滇西北衙金多金属矿床锆石U-Pb和辉钼矿Re-Os年龄及其地质意义  

Zircon U-Pb and molybdenite Re-Os dating for the Beiya gold-polymetallic deposit in the western Yunnan Province and its geological significance

作　　者：和文言[1] 莫宣学[1] 喻学惠[1] 和中华[2] 董国臣[1] 刘晓波[1] 苏纲生[2] 黄雄飞[1] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,地球科学与资源学院,北京100083 [2]云南黄金矿业集团股份有限公司,昆明650224

出　　处：《岩石学报》2013年第4期1301-1310,共10页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划项目(2009CB421002);国土资源部公益性行业科研专项(200911007-3);地质过程与矿产资源国家重点实验室开放基金(GPMR2011)联合资助

摘　　要：北衙金多金属矿床位于金沙江-哀牢山富碱斑岩带中段,近年来在矿产勘查中取得重大突破,金储量已达超大型矿床规模,并伴生铁、铜、银、铅、锌等金属矿种。本文通过对矿区内石英正长斑岩进行锆石LA-ICP-MSU-Pb定年,确定其成岩年龄为36.48±0.26Ma;并对矽卡岩型矿体中的辉钼矿样品进行Re-Os同位素定年,首次获得北衙金多金属矿床高精度的成矿年龄为36.87±0.76Ma,测试结果显示成岩与成矿年龄基本一致。辉钼矿中Re含量指示成矿作用与岩浆壳幔混合作用有关。北衙金多金属矿床成岩和成矿年龄与哀牢山-金沙江富碱斑岩成矿带的成岩与成矿作用年龄相一致(40～35Ma),表明其形成受控于相同的地球动力学背景,是在印度与欧亚大陆碰撞背景下,构造体制发生转变,导致加厚下地壳或上地幔的部分熔融而引起的岩浆-热液-成矿事件。The Beiya gold-polymetallic deposit lies in the middle of the Cenozoic Jinshajiang-Ailaoshan alkali-rich intrusion belt in the western Yunnan Province. It is a representative ore deposit in studying Himalaya epoch mineralization and shows bright future for further prospecting. The first highly precise dating of the rock-forming and mineralization in Beiya gold-polymetallic deposit is provided in this paper. The U-Pb LA-ICP-MS dating of the zircon from Hongnitang quartz syenite porphyry yields an age of 36.48±0.26Ma. Re-Os dating of molybdenite separated from the skarn ore bodies gives a model age of 36.87±0.76Ma. These ages suggest that the mineralization in the Beiya gold-polymetallic deposit is genetically associated to the quartz syenite porphyry. The Re contents of molybdenite indicate that the ore-forming materials are derived from mantle and crust. Based on the same ages of the rock-forming and mineralization in Beiya gold-polymetallic deposit and other deposits in jingshajiang-Ailaoshan metallogenic belt, it is proposed that these deposits all occurred under the background of India-Eurasia collision when the tectonic regime changing make the thickened lower crust and upper mantle melt partially.

关 键 词：成矿背景 锆石U-Pb年龄 RE-OS同位素年龄 北衙金多金属矿床 滇西 

分 类 号：P597.3[天文地球—地球化学] P618.51[天文地球—地质学]