| 碱交代作用及其与钨矿化的关系——主要以西华山钨矿为例 |
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| 引用本文：.1987.The Relationship Of Alkaline Metasomatism To Tungsten Metallization In Xihuashan, Jiangxi Province[J].Mineral Deposits,6(2):29~39 |
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| 中文摘要:西华山存在两种不同性质的碱交代作用。一种以钠长石化和白云母化为主，封闭式地呈面型存在于花岗岩体中，一种以钾微斜长石化（红长石化）和云英岩化为主，开放式地呈线型存在于矿脉两旁。两者与花岗岩之间在特征和成分上的连续性和相关性说明导致碱交代的流体主要源自岩浆。对赣南和湘南、西华山和大龙山以及西华山南区和北区的比较观察，显示在岩浆作用、碱交代作用和成矿作用之间存在共同演化之现象，似乎随着地质环境及岩石组合的变化，钨、锡、钼等成矿元素也有不同的组合趋势。研究表明，成矿作用是岩浆作用、碱交代作用等统一过程的结果，且本质的成矿作用是岩浆。 |
| 中文关键词:花岗岩 碱交代 钨 锡 钼 西华山 |
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| The Relationship Of Alkaline Metasomatism To Tungsten Metallization In Xihuashan, Jiangxi Province |
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| Abstract:The alkaline metasomatism in Xihuashan may be divided into two major types: 1. Early stage alkaline metasomatism. It occurs in the granite in closed and planar forms and is characterized by alkaline feldspathization and muscovitization. Alkaline feldspar and muscovite are spatially linked up with each other, and seem to have bee] formed almost simultaneously. As a result, the granite has been leucocratized and garnetized. Of all the granites in Xihuashant, the leucogranite seems a product of the early stage alkaline metasomatism, whose REE pattern exhibits a leftward declined curve with a strong negative Eu anomaly, similar to REE patterns of aplite, red feldspatbized rock and inner-microclinized rock (Fig.l), suggesting the effect of alkaline metasomatism. 2. Late stage alkaline metasomatism. It occurs alongside the veins in open and linear forms and is represented by red-feldspathization and greisenization which are separate in space but contemporaneous in time. The comparison between south mine and north mine of Xihuashan tungsten deposit, between the Xihuashan and the Dalongshan deposit and between deposits in southern Jiangxi and those in southern Hunan shows that, with the changes in geological environment, such geological parameters as magma association, assemblage of early stage alkaline metasomatized rocks, assemblage of late stage alkaline metasomatized rocks and ore association display correlative evolution. The tungsten content of some rocks in Xihuashan (Table 5) furnishes some special information for the relationship between alkaline metasomatism and tungsten mineralization. 1. The granite at depth, having experienced only slight metasomatism by the early stage alkaline metasomatism, contains <5 ppm tungsten while the granite in upper part of the stock, which underwent intense metasomatism by the early stage alkaline metasornatism, contains 42-54 ppm 2. The fine-grained granite in the upper part of the stock possesses 20-60 ppm tungsten, whereas that at depth <1 ppm. 3. From top to bottom, the W content in red-feldspathized rocks gradually decreases from 190 ppm to 1.2 ppm. Wolframite occurs sporadically in red-feldspathized rocks at the upper part of the stock and ubiquitously in inner-microclinized rocks. All the above facts point to a conclusion that the tungsten had migrated and concentrated at the cupola before alkaline metasmatism. Therefore, although there might exist some relationships between tungsten mineralization, magmatism must have played a dominant part in tungsten concentration. |
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