| 湖南千里山花岗岩体的Nd-Sr同位素及岩石成因研究 |
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| 引用本文：.1995.Nd-Sr isotopic and petrogenetic studies of the Qianlishan granite stock, Hunan Province[J].Mineral Deposits,14(3):235~242 |
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| 基金项目:地质行业基金资助项目——“柿竹园钨多金属矿床成矿作用”研究成果的一部分 |
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| 中文摘要:本文利用Rb-Sr等时线方法测得第一阶段似斑状黑云母花岗岩、第二阶段等粒黑云母花岗岩和第三阶段花岗斑岩的成岩年龄分别为（152士9）×l06 a、（137士7）×l06 a ~（136士6）×106 a和（131士1）×l06 a。Sr-Nd同位素资料表明各阶段花岗质岩石均基本上源于地壳物质的重熔。与钨多金属矿化有关的似斑状黑云母花岗岩和等粒黑云母花岗岩属同一岩浆体系分异演化的产物，其钕模式年龄(tDM= 2307×l06 a)反映出成岩物质来自早元古宙地层的重熔。与铅，锌一银矿化有关的花岗斑岩的钕模式年龄(tDM= 1284×l06 ~ 1578×l06 a)示意出其成岩物质来自中元古宙地层的重熔。 |
| 中文关键词:Rb-Sr同位素 Nd-Sr同位素 钕模式年龄 花岗岩 柿竹园钨矿床 |
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| Nd-Sr isotopic and petrogenetic studies of the Qianlishan granite stock, Hunan Province |
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| Abstract:The Qianlishan granite stock is genetically associated with the world-famous Shizhuyuan supergiant polymetallic tungsten deposit. Being a composite stock, it consists of a pseudoporphyritic biotite granite body with an area of 5.9 km2, an equigranular biotite granite body with an area of 4.l km2, and granite porphyry dikes. Radiometric dating with Rb-Sr whole rock isochron method was successfully applied to the measurement of various stages of granites in the Qianlishan granite stock, yielding the data (152±9) ×106 a for pseudoporphyritic biotite granite, (137±7) ×106 a for central phase of the equigranular biotite granite body, (136±6) ×106 a for marginal phase of the equigranular biotite granite body, and (131±1) ×106 a for granite porphyry dikes. Initial εNd andεSr values are calculated to be -6.39 to -7.59 and 43.1 to 107.7 for pseudoporphyritic biotite granite, -4.52 to -7.53 and 73.4 to 506.2 for equigranular biotite granite, and -5.17 to -8.64 and 176.6 to 179.1 for granite porphyry. Initial 87Sr/86Sr values of pseudoporphyritic biotite granite, equigranular biotite granite, and granite porphyry are 0. 7088, 0.7187～0.7215, and 0.7168 respectively. These data indicate that all of the granitoid rocks dre derived from the crust. Neodymiurm model ages (tDM) range from 1949 ×106 a to 2632 ×106 a with a mean of 2307×106 a for pseudoporphyritic biotite granite, and 1284×106 a to 1578×106 a for granite porphyry. As equigranular biotite granite was formed through the differentiation of pseudoporphyritic biotite granite magma, there is noreasonable single-stage evolutional model ages for it. The model ages, to some extent, suggest that pseudoporphyritic biotite granite and, possibly, equigranular biotite granite are remelting products of the Lower Proterozoic strata which are generally considered to be the material source of tin and tungsten granites in South China, and the granite porphyry is derived from the Middle Proterozoic strata. Derived from different sources, different granitoid rocks in Shizhuyuan area show remarkable difference in preferentiality for metallogenic elements, i. e. pseudoporphyritic biotite granite and equigranular biotite granite are associated with W-Sn-Mo-Bi-Be mineralizations, whereas granite porphyry is related to Pb-Zn-Ag mineralization. |
| keywords:Rb-Sr whole-rock isochron, Nd-Sr isotopes,granite, polymetallic tungsten deposit, Shizhuyan |
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