As an important mélange zone in the Kunlun orogenic belt,the Kangxiwa-Subas-Whalelake belt is regarded as the rem-nant zone of the Paleo-Tethys Ocean,and its formation has been closely monitored by the geological community.A new set of ophi-olites was identified in the belt by LA-ICP-MS zircon U-Pb dating.The authors found that the age of gabbro from the magnesian units in the ophiolite is 270.3±0.7Ma(MSWD=0.65),and the age of pillow basalt is 263.4±7.4Ma(MSWD=1.5),which belongs to the Late Permian and represents the age of ophiolite formation.Based on the analysis of rock geochemical characteristics and regional background, it is considered that the ophiolite was formed in the mid-ocean ridge environment and belongs to the typical MORB type ophiolite.Based on the characteristics of main,trace elements,tectonic setting and isotopic age,the authors hold that the Paleo-Tethys oceanic basin continued to exist at least until Late Permian.%康西瓦-苏巴什-鲸鱼湖混杂岩带作为昆仑造山带一条重要的混杂岩带,通常被认为是古特提斯洋的残存带,其形成时限一直受到地质界的密切关注.在该带新识别出一套蛇绿岩,采用LA-ICP-MS锆石U-Pb测年,获得该蛇绿岩铁镁质单元中辉长岩的年龄为270.3±0.7Ma(MSWD=0.65),枕状玄武岩年龄为263.4±7.4Ma(MSWD=1.5),属于晚二叠世,代表蛇绿岩的形成年龄.通过岩石地球化学特征、区域背景等分析,认为其形成于洋中脊环境,属于典型的MORB型蛇绿岩.结合主量、微量元素特征、构造环境及同位素年龄讨论,认为古特提斯洋主洋盆至少持续到晚二叠世.
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