Mineralization of the Lianhuashan Sn-polymetallic deposits associated with dynamic metamorphism:Constraints from cassiterite geochemistry and U-Pb geochronology  

作　　者：Jun WANG Liming WANG Shuang YAN Yong MA Diankui XU 

机构地区：[1]CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Geology Bureau for Nonferrous Metal of Guangdong Province,Guangzhou 510080,China [4]Nonferrous Geological Exploration Institute of Guangdong Province,Guangzhou 510080,China [5]Nonferrous Metal Geological Bureau of Guangdong Province 931 Battalion,Shantou 515041,China

出　　处：《Science China Earth Sciences》2023年第7期1664-1677,共14页中国科学（地球科学英文版）

基　　金：supported by the Cooperative Research Fund of the CAS Key Laboratory of Mineralogy and Metallogeny(Grant No.KLMM20200201);the National Natural Science Foundation of China(Grant No.41903016);the President Youth Foundation from Guangzhou Institute of Geochemistry,Chinese Academy of Sciences(Grant No.2019SZJJ-08);the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2019B030302013);the Mineral Geological Survey and Prospecting Prediction in Comprehensive Exploration Area of the China Geological Survey(Grant No.12120114015901)。

摘　　要：The Lianhuashan metallogenic belt in Eastern Guangdong Province(South China)is the most important Sn polymetallic district in the region,hosting many medium-sized deposits such as the Tashan,Xianshuili,and Jiangxikeng.However,the metallogenic mechanism of these deposits remains hotly debated.In this paper,two types of cassiterites(Cst1 and Cst2)have been identified in the Xianshuili and Jiangxikeng Sn deposits,which are hosted in the biotite-mylonite and garnetcordierite-muscovite blastomylonite,respectively.The euhedral Cst1(0.50–1.8 mm)coexists with biotite,feldspar,and quartz.It is platy and zoned with a mosaic structure.The subhedral to anhedral Cst2(0.02–0.35 mm)coexists with metamorphic minerals such as garnet and cordierite,and it is characterized by well-developed porosity and has no zonation.In-situ U-Pb dating of the Cst1 and Cst2 yielded ages of 149.5±1.0 Ma(MSWD=1.6,n=45)and 125.1±2.3 Ma(MSWD=4.5,n=43),respectively.Cst1 is most likely to be related to the intermediate-felsic magmatism that formed Gaojiping Group,whereas Cst2 has relatively high Ta,Nb,Fe,and W contents with obvious rare earth tetragroup effect,and may have formed by the late Early Cretaceous dynamic metamorphism.Results presented here,when combined with regional geology and geochemistry,led us to suggest that the Mesozoic intermediate-felsic volcanic rocks in the LMB are significantly enriched in Sn and F,with high Sn-polymetallic mineralization potential which likely have contributed to the volcanic-related Cst1.In the late Early Cretaceous period,due to the NW-dipping subduction of the paleo-Pacific plate,the intermediate-felsic volcanic rocks underwent dynamic metamorphism that led to Sn mobilization,migration,and precipitation in the regional ductile shear zones,and eventually generating Sn mineralization.We propose that areas beneath Xianshuili and Jiangxikeng have great potential for discovery of new Sn resources.Our findings likely offer practical importance to regional geological ore prospecting.

关 键 词：Lianhuashan metallogenic belt(LMB) Sn-polymetallic deposit CASSITERITE U-Pb geohronology Dynamic metamorphism 

分 类 号：P618.2[天文地球—矿床学] P588.3[天文地球—地质学]