摘要
赣东北新元古代蛇绿混杂岩带地处于扬子板块南端,江南造山带北东段。本项研究对樟树墩5块玄武岩、西湾3块辉长岩样品进行了系统的地球化学测试,探讨该地区新元古代蛇绿混杂岩中辉长岩和玄武岩成因及构造动力学背景。LA-ICP-MS锆石定年的结果为983±5Ma,其中赣东北蛇绿混杂岩中的辉长岩形成于新元古代。岩石地球化学测试分析表明,赣东北樟树墩、西湾蛇绿混杂岩中的辉长岩具有低K、Mg,中等Ti,高Na、Al等特征,富集大离子亲石元素Rb、Ba、K、Nd、Pb,相对亏损Nb、Sr高场强元素,δEu变化范围在0.84~1.13之间,没有或有弱的Eu异常。赣东北蛇绿混杂岩的辉长岩是原岩经过部分熔融形成的、基性岩成分具有MORB的特征,同时兼具拉斑玄武岩的特征、其后期受到板块俯冲引起的流体交代作用影响。
The Neoproterozoic ophiolite mélange belt in northeast Jiangxi is located at the southern end of the Yangtze plate and the northeast of the Jiangnan orogenic belt.This study makes an approach to genesis and tectonic setting on the basis of analyses of 5 basalt samples from Zhangshudun and 3 gabbro samples from Xiwan.The LA-ICP-MS zircon U-Pb ages are 983±5 Ma.The gabbro in the ophiolite mélange was emplaced in the Neoproterozoic.The analyses show the gabbro with low K,Mg,medium Ti,features such as high Na,Al,the enrichment in large ion lithophile elements such as Rb,Ba,K,Nd,Pb,relative depletion in high field strength elements such as Nb and Sr withδEu values ranging from 0.84 to 1.13.The gabbro of the ophiolite mélange was formed by partial melting of MORB and tholeiite and was influenced by fluid metasomatism during plate subduction.
作者
任雪斌
李学森
REN Xue-bin;LI Xue-sen(College of Earth Sciences,Guilin University of Technology,Guilin,Guangxi541004)
出处
《四川地质学报》
2020年第3期364-370,共7页
Acta Geologica Sichuan
基金
国家自然科学基金(RZ 18100618)
科学发展基金(RZ 18102683)。
关键词
赣东北
蛇绿混杂岩
辉长岩
玄武岩
锆石年代学
地球化学
northeast Jiangxi
ophiiolitic mélange
gabbro
basalt
geochemistry
zircon chronology
