摘要
东昆仑造山带晚古生代—早中生代由于布青山-阿尼玛卿洋的俯冲发育有大量岛弧型花岗岩类。选取东昆北巴隆地区朝火鹿陶勒盖花岗闪长岩体寄主岩和闪长质暗色微粒包体进行了岩相学、LA-ICP-MS锆石U-Pb年代学及地球化学研究。结果表明,岩体寄主岩的结晶年龄为242.3±1.3Ma,暗色微粒包体结晶年龄为241.2±0.8Ma,显示其形成于中三叠世;寄主岩和暗色微粒包体A/CNK值介于0.86~1.06之间,为准铝质-弱过铝质;稀土元素总量分别为119×10^(-6)~170×10^(-6)、189×10^(-6),稀土元素配分模式显示右倾型,具有负Eu异常;岩石富集Rb、Ba、Th等大离子亲石元素,亏损Nb、Ta、Ti等高场强元素,具有弧岩浆岩特征。野外及岩相学特征均显示包体为基性岩浆进入酸性岩浆快速冷凝形成的,为俯冲板片断离导致幔源岩浆上侵形成的岩浆混合作用的产物,是布青山-阿尼玛卿洋俯冲晚期的岩浆记录。
In the East Kunlun orogenic belt (EKOB), a large number of Late Paleozoic-Early Mesozoic granitoids of island arc type are widely distributed due to the subduction of Buqingshan-A’nyemaqen Ocean. In this study, the authors carried out a comprehensive analysis of petrography, geochemistry and LA-ICP-MS zircon U-Pb chronology for host rocks and mafic microgranular enclaves of the Chaohuolutaolegai pluton in the Balong area on the southern margin of the eastern EKOB. The results show that the crystallization ages of host rocks and mafic microgranular enclaves are 242.3±1.3Ma and 241.2±0.8Ma, implying that the pluton was formed in Middle Triassic. The A/CNK ratios of host rocks and mafic microgranular enclaves are 0.86~1.06, suggesting metaluminous-weakly peraluminous type, the ΣREE are 119×10-6~170×10-6 and 189×10-6, the REE patterns show right-oblique characteristics and moderate negative Eu anomalies. The trace element geochemistry is characterized evidently by positive Rb, Ba, Th anomalies and negative anomalies of high strength field elements Nb, Ta, Ti, and shows the characteristics of arc magmatic rocks. The field and petrographic characteristics of the mafic microgranular enclaves show that the rocks were formed by the rapid injection of the basic magma into the acid magma, being the product formed by the magma mingling, and that the underplating of basic magma was caused by the break-off of the subduction slab. The pluton is the magmatic record of the late subduction of Buqingshan-Anemaqen Ocean.
作者
陈功
裴先治
李佐臣
李瑞保
陈有炘
刘成军
陈国超
王旭斌
桑继镇
杨森
邓文兵
CHEN Gong;PEI Xianzhi;LI Zuochen;LI Ruibao;CHEN Youxin;LIU Chengjun;CHEN Guochao;WANG Xubin;SANG Jizhen;YANG Sen;DENG Wenbing(School of Earth Science and Resources/Chang ’an University, Xi’an 710054, Shaanxi, China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, MLR, Xi’an 710054, Shaanxi, China)
出处
《地质通报》
CAS
CSCD
北大核心
2016年第12期1990-2005,共16页
Geological Bulletin of China
基金
国家自然科学基金项目(批准号:41472191
41172186)
高等学校博士学科点专项科研基金项目(编号:20110205110004)
中央高校基本科研业务费专项资金项目(编号:CHD2011TD020
2013G1271091
2013G1271092)
