冈底斯南缘努日Cu-W-Mo多金属矿床黑云母Ar-Ar定年及其地质意义  

Ar-Ar Age of Biotite from the Nuri Cu-W-Mo Deposit in Tibet,and Its Geodynamic Significance

作　　者：吴昌炟 郑远川[1] 张松[1] 付强[2,3] 徐培言 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院地质研究所,北京100037 [3]北京大学地球与空间科学学院,北京100871

出　　处：《地质学报》2015年第9期1673-1682,共10页Acta Geologica Sinica

基　　金：国家重点基础研究发展计划"973"项目(编号2011CB403100);国家自然科学基金项目(编号41102033;41472076);中国地质调查局地质调查项目(编号1212011121253;12120113037900);基本科研业务费专项项目(编号53200959586)联合资助的成果

摘　　要：努日矽卡岩型Cu-W-Mo多金属矿床位于青藏高原冈底斯南部的克鲁-努日-冲木达斑岩-矽卡岩型铜多金属成矿亚带,具有较大的成矿规模以及独特的矿化组合,并可分为北部Cu-Fe矿段和南部Cu-W-Mo矿段。新近的研究显示努日矿区南北矿段具有不同的成矿时代,表明至少存在着两期Cu矿化事件。本文采集了Cu-WMo矿段内仅发育Cu矿化的石英脉样品,并对与黄铜矿共生的黑云母进行了Ar-Ar同位素定年工作。实验结果显示,黑云母40 Ar/39 Ar坪年龄为23.75±0.18Ma,相应的等时线年龄为23.72±0.28Ma(MSWD=1.5),与前人测得南矿段内和辉钼矿共生的黄铜矿的形成时代基本一致。不同产状Cu矿化具有相同的成矿时代,表明Cu-WMo矿段未发生两期成矿作用的叠加。矿化石英脉显示出张性环境的特征,可能代表了成矿物质由深部隐伏斑岩体向上运移的通道。克鲁-努日-冲木达成矿亚带在晚碰撞阶段发育大规模成矿作用,构成了统一的斑岩-矽卡岩型成矿系统,具有巨大的勘探前景。The Nuri skarn Cu-W-Mo polymetallic deposit is located in the Kelu-Nuri-Chongmuda copper polymetallic belt on the southern margin of the Gangdese metallogenetic belt of the Tibet Plateau, which is characterized by large-scale mineralization and unique assemblages of mineralization. It can be divided into Cu-Fe ore section and Cu-W-Mo ore section. Recent studies show the timing of mineralization between Cu- Fe and Cu-W-Mo ore section is different, which means that there are two stages of mineralization in Nuri at least. In this article, we found an unique type of orebody which only contains chalcopyrite without Mo and W mineralizations. Meanwhile, this type of orebody is characterized by straight quartz vein which contain a large amount of chalcopyrite and biotite. Biotite from the Nuri Cu-W-Mo ore section yielded a well-defined 40Ar/39Ar plateau age of 23.75±0.18 Ma and an isochron age of 23.72±0.28 Ma （ MSWD = 1.5 ）, which represents the formation age of chalcopyrite, and consistent with the formation age of molybdenite intergrowth with chalcopyrite. Based on this, there is only one mineralization event in Cu-W Mo ore section in the Nuri deposit. The mineralized quartz vein shows extentional setting, which may represent migration channel of metallogenic material. Therefore, we suggest that the Kelu-Nuri- Chongmuda metallogenetic belt took place large-scale mineralization in late-collision stage, and formed a uniform porphyry-skarn ore-forming system with great exploration prospect.

关 键 词：Ar-Ar测年 努日矿床 Cu矿化 冈底斯 

分 类 号：P618.2[天文地球—矿床学] P597.3[天文地球—地质学]