广东鹦鹉岭钨多金属矿床中黑云母花岗岩LA-ICP-MS锆石U-Pb定年和Hf同位素特征及其地质意义  

Zircon U-Pb geochronological and Hf isotopic constraints on petrogenesis of Yingwuling tungsten polymetallic deposit in Guangdong Province and its geological significance

作　　者：郑伟[1] 陈懋弘[2] 赵海杰[2] 赵财胜[3] 侯可军[2] 刘建新 李学孟 常利忠[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点开放实验室,北京100037 [3]国土资源部科技与国际合作司,北京100812 [4]广东省地质建设工程集团公司,广州510080

出　　处：《岩石学报》2013年第12期4121-4135,共15页Acta Petrologica Sinica

基　　金：国家重点基础研究973项目(2012CB416704);国家自然科学基金项目(40930419);中国地质调查局地质调查工作项目(1212011120831)联合资助

摘　　要：钦杭成矿带不仅是扬子与华夏陆块的碰撞拼接带，而且也是华南地区独具特色的铜金和钨锡多金属成矿带。本文以鹦鹉岭钨钼多金属矿床含矿岩体-黑云母花岗岩为研究对象，首次开展了锆石 LA-ICP-MS U-Pb 同位素定年和Hf同位素特征研究。获得其锆石206Pb/238U同位素加权平均年龄为81.30.6Ma，其与已获得的辉钼矿Re-Os等时线年龄83.01.7Ma在误差范围内基本一致，表明鹦鹉岭多金属矿床成岩成矿作用同时发生于晚白垩世，即中生代燕山晚期。该岩体的锆石εHf（t）值大多数为负值，少部分大于0，变化于-5.72~1.40，平均值为-2.09，表明其主要成岩物质来自于壳源。εHf（t）-t图解上，εHf（t）均落在球粒陨石演化线之下，呈弱亏损的特征，指示地壳部分熔融的岩浆可能有少量地幔物质的加入。两阶段模式年龄tDM2=1.06~1.51Ga，指示成岩物质主要来源于中元古代古老地壳岩石的部分熔融。结合已有的地球化学、岩石学和区内高精度成岩成矿年龄资料，表明鹦鹉岭钨多金属矿床形成于华南岩石圈伸展-减薄的环境下。Qin-Hang metallogenic belt is not only a collision of Yangtze Craton and Cathaysian Block, but also a unique copper-gold and tungsten-tin polymetallic metallogenic belt in South China. As the study examples of ore-bearing biotite granite in the Yingwuling tungsten polymetallic deposit, we performed in situ zircon U-Pb dating and Hf isotopic analyses for the first time. Twenty-one zircons of ZK2805-Y-1 sample yield excellent concordant results with a weighted mean 206Pb/238U age of 81.30.6Ma （n=22,MSWD=0.85）. So it is consistent with previous molybdenite Re-Os isochron age （83.01.7Ma） within error. It indicates that both the emplacement of the ore-bearing biotite granite and associated tungsten-tin polymetallic mineralization in the Yingwuling mining area occur in the Late Cretaceous. Most εHf（t） values of the Yingwuling biotite granite are minus. εHf（t） values have a range of -5.72~1.40, and the mean is -2.09, which mainfests that they are mainly crustal origin. On the εHf（t） versus age diagram, εHf（t） are below the evolution curve of chondrite and analyzed points show weak-depleted characteristics, indicating that partial-melting crust magma may have a small amount of mantle material to join. The age of stage （tDM2 ） is 1.06~1.51Ga, showing rock-forming materials mainly derived from the ancient Middle Proterozoic crustal partial melting. Based on the data of geochemistry, petrology and precise isotope ages, we can infer that the Yingwuling tungsten polymetallic deposit formed under the environment of lithospheric extension and thinning.

关 键 词：锆石SHRIMP U-Pb定年 Hf同位素 鹦鹉岭钨多金属矿 晚中生代 广东省 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]