| 大水式金矿床稳定同位素、稀土元素地球化学研究 |
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| 引用本文：.2000.REE geochemistry and implications of stable isotopes in Dashui type gold deposits[J].Mineral Deposits,19(1):37~45 |
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| 基金项目:原地质矿产部定向科研资助（编号：直科定96-20） |
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| 中文摘要:大水式金矿床是近年来在西秦岭地区发现的一个国内外十分罕见的金矿类型，具有极为独特的矿化特征。通过对矿区热液方解石、硅质岩矿石、硅化灰岩及原岩、岩浆岩等地质体碳-氧、硅-氧、碳-氢-氧同位素和稀土元素地球化学特征的系统研究揭示，成矿物质中碳为氧化作用改造的深成岩浆碳，硅具深部岩浆或岩浆热水来源的特点，成矿流体具岩浆水与建造水混合之特点，各种矿石稀土配分曲线和δEu、δCe值均与岩浆岩类似或接近而与地层灰岩差别较大，从而说明大水式金矿床成矿物质来源与岩浆活动有关，成岩成矿作用具相同渊源和地质构造背景。 |
| 中文关键词:大水式金矿 REE 硅-碳-氧-氢同位素 肃西倾山地区 |
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| REE geochemistry and implications of stable isotopes in Dashui type gold deposits |
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| Abstract:Dashui type gold deposit, a new type of deposits recently discovered in west Qinling orogenic belt, has very unique ore-form ing characteristics. A system atic study of C-H-O-Si is otopes and REE geochemistry of various geological bodies in the ore district was carried out by the authors. The carbon might have been derived from deep magmatic resources. Silicon isotopes are quite similar to those in magma or magmatic hydrothermal solutions. δ30Si values are comparatively low in jasperoid and relatively high and concentrated in siliceous rocks. C-H-O system of fluid inclusions shows that the ore-forming fluid is a mixture of magmatic water and connate water. Calcite and various altered rocks have moderate ∑REE values, which are highest in magmatic rocks and lowest in limestone. ∑LREE/∑HREE ratios of all samples are higher than l. ∑REE, ∑LREE and ∑HREE tend to increase with the intensification of mineralization. Magmatic rocks show weak to moderate negative anomalies of Eu but have no anomalies of Ce, while limestone exhibits obviously positive anomalies of Eu and negative anomalies of Ce. The REE distribution patterns, δEu and δCe in varied ores are close to those in magmatic rocks but quite different from those in limestone. Thus, both stable isotopes and REE geochemistry indicate that the ore-forming materials mainly came from deep sources closely related to Yanshanian tectono-magmatism, and the shallow tectonic activities, magmatic intrusion or volcanism and hydrothermal eruptions were probably a series of evolutionary products of the regional crust during Yanshanian collisional orogeny. |
| keywords:Dashui type gold deposit, REE, Si-C-O-H isotopes, genesis of ore deposit, Xiqingshan area of Gansu P rovince |
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