冈底斯中段扎扎龙矿区闪长岩体锆石U-Pb年代学、岩石地球化学特征及其意义  

Zircon U-Pb Chronology,Geochemical Characteristics and Significance of Diorites in Mining Area of Zhazhalong in Mid-Gangdese

作　　者：魏启荣[1] 刘小念[1] 丁鹏飞[1] 王程[1] 王敬元[1] 孙骥[1] 张小强[1] 卜涛[1] 高满新 

机构地区：[1]中国地质大学资源学院,武汉430074

出　　处：《吉林大学学报（地球科学版）》2015年第5期1405-1417,共13页Journal of Jilin University：Earth Science Edition

基　　金：中国地质调查局地质调查项目(1212011086040)

摘　　要：扎扎龙矿区位于西藏冈底斯中段,隆格尔-念青唐古拉铁、铜、铅、锌、银成矿带之西段。岩石学、LA-ICP-MS锆石U-Pb测年及岩石地球化学特征研究显示：扎扎龙矿区闪长岩体的岩石类型主要为闪长岩,个别为石英闪长岩,其LA-ICP-MS锆石U-Pb年龄为（64.15±0.52）Ma,形成于古新世（E1）早期;闪长岩体属准铝质-过铝质岩石（A/CNK值为0.89～1.06）,具高钾钙碱性系列的特征;稀土元素表现为轻稀土弱富集的右倾斜型,绝大多数（La/Yb）N为1.78～2.08,具弱的负铕异常（δEu=0.65～0.81）;微量元素普遍表现出K、Th元素的富集和Nb、P、Ti元素的强烈亏损。扎扎龙闪长岩体源区为壳幔混合源区,形成于雅鲁藏布江洋高角度俯冲阶段,暗示了印度-亚洲大陆碰撞时间应晚于65 Ma。Zhazhalong area is located in the Middle of Gangdese and also on the west part of Longgeer-Nyainqentanglha Fe,Cu,Pb,Zn,Ag metallogenic belt in Tibet.The petrology,LA-ICP-MS zircon U-Pb dating,and lithogeochemical characteristics show that the main rock type is diorite with individual quartz diorite.The LA-ICP-MS zircon U-Pb age of the diorites is（64.15±0.52）Ma which indicates that the rocks were formed in the Early Paleocene.The diorites are meta-aluminous to per-aluminous（A/CNK date is 0.89-1.06）,and belong to the high-K calc-alkaline series.The characters of REE are right-incline and LREE enrichment（LaN/YbNdate is 1.78-2.08）with weak Eu anomaly（δEu date is 0.65-0.81）.The characters of trace elements are rich in K,Th and depleted of Nb,P,Ti intensively.By synthesis analysis,the origin of the rocks was a mixture of crust-mantle,and they were formed in the subduction of Yarlung Zangbo Oceanic crust.This implies that the time of the collision between India and Asia land should be later than 65 Ma.

关 键 词：闪长岩体 锆石U-PB年代学 岩石地球化学 扎扎龙矿区 冈底斯中段 

分 类 号：P597.1[天文地球—地球化学]