt,serving as an important gold-molybdenum polymetallic mineralization concen-tration area on the northern margin of the North China Craton,with fruitful prospecting outcomes in recent years.Based on the systematic analysis of the geological and geochemical characteristics of the Zhuanshanzi and Jin-changgouliang large gold deposits,the Baituyingzi large tungsten-molybdenum polymetallic deposit,as well as the newly discovered Bajia large lead-sliver-zinc deposit and the Tengkeli molybdenum deposit,this research dis-cusses the genesis of the deposits and the regional tectono-magmatic evolution,proposing the metallogenic poten-tial and direction for gold-molybdenum polymetallic mineral exploration in the area. The findings indicate that the gold-molybdenum polymetallic mineralization in the Aohan area is closely related to the Indosinian and Yan-shanian granitic magmatism,with mineralization mainly occurring during the Triassic and the Late Jurassic-Early Cretaceous periods. The Indosinian and Yanshanian fertilized intrusions generally belong to the peraluminous to weakly peraluminous high-K calc-alkaline series of granites,exhibiting right-leaning distribution characteristics enriched in light rare earth elements,enrichment of large ion lithophile elements,and depletion of high fiield strength elements,formed under an extensional setting influenced by the Paleo-Asian and Pacific tectonic do-mains,respectively. The genetic type of gold deposit is mainly magmatic-hydrothermal vein type,and the genetic type of molybdenum deposit is mainly porphyry-type,controlled by tectono-magmatic activities,with the Indosin-ian and Yanshanian felsic magmatic rocks and NW-to nearly NS-trending faults serving as important prospecting indicators. The Zhuanshanzi gold deposit has a prospecting potential for porphyry-and skarn-type gold-copper deposits,while the Jinchanggouliang and Zhuanshanzi gold mining areas and their peripheries have potential for epithermal gold polymetallic deposits. Drawing on the prospecting experience from the Baituyingzi tungsten-mo-lybdenum polymetallic deposit and the Bajia lead-sliver-zinc deposit,it is suggested to focus on the comprehen-sive use of geological,geochemical,and geophysical methods to search for tungsten,molybdenum,lead,zinc,and silver polymetallic deposits in covered areas.
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