论文部分内容阅读
西藏喜马拉雅格米格地区的三叠系-侏罗系界线地层的菊石类和双壳类曾生活在热带浅海环境.建立在菊石带基础上的高分辨率地层可用于确定一些动物群的发生.双壳类Aguilerella和Ctenostreon展现了泛热带迁移的模式,它们首先出现在喜马拉雅,然后向东迁移到东南太平洋;这一模式同样为菊石类Choristoceras,Discamphiceras,Pleuroacanthites和Psiloceras calliphyllum的地理分布所支持.一些在其他地方晚三叠世业已绝灭的属种,如菊石类有Choristoceras和Eopsiloceras,双壳类有Newaagia,Terquemia,Persia,Ryderia guangdongensis和Cultriopsis angusta,在西藏喜马拉雅地区却延续到早侏罗世早期.这一现象表明西藏喜马拉雅地区可能在晚三叠世的生物大绝灭过程中起到了避难所的作用.
The ammonites and bivalves of the Triassic-Jurassic boundary strata in the Himalayan Mi-mig area of Tibet have lived in tropical shallow-sea environments and high-resolution formations based on ammonites can be used to identify some fauna The bivalve Aguilerella and Ctenostreon show patterns of pan-tropic migration that first appeared in the Himalayas and then migrate eastward to the southeast Pacific; this pattern is also geographically distributed for the Choristoceras, Discamphiceras, Pleuroacanthites and Psiloceras calliphyllum Some other genera that have been extinct in the Late Triassic elsewhere, such as the ammonites Choristoceras and Eopsiloceras, the bivalves Newaagia, Terquemia, Persia, Ryderia guangdongensis, and Cultriopsis angusta, extend to early Himalayas in Tibet This phenomenon indicates that the Himalayan region of Tibet may play a role as a sanctuary during the extinction of the Late Triassic.