摘要
华南大陆南缘的加里东期构造演化过程尚不清晰,同期岩浆岩研究为探究其构造过程提供了窗口。对云开地块北缘粤西广宁地区花岗闪长岩的野外地质调查和年代学、岩石地球化学研究结果表明,所采样品的锆石LA-ICP-MS U-Pb年龄为(440.1±6.4)Ma和(442.0±8.6)Ma,具有低钾、富钠、贫镁特征。花岗闪长岩富集Rb、Ba等大离子亲石元素,亏损Nb、Ta等高场强元素,总体表现出I型花岗岩的特征。本区花岗闪长岩是由华南大陆陆陆碰撞造山阶段后期伸展环境下岩石圈地幔拆离导致软流圈上涌,使得古老(变)砂岩基底部分熔融形成。
Guangning granodiorite locates in western Guangdong province,at the northern edge of Yunkai block in Cathaysia block.The caledonian tectonic evolution of the South China block is still unclear,and the study of the contemporaneous magmatic rocks can provide information on this problem.Field survey and isotope chronology and geochemistry of Guangning granodiorite have been done in this research.Zircon U-Pb LA-ICP-MS ages of(440.1±6.4)Ma and(442.0±8.6)Ma have been acquired.The rocks show the geochemical characteristics of low K,rich Na and poor Mg,with the enrichment of large ion lithophile elements such as Rb,Ba and Th,and the depletion of high field strength elements such as Nb and Ta,which are consistent with the characteristics of I-type granite.Combined with previous studies,a model is proposed that the South China continent was in the stage of continent-continent collision orogeny after the closure of the proto-Tethys.The Guangning granodiorite is derived from the partial melting of the old sandstone basement,which is triggered by the asthenosphere upwelling after the detachment of the lithospheric mantle in the extensional environment.
作者
邓飞
杨晓聪
DENG Fei;YANG Xiao-cong(Foshan Bureau of Geological Survey,Guangdong Province,Foshan 528000,China;College of Civil Engineering,Tongji University,Shanghai 200092,China)
出处
《东华理工大学学报（自然科学版）》
CAS
2022年第2期101-114,共14页
Journal of East China University of Technology(Natural Science)
基金
中国地质调查局地质调查项目“广东1∶5万凤岗圩、北市、古水、江屯圩幅区调”(1212011120824)。
作者简介
邓飞(1984-),男,硕士,高级工程师,主要从事区域地质调查与工程地质条件评价工作。E-mail:dengfei@tongji.edu.cn。
