| 内蒙古中西部浅变质岩为容矿围岩的金矿床地质特征及形成过程 |
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| 引用本文：.2010.Geological features and genesis of gold deposits hosted by low-grade metamorph ic rocks in central-western Inner Mongolia[J].Mineral Deposits,29(1):58~70 |
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| 基金项目:国家科技支撑项目（2007BAB25B02） |
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| 中文摘要:从地质-构造单元上看，内蒙古中西部位于华北陆台北缘西段，区内浅变质岩为容 矿围岩的金矿床（点）星罗棋布，并且具有重要的经济价值，代表性矿床有常山壕（特大型）、朱拉扎嘎（大型）和赛音乌苏（中型）金矿床。金矿化大都在白云鄂博和渣尔泰裂谷带中元古界砂岩、粉砂岩、碳质板岩、千枚岩和片岩中呈层状、似层状和网脉状产出，并且与古生代侵入 岩脉群具有密切的空间分布关系。研究结果表明，尽管上述3处金矿床所处的地理位置不同，但是它们的产出环境、地质特征和形成机理大体相似，并且可与乌兹别克斯坦穆龙套超大型金矿床相对比。金成矿作用发生的时间与古大陆边缘裂谷带构造-岩浆活动高峰期相吻合，其中海西期构造变形和岩浆侵位所诱发的热液活动是导致金矿床形成的主导控制因素。浅变质岩为容矿围岩的金矿床属中-低温热液金矿床，是地壳特定演化阶段的产物。 |
| 中文关键词:地质学 金矿床 浅变质岩 地质特征 时空分布 成矿作用 内蒙 古中西部 |
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| Geological features and genesis of gold deposits hosted by low-grade metamorph ic rocks in central-western Inner Mongolia |
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| Abstract:The central-western Inner Mongolia area, located in the western section of the northern margin of the North China Craton, is one of the most important gold metallogenic provinces in North China. The gold deposits and prospects hosted by low-grade metamorphic rocks are widely distributed in two parallel EW-trending Proterozoic rift belts, i.e., the Bayan Obo belt in the north, and the Chaiertaishan belt in the south. Up till now, twenty-three ore deposits and prospects have been discovered, of which Changshanhao,Zhulazaga and Saiyinwusu are the largest ones. Gold mineralization occurs in Proterozoic carbonaceous sandstone, siltstone, carbonaceous phyllite, phyllite, slate and schist in the stratoid layer, stratiform, stockwork and veinlike forms. All these gold deposits are characterized by shallow burial, large-size, simple composition and easy mining. Systematic geological investigations indicate that wall rocks of these deposits and prospects vary from place to place, but most of them show an intimate spatial-temporal relation with the Caledonian ductile-brittle fracture zone and the Hercynian intrusive dyke swarm. Geometry of individual ore bodies is mainly controlled by inters tratified fracture zones. All the geological features of the gold deposits hosted by low-grade metamorphic rocks in central-western Inner Mongolia are similar to features of the Muruntau gold deposit in Uzbekistan. The relationship between the regional crustal evolution and gold metallogeny can be summarized as follows: ① Middle Proterozoic stage: tectono-magmatism caused by the intense rifting occurring within the Early Precambrian continent or along its margin resulted in the spatial preparation of gold and other ore-forming materials and formed a number of gold source beds and protores along certain strata; ② Early Paleozoic stage: a number of gold prospects were formed by regional metamorphism and its related hydrothermal event caused by regional tectonic movement and magmatic intrusion, with middle-to-large-sized gold deposits of this stage also identified; ③ Late Paleozoic stage: gold deposits with economic significance are considere d to have been caused by the reworking of the early formed deep-rooted faults and its related Hercynian mafic to felsic magmatism. The extensional faulting and high alkaline magmatism might have played the key role during the formation of the ore deposits. Geological and geochemical features of the gold deposit hosted by the low-grade metamorphic rocks occurring in central-western Inner Mongolia have aroused much attention among geologists both in China and abroad. An integrated analysis of the geological setting and geological and geochemical features of these deposits and their related intrusive rocks will greatly upgrade the understanding of the ore-forming processes of the gold deposits and prospects hosted by low-grade metamorphic rocks in central-western Inner Mongolia. Meanwhile, the genetic model and mineral exploration criteria of these deposits and prospects can also be used during the comprehensive evaluation of the concealed gold deposits hosted by low-grade metamorphic rocks in central-western Inner Mongolia and its neighboring areas. |
| keywords:geology, gold deposit, low-grade metamorphic rocks, geological feature, spatial-temporal distribution, ore-forming process, c entral-western Inner Mongolia |
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