内乌肯菊石Neuqueniceras在西藏的发现及其由“始中央大西洋”向东的迁移

古生代末形成的联合古陆于中生代早期在其东部沿印度河—雅鲁藏布江一线再次分裂,形成了古陆东端新的特提斯洋;而在古陆西端的中部,大约是在中侏罗世的阿连期或早巴柔期,介于南美和北美大陆之间的中央大西洋扩张脊变得活动起来,导致联合古陆南、北向的分裂,在其开裂初期的前裂谷阶段,始中央大西洋以陆表海形式出现,构成了连接东太平洋和西特提斯洋生物群相互交流的海路通道。其水体的深度以及生物群的交流明显受全球海平面变化的制约,这在中侏罗世东太平洋安第斯生物区特有的生物群沿这条海路向特提斯扩散的幅度和范围上得到体现。安第斯生物区特有的菊石属——内乌肯菊石（Neuqueniceras）在我国西藏南部的首次发现表明,在中卡洛期海平面上升达到高峰期时,安第斯生物群沿始大西洋走廊向东迁移和扩散远达特提斯东端的藏南聂拉木地区。

A New Record of Neuqueniceras in Nyalam Area, South Tibet, and Its Migration Through Hispanic Corridor from Andean Province to East Tethys

The east part of Pangea which had formed by the end of Paleozoic broke along Indus-Yarlungzangbo River, and the East Tethys once existed during the Early Mesozoic, while in the west Pangea the Hispanic Corridor occurred due to the activity of the proto - central Pacific Ridge about in Aalenian and Bajocian time. Through the seaway (Hispanic corridor) Neuqueniceras, a Middle Jurassic ammonite peculiar to the Andean province of East Pacific, mi-grated eastward to East Tethys, coinciding with the maximum of middle Jurassic sea levels. It is the first time to document that the migration of the Andean fauna spread into the Nyalam area of Tethys Himalaya.