| 安徽金寨银山钼-铅-锌多金属矿床Re-Os和有关岩浆岩40Ar-39Ar年龄测定 |
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| 引用本文：楼金伟,陆三明,谢巧勤,褚平利,尹 滔.2009.Re-Os ages of molybdenum-lead-zinc polymetallic deposits and 40Ar-39Ar ages of related magmatic rocks in Yinshan area, Jinzhai, Anhui Provi nce[J].Mineral Deposits,28(5):621~632 |
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| 基金项目:国家自然科学基金项目（40972063） |
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| 中文摘要:近年，在安徽金寨银山地区，发现了钼-铅-锌多金属矿床，赋矿岩石为中酸性岩浆岩。岩浆岩中的黑云母和角闪石单矿物的40Ar-39Ar同位素地质年龄测定表明，矿区内的中粒二长花岗岩、细粒二长花岗岩和细晶闪长岩脉分别形成于（136.8±1.6） Ma、（130.4±1.2） Ma和（125.4±1.0） Ma，为燕山晚期早白垩世侵入岩。根据岩体产状和接触关系，赋矿石英正长（斑）岩和爆发角砾岩的形成晚于二长花岗岩和细晶闪长岩脉。矿区内，钼矿体和铅锌矿体主要呈脉状产于不同岩性的岩浆岩体中，钼矿体主要发育于爆发角砾岩中心附近的石英正长斑岩中，铅锌矿体则主要赋存在二长花岗岩体中。钼矿床中辉钼矿的Re-Os同位素模式年龄为（112.6±1.3） Ma和（113.5±1.3） Ma。根据矿体与岩浆岩的相互关系以及同位素地质年龄测定，矿区内的钼-铅-锌多金属矿床与石英正长斑岩的形成时间接近，成矿与浅成-超浅成偏碱性岩浆的侵入和相关的热液作用有关，属于斑岩_隐爆角砾岩型矿床。结合前人的研究成果，笔者认为：该区的岩浆岩和钼_多金属矿床形成于中国东部大规模岩石圈减薄、拆沉和热侵蚀的地球动力学背景，大别造山带应力场由挤压转化至伸展阶段以后；区内的钼-多金属矿床归属东秦岭-大别钼成矿带的东延部分，是中国东部EW向大规模成矿带的组成部分。 |
| 中文关键词:地球化学 同位素地质年龄 钼-铅-锌多金属矿床 岩浆岩 银山地区 金寨 安徽 |
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| Re-Os ages of molybdenum-lead-zinc polymetallic deposits and 40Ar-39Ar ages of related magmatic rocks in Yinshan area, Jinzhai, Anhui Provi nce |
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| Abstract:In recent years, molybdenum-lead-zinc polymetallic deposits were discovered in Yinshan area, Jinzhai, Anhui Province. The ore bodies are hosted mainly in Yanshanian magmatic rocks. Dating results of 40Ar/39Ar isotopic ages of biotite and hornblende in magmatic rocks show that medium-grained adamellite, fine-grained adamellite and fine-granined diorite in the ore district were formed respectively in (136.8±1.6) Ma, (130.4±1.2) Ma and (125.4±1.0) Ma, suggesting that they are Early Cretaceous products formed during late Yanshanian movement. According to their attitudes and relationship, quartz-syenite (porphyry) and explosion-breccia were formed later than adamellite and diorite. Regional magmatism evolved from high potassium calcalkaline to alkaline. Molybdenum and lead-zinc deposits occur in the veined form in different lithologic magmatic rocks, and molybdenum deposits mainly occur in quartz syenite (porphyry) distributed in the center of explosion-breccia. The Re-Os isotopic model ages of molybdenite in molybdenum deposits are (112.6±1.3) Ma and (113.5±1.3) Ma, which are considered to be the ages of regional molybdenum deposits. Geological characteristics and isotopic ages show that the molybdenum-lead-zinc polymetallic deposits may genetically related to the emplacement and hydrothermal activities of the late stage quartz syenite (porphyry). These deposits should thus belong to shallow-seated or ultra-shallow-seated porphyry-explosion-breccia deposits. In combination with the achievements made by previous researchers, the authors hold that the molybdenum-lead-zinc polymetallic deposits and related magmatic rocks were formed in a geodynamic setting of regional large-scale lithospheric thinning, delamination and thermal erosion in East China, and also in a regional stress field formed during the conversion of the Dabie orogenic belt to the extension stage. The molybdenum polymetallic deposits are controlled by the EW-trending structures, and belong to the East Qinling-Dabie molybdenum belt, a part of the larger EW-trending metallogenic belt in eastern China. |
| keywords:geochemistry, isotopic age, molybdenum-lead-zinc polymetallic deposit, magmatic rock, Yinshan area, Jinzhai, Anhui Province |
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