| 九江—瑞昌地区铜矿床成矿地质特征 |
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| 引用本文：.1988.Geological characteristics of copper metallization in the Jiujiang-Ruichang area, Jiangxi province[J].Mineral Deposits,7(3):15~28 |
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| 中文摘要:本文以江西武山铜矿床为实例，探讨了热液矿床成矿作用某些方面的问题。同熔岩浆同化大量古老基底岩石物质后，侵位至浅层时驱动地下水循环，造成志留系围岩即矿源层的广泛钾硅化蚀变和退色，出现成矿元素近矿地球化学降低场。其中析出的铜质随热液循环系统流经斑岩体中心而被加热蒸发浓集，形成含矿热液，并在有利成矿部位形成不同类型的矿床。文中强调了钾化蚀变在铜质迁移富集和成矿过程中的重要作用，当含矿热液钾离子浓度超过一定值时，铜质又可直接在斑岩体中沉淀形成斑岩铜矿。古铅和古锶同位素、氢、氧和碳同位素组成特征有力支持了这一推论。 |
| 中文关键词:地球化学场 古铅和古锶同位素 环形构造 含矿热液对流循环系统 元素相容性 |
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| Geological characteristics of copper metallization in the Jiujiang-Ruichang area, Jiangxi province |
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| Abstract:The Jiujiang-Ruichang area is located in northwestern Jiangxi, along the western part of the minerogenic belt of middle-lower Yangtze Valley. In this area Ordovician to Triasssic sediments are exposed, and NEE-folds, NW-compressive, NNW-tensile and NEE-compressive-shearing faults make up the major structures. Igneous rocks are mostly intermediate-acid epizonal intrusive bodies(Fig.1). The Wushan copper deposit is a typical one in the area, which consists of skarn-type and stratiform Cu-bearing pyrite-type orebodies. In addition to these types of orebodies, the Chengmenshan copper-molybdenum deposit has porphyry and breccias-pipe type orebodies. Silurian strata, with a great thickness and an average copper content of 51ppm, is considered to be an ore source bed. Around the deposit, there is a copper-decreased field (Fig. 2). The copper which moved out of the decteased field is concentrated in the orebodie. Magmatic rocks that intruded into or near Silurian strata often have relatively high alkali content and K2O/Na2O ratio, and the potash alteration is intensely developed. Maganatic rocks in the area are of co-melting type or mixed type. The magma assimilated a large q‘uantity of country rock substances during its rising. The REE patterns of the magmatic rocks are charac terized by high REE contents, absence of Eu anomalies and high LREE/HREE ratios (Fig.4). Ancient lead and strontium isotope compositions are detected in the feldspar megaphenocryst of the granodiorite porphyry(Table 8, 9). Before the complete cooling of the magmatic system, there existed a huge hydrothermal convective circulation system of magmatic water and supergenic water in the magmatic and country rocks, in which copper, potassium and other ore-forming substances derived from country rocks came into the intrusive body, and then got concentrated through heating, boiling and evaporating. When the ore-forming fluids flowed to the skarn zone or theboundary between Wutong Group and Huanglong Group, the ore-forming substances precipitated as a result of the change in media(Fig.5). If the concentration of Dotassium ion(K+)exceeded the critical value(KCl>9％), copper and other ore substances might have deposited in maganatic rocks, forming porphyry type ore deposits. Finally, this paper makes a metallogenic discriminant analysis of intrusive bodies, characteristic analysis of geological condition, and metallogenic prognosis for some prognostic units. As a result, some ore prospects are indicated. |
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