安徽东顾山钨矿床白钨矿主微量元素和Sr-Nd同位素特征及其对成矿作用的指示  

Trace elements and Sr-Nd isotopes of scheelites:Implications for the skarn tungsten mineralization of the Donggushan deposit,Anhui Province,China

作　　者：聂利青 周涛发[1,2] 张千明 张明[3] 汪龙虎[3] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]合肥工业大学矿床成因与勘查技术研究中心,合肥230009 [3]安徽省地质矿产勘查局327地质队,合肥230011

出　　处：《岩石学报》2017年第11期3518-3530,共13页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2016YFC0600206);国家自然科学基金项目(41320104003;41172086;41172084);安徽省国土资源科技项目(2013-k-1)联合资助

摘　　要：安徽东顾山矿床是长江中下游成矿带长江以北发现的首例大型矽卡岩型钨矿床。该矿床的成矿岩浆岩为黑云母花岗岩,成矿时代为97.22Ma,成矿作用明显不同区内140Ma斑岩型铜金矿床和130Ma玢岩型铁矿床。本文通过对东顾山矿床中矽卡岩阶段和氧化物阶段白钨矿开展EPMA矿物主量元素、LA-ICP MS微量元素分析和Sr-Nd同位素测试分析,对矿床成矿流体的演化和成矿物质来源进行了系统研究。矿床中两类白钨矿稀土元素和Mo^(6+)含量演化特征均指示成矿流体氧逸度逐渐减弱。两类白钨矿的εNd(t)范围为-17.7^-16.2,^(87)Sr/^(86)Sr值为0.70956~0.71113,指示东顾山矿床的成矿物质来自地壳,并由董岭群变质基底提供了部分成矿物质。东顾山矿床与长江中下游成矿带及邻区鸡头山矿床、大湖塘矿床中的白钨矿同位素特征差别较大,指示钨矿床的成矿物质来源除了江南式基底和双桥山群基底外,董岭式基底可以为钨矿床提供成矿物质,因此南钨北移的界限可以越过长江深断裂。The Donggushan tungsten deposit was the first discovery in the north of the Middle-Lower Yangtze Metallogenic Belt （MLYB）. The ore-forming age of the deposit is 97.22Ma, which is quite different of the porphyry copper deposits （~140Ma） or iron deposits （~130Ma） in same area. However, the composition and evolution of ore-forming fluids and minerals enrichment and precipitation study about Donggushan deposit are still very weak. We carried out systematic petrography study of Donggushan deposit. The primary ore mineral in Donggushan skarn-type tungsten deposit, scheelites were analyzed for major, trace, rare earth element （REE） abundance and Sr-Nd isotopes. The scheelites show a strong HREE depletion and the decoupling of LREEs and HREEs. The scheelites can precipitate in two stages, which are skarn stage （Skarn） and oxide stage （Oxide）. From Skarn to Oxide, the Mo6＋ in scheelite is decrease. And negative Eu anomalies are also weak. These show that the ore fluid is gradually reducing. The Sr-Nd isotope characteristic of scheelites from Donggushan deposit is significantly different with south sub-belt in MLYB and Dahutang super-large tungsten deposit. The εNd（t） data and 87Sr/86Sr data of scheelites in Donggushan deposit is in the range of -17.7^-16.2 and 0.70956~0.71113 respectively, indicating the ore-forming material of the deposit from the crust, and the Dongling basement probably provided some ore-forming materials. This is an important reason for tungsten deposits to appear north of the Yangtze River.

关 键 词：长江中下游成矿带 东顾山矿床 矽卡岩型矿床 白钨矿 微量元素 SR-ND同位素 

分 类 号：P597[天文地球—地球化学] P618.67[天文地球—地质学]