花岗岩地质地球化学特征及成因
(1. 中南大学 有色金属成矿预测教育部重点实验室，长沙 410083；
2. 中南大学 地球科学与信息物理学院，长沙 410083)
摘 要: 纳勐铜多金属矿区主要的花岗岩类为黑云母二长花岗岩和钾长花岗岩。岩体w(SiO2)为73.45%~77.46%；K2O/Na2O=0.73~1.40，属于准过铝质至弱过铝质富硅钙碱性系列；岩石稀土总量偏低，明显富集大离子亲石元素，亏损高场强元素，Rb/Sr=0.40~4.00。综合分析表明：纳勐矿区花岗岩岩石成因类型相当于Ⅰ型花岗岩，熔融温度较高，成岩过程与幔源岩浆的底侵作用有关，热的幔源不仅为地壳的部分熔融提供了热量，且与熔融的壳源岩浆发生了混合作用。
关键字: 花岗岩；地质特征；地球化学
granites in NaMeung copper polymetal deposit, Laos
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China；
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China）
Abstract:The outcropped rockbody is mainly biotite monzogranite, potassium granite in the NaMeung copper polymetal deposit, Laos. The main rocks belong to metaluminous to weakly peraluminous high Si calc-alkaline series, with w(SiO2) of 73.45%−77.46%, K2O/Na2O=0.73−1.40. It is obvious that the rocks are enriched in LILE and depleted in HFSE, with relatively low ∑REE contents, Rb/Sr=0.40−4.00. The analysis results show that the rockbody is similar withⅠtype, and its partially melting is in the high temperature. The formation of the granites is related to magmatic underplating. The hot mantle magma not only provides heat for the partial melting of crust, but also causes magma mixing with the crustalderived melts.
Key words: granites; geology characteristics; geochemistry
