摘要
在位于班公湖-怒江结合带中段的那曲县觉翁地区首次发现较完整的蛇绿岩剖面,由下到上见有变质橄榄岩、辉橄岩、堆晶岩、块状辉长岩、岩墙群、碳酸盐岩、枕状熔岩、放射虫硅质岩等,被晚白垩世竟柱山组角度不整合覆盖,在堆晶岩中获同位素年龄值128Ma,从而证实蛇绿岩的时代为早白垩世。这一发现填补了班公湖-怒江结合带中段无完整蛇绿岩剖面的空白,并证实除侏罗纪蛇绿岩外还存在白垩纪蛇绿岩,为班公湖-怒江结合带中段最终闭合时间的确定提供了依据。
A relatively complete ophiolite section has been found for the first time in the Jueweng area, Nagqu County, in the central segment of the Bangong Co-Nujiang junction zone. From below upward the section consists of metaperidotites, pyroxene peridotite, cumulates, massive gabbro, dike swarms, carbonatite, pillow lavas and radiolarian cherts. It is unconformably overlain by the .Late Cretaceous Jingzhushan Formation. Isotopic dating of cumulates yields an age of 128 Ma （by the single-zircon fusion method）, thus verifying that the age of the ophiolite is Early Cretaceous. This finding denies the view that no complete ophiolite section in the central segment of the Bangong Co-Nujiang junction zone and demonstrates that there also exists Cretaceous ophiolite in addition to Jurassic ophiolite. This furnishes evidence for the determination of the final closing time of the central segment of the Bangong Co-Nujiang junction zone.
出处
《地质通报》
CAS
CSCD
北大核心
2006年第6期694-699,共6页
Geological Bulletin of China
基金
中国地质调查局项目《1：25万班戈县幅区域地质调查》（编号：200013000137）成果.
关键词
西藏
班公湖-怒江结合带中段
蛇绿岩
早白垩世
Tibet
central segment of the Bangong Co-Nujiang junction zone
ophiolite
Early Cretaceous
