在1∶25万区域地质调查工作的基础上,对出露于泸水—潞西一线花岗岩进行了系统的地球化学研究和精确的成岩年代学研究.岩石的地球化学研究表明,该花岗岩具有高SiO2 (67.15％～76.75％),富碱(Na2O+K2 O=4.96％～7.89％),铝饱和指数(A/CNK)为0.97～1.36(平均值＞1.1)的特征,属S型花岗岩.稀土元素总量(∑REE)为89.46×10-6～294.95×10-6,稀土元素配分曲线呈右倾V字型.微量元素显示了富集Rb、Th、Ce、Sm,亏损Ba、Ta、Nb、Hf、Zr.LA-ICP-MS锆石U-Pb测年结果,显示滇西石缸河—平河地区花岗岩形成于中奥陶世(454.9±3.2Ma、461.6±5.0Ma、473.1±5.9Ma、477.7±56.3和452.3±2.9Ma).综合研究认为该期花岗岩具典型造山带花岗岩特征,岩浆的活动具有多阶段、幕式活动的特征,反映泛非运动晚期岩浆活动.%Based on 1 ∶ 250 000 regional geological survey,petrogeochemistry and diagenetic chronology of granite in Lushui-Luxi area are studied in this paper.Geochemical research of rocks shows that the granite is high of SiO2 (67.15％-76.75％),rich of alkali(Na2O+K2O=4.96％-7.89％)and A/CNK =0.97 -1.36(average value ＞1.1),indicating that the granite is belonged to S-type granite.The ΣREE values range from 89.46× 10 6 to 294.95× 10 6,and the REE pattern models show right oblique feature.Trace elements show enrichment of Rb,Th,Ce and Sm and loss of Ba,Ta,Nb,Hf and Zr.LA-ICP-MS U-Pb dating of zircons indicates that the granite body in Shiganghe-Pinghe area was intruded during the Middle Ordovician(454.9±3.2Ma,461.645.0Ma,473.1±5.9Ma,477.7±56.3 and 452.3±2.9Ma),with post-collisional magmatic activity features.It is considered that the granite of Shiganghe-Pinghe area has granite characteristics of the orogenic belt with a multi-stage and episodic magmatic activity,reflecting the magmatic activity in late Pan-African movement.
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