摘要
白拉蛇绿岩位于班公湖—怒江缝合带中段,主要岩石类型为辉长岩、辉橄岩、纯橄岩、玄武岩、辉石岩等。所有基性岩样品富镁,低钛、钠、硅,富集大离子亲石元素(如Rb、Ba、Th等),且亏损高场强元素Ta、Ti等,通过地球化学元素分析认为白拉蛇绿岩形成于俯冲消减带之上(SSZ)的构造环境,很可能是小洋盆发育晚期洋壳进入俯冲消减过程中的产物。在蛇绿岩中获得辉长岩的锆石U-Pb年龄为(189.7±1.3)Ma,表明班公湖—怒江特提斯洋在早侏罗世末构造环境由扩张开始向俯冲消减的转换。
Baila ophiolite is located in the middle of Bangong Lake Nu River suture zone,rocks are gabbro,augite peridotite,dunite,basalt and pyroxenite.All the mafic samples are rich in magnesium,low in Ti,Na,Si,and enriched in large ions,such as Rb,Ba,Th and so on,and depleted in high field strength elements such as Ta and Ti.Through the analysis of geochemical elements that Baila ophiolite formed in the subduction zone(SSZ)tectonic environment,probably is a product of small ocean basin during the late development of oceanic crust into the subduction process.In the ophiolite in zircon U-Pb age of gabbro was(189.7±1.3)Ma,showed that the Bangong Lake Nu River tethys ocean changed from expansion to subduction at the end of Early Jurassic in the tectonic environment.
作者
孔维华
蒋之飞
周新
徐学金
方明
方洁
肖霞
KONG Weihua;JIANG Zhifei;ZHOU Xin;XU Xuejin;FANG Ming;FANG Jie;XIAO Xia(Sixth Geological Brigade of Hubei Geological Bureau,Xiaogan,Hubei432000)
出处
《资源环境与工程》
2017年第6期669-674,共6页
Resources Environment & Engineering
基金
西藏1:5万班戈江错地区H46E002003等6幅区域地质矿产调查项目(项目编号:1212011221082)
