| 华南花岗岩型铀矿床的形成与活动大陆边缘陆壳演化的关系 |
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| 引用本文：.1988.The relationships of the formation of granite type uraniijm deposits with the crustal evolution along the active continental margin of South China[J].Mineral Deposits,7(4):43~51 |
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| 中文摘要:我国花岗岩型铀矿床集中产出在华南陆壳成熟度较高的特定部位，其特征是：地壳厚度大(莫霍面深度大于36km)，陆壳增生范围宽(1000km以上)，地壳铀含量偏高，其中沉积壳层平均铀含量为5.69ppm，花岗岩的平均铀含量为10.5ppm。产铀花岗岩体的源岩物质来自地壳，是陆壳多次增生和重熔分异的产物。对花岗岩型铀矿床的物质成分、元素组合及同位素组成的研究表明，成矿物质主要来自地壳岩石，是华南地壳多次活化改造的结果。 |
| 中文关键词:花岗岩型铀矿床 活动大陆边缘 地壳演化 改造型花岗岩 同熔型花岗岩 |
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| The relationships of the formation of granite type uraniijm deposits with the crustal evolution along the active continental margin of South China |
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| Abstract:The granite-type uranium deposits are widespread in South China and possess great economic significance in China. The confinental crust of South China in which the uranium deposits occur has three main features: (1) great Thickness; the Moho surface is more than 36 km in depth; (2) wide continental accretion zone, with its width more than 1000 km; and (3) higher uranium contents: the average uranium content of the sedimentary rocks is 5.69 ppm (619 samples), being 1.71 times that of sedimentary rocks of the world, and the average uranium content of the granite rocks is 10.5 ppm, being 3 times as high as that of the granite rocks of the whole world (3.5 ppm). The geological ages of the granites get younger from nor thwest to southeast, and there occur sequentially Xuefengian, Caledonian-Indo-Sinian, Hercynian-Indo-Sinian, Caledonian-Yanshanian and Indo-Sinian-Yanshanian polycyclic granite bodies. The initial ratios of 87Sr/86Sr for these granites are higher than 0.715. The SiO2 contents and K/Na ratios seem to decrease progressively from northwest to southeast, while the Al2O3 and the total REE contents tend to go up. These features indicate that the uranium ore-forming granites were derived from the upper crust and were the products of the repeated remelting and differentiation of the crustal materials. The granite-type uranium deposits are similar to their host rocks in composition and element association. Their hydrogen and oxygen isotopes fall into the range of connate water in theδDH2O(‰)一δ18OH2O(‰)diagram. In addition, the abnormal initial Pb isotopic composition, disperse δ34S and multiple ore-formig ages are characteristic of this type of uranium deposits. These facts suggest that the ore-forming materials of these deposits are derived from the upper crust and the enrichment of these ore-forming materials results from the repeated mobilization and transformation of the earth' s crust in this area. |
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