云南文山官房钨矿床花岗岩地球化学特征及其地质意义

Geochemical Characteristics of Granite in the Guanfang Tungsten Deposit of Wenshan,Yunnan Province and Its Geological Implications

对云南官房钨矿床花岗岩的岩石学和地球化学特征进行了分析,结果表明:花岗岩的SiO2、Na2O和K2O的平均质量百分数分别为68.49%、2.38%、4.26%,里特曼指数平均为2.33;微量元素表现为Nb、Ta、Y富集,Sr、Ba显著亏损;稀土元素总量平均为256.09×10-6,稀土元素分配模式为LREE富集型,Eu负异常较明显,δEu=0.62～0.72。矿区花岗岩的主量元素特征表明其具有高钾钙碱性岩特征,属于S型花岗岩;主量元素、微量元素特征一致显示其形成于同碰撞构造环境;稀土元素特征表明其物质来源为壳源。研究还表明,矿区花岗岩中钨的含量是中国花岗岩平均含量的23.7倍,较高的钨丰度有利于官房钨矿床的形成。

Petrologic and geochemical analysis for granites from the Guangfang tungsten deposit of Wenshan, Yunnan Province shows that their average contents of SiO2 ,Na20 and K20 are 68.49% ,2.38%, and 4.26%, respectively. The average Rittmann index is 2.33. Trace elements of Nb, Ta, and Y are enriched while Sr and Ba are depleted. The average value of Y REE is 256.09×10^-6. The REE pattern of Guangfang granites is of the enriched type of LREE with pronounced Eu negative anomalies and δEu = 0.62 - 0.72. It is shown that the granite in Guanfang is characterized by highly-enriched kalium calc-alkaline and belongs to the S-type granite. Major and trace elements imply that the granite in Guanfang was formed in a continental collision tectonic setting. The features of REE indicate that they were derived from the crust. The content of tungsten in the granite is 23.7 times the average content of granite in China. Its high tungsten abundance had accommodated the generation of the Guanfang tungsten deposit in this region.