南岭成矿带大义山藤山坳锡矿床花岗岩成因及锡成矿作用的指示  

Implications to the Petrogenesis and Sn Mineralization of the Granite in the Tengshan’ ao Sn deposit,the Nanling Metallogenic Belt

作　　者：张遵遵 蔺东永[1] 于玉帅 卢友月 付建明[1,2] 李剑锋 秦拯纬[1,2] 马丽艳 宁勇云[3] 张吉梼 ZHANG Zun-Zun;LIN Dong-Yong;YU Yu-Shuai;LU You-Yue;FU Jian-Ming;LI Jian-Feng;QIN Zheng-Wei;MA Li-Yan;NING Yong-Yun;ZHANG Ji-Tao(Wuhan Center of China Geological Survey(Central South China Innovation Center for Geosciences),Wuhan 430205,Hubei,China;Research Center for Petrogenesis and Mineralization of Granitoid Rocks,China Geological Survey,Wuhan 430205,Hubei,China;The No.418 Geological Team,Hunan Development Bureau of Geology and Mineral Exploration,Loudi 417000,Hunan,China)

机构地区：[1]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [2]中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉430205 [3]湖南省地质矿产勘查开发局418队,湖南娄底417000

出　　处：《华南地质》2022年第3期441-458,共18页South China Geology

基　　金：中国地质调查局花岗岩成岩成矿地质研究中心开放基金课题(PMGR202115);中国地质调查局项目(DD20190154,DD20221689);国家重点研发计划(2018YFA0702700)。

摘　　要：藤山坳锡矿床位于南岭成矿带大义山复式花岗岩体南部,具有大型规模潜力。在详细野外地质调查的基础上,本文以矿区分布的花岗岩为研究对象,进行了系统的岩相学、岩石地球化学、高精度LA-ICP-MS锆石U-Pb定年和Lu-Hf同位素测试。定年结果显示,细粒二云母二长花岗岩锆石U-Pb年龄为146.2±1.6 Ma(MSWD=2.2,n=18),与矿区细粒含斑二云母二长花岗岩年龄(158.2±1.2 Ma)相差约12 Ma,指示区内至少存在两期岩浆活动。矿区花岗岩富Si、Al、K,贫Ca、Mg,稀土元素具有四分组效应,ΣREE低(平均91.0×10^(-6))、δEu值极低(平均0.03),以及高FeO^(T)/MgO值(平均16.8),10000×Ga/Al值(3.3~4.8)>2.6等特征,总体显示为高分异的铝质A型花岗岩。岩石微量元素特征及部分锆石ε_(Hf)(t)值(-3.88~6.54)为正值等表明成岩岩浆具有壳幔物质混合来源的特点,形成于板内伸展构造环境,具有较好的锡多金属成矿潜力。The Tengshan’ao Sn deposit,located in the south of the Dayishan Granitic Complex in the Nanling metallogenic belt,provides large-scale potential.Based on a detailed geological survey,the granites of the mining area have been systematically studied on petrography,geochemistry,zircon U-Pb dating,and Lu-Hf isotope in this paper.The results show that the age of the fine-grained two-mica monzonitic granite is 146.2±1.6 Ma,about 12 Ma away from that of the fine-grained two-mica monzonitic granite (158.2±1.2 Ma) containing phenocryst,indicating that at least two stages of magmatic intrusion have occurred in the mining area The granites have consistent litho-geochemistry characteristics,which are rich in silicon,aluminum,and potassium,poor in calcium and magnesium with a lowΣREE content(average 91.0×10^(-6)),and an REE pattern showing an obvious tetrad effect and a strong negative Eu anomaly (the δEu average is 0.03).A combination of the characteristics of high FeO^(T)/MgO ratios (average 16.8) and the 10000×Ga/Al values (3.3-4.8) above2.6,it is presumed to be the highly differentiated and aluminous A-type granite.The characteristics of trace elements and some of the zircon ε_(Hf)(t) values (-3.88-6.54) are positive,indicating that the diagenetic magma is of mixed origin of crust-mantle materials,and has been formed in an extensional tectonic environment within the plate,which is in favor of the tin polymetallic mineralization.

关 键 词：锆石U-PB定年 藤山坳锡矿 大义山岩体 岩石成因 湘南 南岭成矿带 

分 类 号：P618.44[天文地球—矿床学] P611[天文地球—地质学]