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| 云南大坪金矿白钨矿微量元素、稀土元素和Sr-Nd同位素组成特征及其意义 | |
| 引用本文： | 熊德信[,] 孙晓明[,] 石贵勇 王生伟 高剑锋 薛婷.云南大坪金矿白钨矿微量元素、稀土元素和Sr-Nd同位素组成特征及其意义[J].岩石学报,2006,22(3):733-741. |
| 作者姓名： | 熊德信[ ] 孙晓明[ ] 石贵勇 王生伟 高剑锋 薛婷 |
| 作者单位： | 1. 中山大学地球科学系,广州,510275;广东省肇庆学院,肇庆,526061 2. 中山大学地球科学系,广州,510275;南京大学成矿作用国家重点实验室,南京,210093 3. 中山大学地球科学系,广州,510275 4. 南京大学成矿作用国家重点实验室,南京 |
| 基金项目： | 科技部科研项目;中国科学院资助项目;教育部跨世纪优秀人才培养计划 |
| 摘 要： | 利用ICP-MS和同位素质谱分析了大坪金矿含金石英脉中白钨矿的微量元素、稀土元素和Sm-Nd、Rb-Sr同位素组成,结果显示大坪白钨矿中富Sr、Ba,而亏损Mo、Bi、Sn、Nb、Ta等,指示原始成矿流体与岩浆的结晶分异作用无关,并非前人普遍认为的岩浆水和大气降水的混合流体;样品的REE球粒陨石标准化配分曲线为高度一致的右倾和MREE富集型,Eu出现正异常,表明白钨矿与流体之间REE元素发生了强烈分异,白钨矿中REE的配分行为主要表现为REE^3＋与Na^＋成化合价补偿形式替代Ca^2＋选择性进入白钨矿晶格中,成矿流体是相对封闭的高温、富Na^＋的还原性热液体系;Sr-Nd同位素组成显示本区原始成矿流体主要来自下地壳,但不排除有幔源物质加入.原始成矿流体的形成与区域性剪切带的活动有关,韧性剪切作用导致下地壳富CO2流体上升,并与闪长岩发生强烈的水岩反应,而剪切带中脆性断裂的形成是成矿流体迁移、集中、沸腾和矿质沉淀的触发因素. |
| 关 键 词： | 白钨矿 微量元素 稀土元素 Sr-Nd同位素 成矿流体 闪长岩 大坪金矿 |
| 文章编号： | 1000-0569/2006/022(03)-0733-41 |
| 收稿时间： | 12 1 2005 12:00AM |
| 修稿时间： | 02 24 2006 12:00AM |
Trace elements,rare earth elements(REE)and Nd-Sr isotopic compositions in scheelites and their implications for the mineralization in Daping gold mine in Yunnan province,China. |
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| XIONG DeXin,SUN XiaoMing,SHI GuiYong,WANG ShengWei,GAO JianFeng,XUE Ting.Trace elements,rare earth elements(REE)and Nd-Sr isotopic compositions in scheelites and their implications for the mineralization in Daping gold mine in Yunnan province,China.[J].Acta Petrologica Sinica,2006,22(3):733-741. | |
| Authors: | XIONG DeXin SUN XiaoMing SHI GuiYong WANG ShengWei GAO JianFeng XUE Ting |
| Institution: | 1. Department of Earth Science, Sun Yat-sen University, Guangzhou 510275, China ;2. Zhaoqing University, Zhaoqing 526061, China; 3. State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanfing 210093, China |
| Abstract: | Scheelite is a widely-distributed accessory mineral in auriferous quartz veins in Daping gold deposit,China.Trace elements,rare earth elements(REE)and Nd-Sr isotopic compositions of the scheelite were determined respectively by ICP-MS and mass spectrograph in this work.The results show that the scheelite is enriched with Sr,Ba and depleted with Mo,Bi,Sn,Nb and Ta, indicating that primitive ore-forming fluid of the Daping mine probably didn't derive from magmatic crystallization and differentiation, and was not a mixed fluid of magmatic and meteoric water proposed by many previous researchers.The scheelites picked from different samples possess very similar MREE-enriched and dextral-inclined chondrite-normalied patterns and positive Eu anomaly,suggesting that intensive REE differentiation occurred between the scheelites and the ore-forming fluid,REE were substituted in Ca~(2+) site of the scheelites by charge compensation mechanism(REE~(3+)+Na~+=2Ca~(2+)),and the primitive ore-forming fluid was a relative high temperature,Na~+ enriched and reducing hydrothermal system.High correlation of trace elements and REE compositions in scheelites and diorite around rocks and their alterations suggests that relative intensive fluid-rock interaction occurred before the scheelites precipitation.Sr-Nd isotopic composition of the scheelites indicates the primitive mineralizing fluid derived predominantly from the lower crust,but interfusion of the mantle-derived fluid could not be excluded.The primitive mineralizing fluid had close relationship with the regional ductile deformation in the mining district,the ductile shear zone penetrated the crust,induced CO_2 enriched fluid ascended from the lower crust,and gave birth to intensive fluid-rock interaction with the diorite rock.Formation of the brittle fractures in the shear zone triggered transportation,concentration and boiling of the ore-forming fluid and precipitation of the ore minerals. |
| Keywords: | Scheelite Trace elements REE Nd-Sr isotopic compositions Ore-forming fluid Diorite Daping gold mine |
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