粤东铁坑坳铁锡多金属矿床锆石及锡石U-Pb年代学、Nd-Hf同位素特征及其意义  

Zircon and cassiterite U-Pb geochronology and Nd-Hf isotope geochemistry of Tiekeng’ao Fe-Sn polymetallic deposit in eastern Guangdong and its geological significance

作　　者：张志涛 柯昌辉[1] 徐林刚[2] 马收先[1] 陈懋弘[1] 叶会寿[1] 潘玉峰 ZHANG ZhiTao;KE ChangHui;XU LinGang;MA ShouXian;CHEN MaoHong;YE HuiShou;PAN YuFeng(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;No.273 Geological Team of Guangxi Zhuang Autonomous Region,Guigang 537100,Guangxi,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资源评价重点实验室,北京100037 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]广西壮族自治区二七三地质队,广西贵港537100

出　　处：《矿床地质》2022年第3期543-566,共24页Mineral Deposits

基　　金：国家重点研发计划项目(编号:2017YFC0601403);中国地质调查局项目(编号:DD20201173、DD20221684)联合资助。

摘　　要：铁坑坳铁锡多金属矿床位于粤东莲花山断裂带西部,矿区出露的花岗岩类主要有粗粒二长花岗岩和花岗闪长斑岩,花岗质岩石与碳酸盐岩的接触带中发育铁锡多金属矿化。该矿区的成岩成矿时代尚不明确,成矿与哪一种岩体具有成因上的联系也不清楚。文章选择与铁锡多金属矿体相关的花岗岩类的锆石和块状矿石中的锡石,首次开展LA-ICP-MSU-Pb定年和Nd-Hf同位素研究。结果表明:粗粒二长花岗岩和花岗闪长斑岩的锆石U-Pb年龄分别为(132±1)Ma(n=24,MSWD=0.78)和(94±1)Ma(n=25,MSWD=1.80);块状矿石中锡石U-Pb年龄为(130±3)Ma(n=36,MSWD=0.62),成矿时代与粗粒二长花岗岩形成时代基本一致,均形成于早白垩世;粗粒二长花岗岩的锆石ε_(Hf)(t)变化于-4.9~-0.1,平均值为-2.8,地壳Hf模式年龄T_(DMC)=1192~1497 Ma,平均值为1366 Ma,全岩ε_(Nd)(t)值介于-8.8~-8.7,Nd同位素二阶段模式年龄T_(DM2)变化于1630~1642 Ma;花岗闪长斑岩的锆石ε_(Hf)(t)变化于-5.7~-2.9,平均值为-4.4,地壳Hf模式年龄T_(DMC)=1342~1523 Ma,平均值为1440 Ma,全岩ε_(Nd)(t)值介于-5.4~-4.9,Nd同位素二阶段模式年龄T_(DM2)变化于1291~1332 Ma。Nd-Hf同位素综合研究表明,粗粒二长花岗岩的源区物质主要来自于中元古代地壳,有少量幔源组分或新生地壳的加入,花岗闪长斑岩的源区物质中幔源组分或新生地壳的混入比例高于粗粒二长花岗岩。The Tiekeng'ao Fe-Sn polymetallic deposit is located in the west of the Lianhuashan fault zone in eastern Guangdong Province.Granites exposed at the deposit include coarse-grained monzonitic granite and granodioritic porphyry.The massive Fe-Sn polymetallic ore bodies occur within the contact zone between granite and carbon‐ates.The ages of mineralization and magmatic intrusions at the Tiekeng'ao deposit are unclear,hindering a better understanding of the magmatic processes and their relations with metallogenesis.Here,we carried out LA-ICP MS U-Pb dating and Nd-Hf isotope studies of zircons and cassiterites extracted from granitoids and massive ores,respectively.Zircon LA-ICP-MS U-Pb dating of the coarse-grained monzonitic granites and granodioritic porphy‐ry yielded concordant ages of(132±1)Ma(n=24,MSWD=0.78)and(94±1)Ma(n=25,MSWD=1.80),respective‐ly.The U-Pb dating of the cassiterites from the massive ore is(130±3)Ma(n=36,MSWD=0.62),overlapping with the coarse-grained monzonitic granite within analytical error.Zirconε_(Hf)(t)values of coarse-grained monzonitic granites vary from-4.9 to-0.1 with an average value of-2.8.The crustal Hf model age(T_(DMC))is between 1192 Ma and 1497 Ma with an average age of 1366 Ma,and the whole rockε_(Nd)(t)values vary from-8.8 to-8.7.Neodymium isotope two-stage model age T_(DM2)varies between 1630 Ma and 1642 Ma.Zirconε_(Hf)(t)values of granodioritic porphyry range from-5.7 to-2.9,with an average of-4.4.The crustal Hf model age is between 1342 Ma and 1523 Ma,with an average of 1440 Ma.Theε_(Nd)(t)of the whole rock ranges between-5.4 and-4.9,with the Nd isotope two-stage model age T_(DM2)varies between 1291 Ma and 1332 Ma.The Nd-Hf isotopic compo‐sition indicates that the coarse-grained monzonitic granite is initially derived from the Mesoproterozoic crust,with a small proportion of mantle and juvenile crust components contamination.In contrast,the granodioritic por‐phyry is mainly derived from the partial melting of the Mesoproterozoic crust with a more significant

关 键 词：地球化学 锡石U-Pb定年 LA-ICP-MS锆石U-PB定年 Nd-Hf同位素 花岗岩类成因 铁坑坳铁锡多金属矿床 粤东 

分 类 号：P618.31[天文地球—矿床学] P618.44[天文地球—地质学]