内蒙古敖汉地区中生代花岗质岩浆活动与金钼多金属成矿作用

内蒙古敖汉地区处于华北克拉通与兴蒙造山带的过渡区,是华北地台北缘一个重要的金钼多金属矿化集中区,近年来找矿成果丰硕。在对撰山子和金厂沟梁大型金矿、白土营子大型钨钼多金属矿以及近年新发现的八家大型锌银铅矿和腾克力钼矿的地质地球化学特征系统分析的基础上,文章探讨了矿床成因与区域构造岩浆演化,提出了本区金钼多金属成矿潜力与找矿方向。结果显示,敖汉地区金钼多金属成矿与印支期、燕山期花岗质岩浆侵位密切相关,成矿主要发生于三叠纪和晚侏罗世—早白垩世,具有多期多阶段性特征。印支期和燕山期成矿岩体总体均属于准铝质-弱过铝质高钾钙碱性系列花岗岩,表现为轻稀土富集的右倾配分特征,大离子亲石元素富集,高场强元素亏损,分别形成于古亚洲洋和古太平洋构造域影响下的伸展背景。金矿床成因类型主要为岩浆热液脉型,钼矿床成因类型主要为斑岩型,受构造-岩浆岩联合控制,印支期和燕山期中酸性岩浆岩及北西向-近南北向断裂是重要的找矿标志。撰山子金矿具有良好的斑岩-矽卡岩型金铜矿床找矿前景,金厂沟梁和撰山子金矿区及外围具有寻找浅成低温热液型金多金属矿床的潜力。借鉴白土营子钨钼多金属矿田和八家锌银铅矿床的找矿经验,应注重综合利用地质、地化、物探等手段在覆盖区寻找钨铅锌银多金属矿床。

Mesozoic granitic magmatism and gold-molybdenum polymetallic mineralization 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 concentration 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 Jinchanggouliang 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 discusses the genesis of the deposits and the regional tectono-magmatic evolution, proposing the metallogenic potential 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 Yanshanian 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 field strength elements, formed under an extensional setting influenced by the Paleo-Asian and Pacific tectonic domains, 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 Indosinian 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-molybdenum polymetallic deposit and the Bajia lead-sliver-zinc deposit, it is suggested to focus on the comprehensive use of geological, geochemical, and geophysical methods to search for tungsten, molybdenum, lead, zinc, and silver polymetallic deposits in covered areas.