内蒙古八大关矿区印支期岩浆活动及其找矿意义  

Indo-Chinese magmatic activity in the Badaguan ore district of Inner Mongolia and its metallogenic implications

作　　者：康永建[1] 佘宏全[1] 向安平[1] 田京[1,2] 李进文[1] 杨郧城[1] 郭志军[1] 董旭舟[2] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质大学地球科学与资源学院,北京100083

出　　处：《中国地质》2014年第4期1215-1225,共11页Geology in China

基　　金：国家基础科研项目(2013CB429803);中国地质调查局地质调查项目(1212011120992;1212011309011)联合资助

摘　　要：通过对八大关矿区主要花岗岩体进行了系统采样，其镜下鉴定结果显示该区侵入岩主要为花岗岩、黑云母花岗岩、花岗斑岩、钾长花岗岩、花岗闪长斑岩；6件样品的LA-MC-ICP-MS锆石U-Pb年龄主要在243.87~231.63 Ma。结合成矿斑岩的形成时代，矿区主要侵入岩均形成于印支期，并不存在海西期或燕山期侵入岩体。根据岩体年龄的分布情况，将矿区印支期岩浆活动划分为243.87~237.11 Ma和231.63~229.00 Ma 2个阶段，早阶段岩浆活动主要形成矿体围岩；而铜钼矿化主要与晚阶段岩浆活动有关。此外，整个鄂霍次克造山带两侧的印支期岩浆活动也具有两阶段的特点，且与鄂霍次克洋的俯冲密切相关，考虑到两侧已查明的印支期超大型-大型斑岩型矿床，认为八大关矿区外围及额尔古纳地区存在寻找印支早期斑岩矿床的可能性。Systematical sampling of major granite rocks in the Badaguan ore district was conducted in this paper. Microscopic identification results reveal that the primary rocks include granite, biotite granite, granitic porphyry, moyite, and granodiorite porphyry, whereas LA-MC-ICP-MS zircon U-Pb ages of the six samples vary in the range of 243.87-231.63 Ma. Combined with emplacement ages of the metallogenic porphyry, it is inferred that all intrusive rocks were developed in the Indo-Chinese period, without existence of Hercynian or Yanshanian intrusions. According to the distribution of the ages, Indosinian magmatic activities were mainly concentrated in 243.87-237.11 Ma and 231.63-229.00 Ma, and surrounding rocks formed at the early stage of magmatic activity. Copper and molybdenum mineralization principally occurred at the late stage of magmatic activity. In addition, Indo-Chinese magmation on both sides of Okhotsk orogenic belt also have the similar two-stage characteristics, which was closely related to subduction of the Okhotsk Ocean. Based on summarizing the situation on both sides of the identified porphyry deposit, the authors consider that there exists possibility in the search for porphyry deposits of the early Indosinian period in the periphery of the Badaguan ore district or/and Ergun area.

关 键 词：LA-MS—ICP—MS锆石U—Pb 岩浆活动 印支期 八大关 

分 类 号：P588.11[天文地球—岩石学] P612[天文地球—地质学]