| 阿拉善东七一山大型萤石矿床萤石钐-钕同位素年龄及地质意义 |
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| 引用本文：.2002.Sm-Nd Isotopic Dating of Fluorite Seperates from Dbngqiyishan Fluorite Deposit, Alxa, Western Inner Mongolia[J].Mineral Deposits,21(1):10~15 |
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| 基金项目:国家自然科学基金项目(编号:40073015)和国家地质调查项目(编号:K1.3.22) |
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| 中文摘要:为了查明东七一山矿床的形成过程,对主矿体中的5件萤石样品进行了钐-钕同位素测定,所获得的等时线年龄为(511±5)Ma和 MSWD 值为0.10。此外，143Nd/144Nd初始比值为0.511760±5（2σ）和εNd（t）为-4.2±0.5（2σ）。依据上述同位素分析数据，同时结合容矿围岩和矿体的地质特征，可以推测，东七一山萤石矿床是加里东期构造-岩浆活动的产物。成矿热液来源与壳源岩浆结晶分异作用有关。该矿床属侵入岩为主岩的中高温热液萤石矿床。 |
| 中文关键词:钐-钕同位素 等时线年龄 萤石 矿床成因 东七一山 |
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| Sm-Nd Isotopic Dating of Fluorite Seperates from Dbngqiyishan Fluorite Deposit, Alxa, Western Inner Mongolia |
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| Abstract:Located at the eastern most part of the Kazakhstanian-Beishan plate, the Dongqiyishan deposit is the largest fluorite deposit with the highest ore- grade in North west China. A great number of quartz-fluorite and fluorite veins, veinlets and stock works occur within the Dongqiyishan porphyric granitoid stock and its metamorphic wall rocks. With a Rb-Sr isochron of ( 649±5 6) Ma , the granitoid stock has been considered as a product of Caledonian igneous activity. Five fluorite samples fro m one of the maiorore bodies of the Dongqiyishan deposit give a Sm-Nd isochronage of ( 511±5 ) Ma with εNd( t) value of ( - 4.2±0.5 ) ( 2σ). As the S m-Nd fluorite age is in agreement with field geological evidence, it is thought to be the ore-forming age of the / Dongqiyishan deposit. The εN d ( t) values of the fluorite separates indicate that the Dongqiyishan deposit might have been for med through the following stages: ( 1 ) remelting of the old continental block , ( 2) differentiation and crystallization of crust- derived mag ma and ( 3 ) emplacement and precipitation of hydro thermal fluids. Moreover, the Sm-Nd age data and εNd( t) values of the fluorite separates also indicate that the major ore- bearing granitoid intrusions and their related ore deposits were formed at a transitional continental margin during Caledonian orogeny. |
| keywords:Sm-Nd isotope, ischron age, fluorite, ore genesis, Dongqiyishan |
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