内蒙古那仁乌拉钨多金属矿床成岩成矿年代学研究及其对找矿勘查的指示  

Geochronology of the Narenwula W polymetallic deposit in Inner Mongolia and its implications for ore prospecting

作　　者：王倩[1] 侯可军[1] 张增杰[1] 朱乔乔[1] 王天顺 潘忠飞 唐庆 WANG Qian;HOU KeJun;ZHANG ZengJie;ZHU QiaoQiao;WANG TianShun;PAN ZhongFei;TANG Qing(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Science,Beijing 100037,China;College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China;402 Geological Brigade of Sichuan Bureau of Geology and Mineral Resources,Chengdu 611743,China)

机构地区：[1]中国地质科学院矿产资源研究所,自然资源部成矿作用与矿产资源评价重点实验室,北京100037 [2]贵州大学资源与环境工程学院,贵阳550025 [3]四川省地质矿产勘查开发局四〇二地质队,成都611743

出　　处：《岩石学报》2023年第6期1757-1770,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41603024);国家重点研发计划项目(2021YFC2901900);基本科研业务费(KK2115)联合资助。

摘　　要：内蒙古那仁乌拉石英脉型钨多金属矿床是我国大兴安岭西南段近年来新发现的一个以钨为主,伴生有铋、银、锌、铜的大型矿床。然而,该区经历过多期次复杂的构造-岩浆活动,目前该矿床与区内不同期次岩浆活动的关系还不清楚,这不仅制约了对该矿床成因的认识,也阻碍了该地区钨矿找矿勘查工作的部署。本文选择区内粗粒二长花岗岩中的锆石、独居石以及石英脉型矿体中的黑钨矿、锡石开展精细的原位LA-HR-ICP-MS U-Pb年代学研究,进而构筑精细成岩成矿年代学框架。结果显示,花岗岩的锆石和独居石U-Pb年龄分别为146.2±2.2Ma和144.2±0.8Ma,二者在误差范围内一致,表明含矿花岗岩形成于晚侏罗世;主成矿期石英脉型矿石中的黑钨矿和锡石的U-Pb年龄分别为136.7±1.0Ma和137.8±1.9Ma,二者在误差范围内一致,表明该区钨锡矿化主要发生于早白垩世。由于含矿花岗岩的侵位年龄与成矿年龄之间存在超过10Myr的时差,考虑到同一岩浆-热液演化过程难以长达10Myr,表明含矿花岗岩仅仅为赋矿围岩,而与钨锡矿体无成因上的联系,并暗示区内存在与钨锡成矿有关的早白垩世隐伏的高分异花岗岩小岩体,深部具有钨锡矿找矿潜力。结合区域已有资料,本文提出那仁乌拉钨矿的形成主要受蒙古-鄂霍茨克洋闭合后的伸展过程控制,并可能受到古太平洋俯冲作用远程效应的影响。The Narenwula quartz-vein type tungsten polymetallic deposit,located in the southwestern Great Hinggan Mountains in Inner Mongolia,Northeast China,is a recently discovered large W-Bi-Ag-Zn-Cu deposit.However,the geochronological and genetical relationship between the deposit and the multiple stages of regional tectonic-magmatic events remains unclear,which severely hinders the understanding of the genesis of the deposits and ore deposits exploration in this area.In this paper,LA-HR-ICP-MS U-Pb ages of zircon and monazite in ore-bearing coarse-grained monzogranite as well as wolframite and cassiterite in quartz-vein type ore are studied to constrain the geochronological framework of the granites and the ore.The zircon and monzonite from the monzogranite yielded U-Pb ages of 146.2±2.2Ma and 144.2±0.8Ma,respectively,which are consistent with each other within permitted errors,and thus indicating that the ore-bearing rocks were formed in the Late Jurassic.The wolframite and cassiterite from the quartz-vein type ore yielded U-Pb ages of 136.7±1.0Ma and 137.8±1.9Ma,respectively,indicating that the W-polymetallic deposit were formed in the Early Cretaceous.Since the formation time gap of the granite and the W-polymetallic ore(~10Myr)is larger than the lifetime of a granitic magmas activity,there is no genetic relationship between the monzogranite and W-polymetallic mineralization.These geochronological data indicate that the ore-causative granite should be buried in the deep in the area and there is a high potential for W-polymetallic ore exploration in the deep of the ore district.Combined with the regional metallogenic studies,we propose that the formation of the Narenwula deposit is mainly controlled by the extension process after the closure of the Mongolian-Okhotsk Ocean,and may be superimposed by the remote effect of the subduction of paleo-Pacific plate.

关 键 词：钨多金属矿 黑钨矿U-Pb定年 锡石U-Pb定年 独居石U-Pb定年 锆石U-Pb定年 那仁乌拉 成矿时代 

分 类 号：P618.2[天文地球—矿床学]