JURASSIC AMMONITES IN ANOXIC BLACK SHALES FROM SEWA AND AMDO,NORTHERN TIBET
JURASSIC AMMONITES IN ANOXIC BLACK SHALES FROM SEWA AND AMDO,NORTHERN TIBET
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发表时间：
2006
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通讯作者：
Yinsuo Jia
中科院分区：
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作者：
Yinsuo Jia
本文研究的菊石化石采集于北纬32°~ 33°之间。11种，经鉴定为Phylloceras sp., dummortieria sp., Dactylioceras cf. directum (Buckman), ？Hildoceras sp., Cleviceras cf. elegans。例如，Cleviceras sp., Polyplectus diides (Zieten),Phymatoceras cf. binodata（巴克曼），Pleydellia cf. aalensis (Zieten), Planammatoceras cf. lepsiusi （Gemmellaro）和erycite sp.。它们中的大多数是首次在中国发现的，它们有更多的地中海或亚地中海亲缘关系。在藏北，菊石提供了从下托瓦良世到阿勒良世的生物地层演替，其间有许多明显的间隙。缺氧黑色页岩分别分布在西瓦底托瓦统和安多以东托瓦统与阿莱尼统的过渡区间。
Ammonite fossils in the present paper were collected from the area between 32°—33°N. and 88°—91° E. of Sewa and Amdo, northern Tibet. 11 species, identified as Phylloceras sp., Dumortieria sp., Dactylioceras cf. directum (Buckman), ?Hildoceras sp., Cleviceras cf. elegans., Cleviceras sp., Polyplectus discoides (Zieten),Phymatoceras cf. binodata (Buckman), Pleydellia cf. aalensis (Zieten), Planammatoceras cf. lepsiusi (Gemmellaro), and Erycites sp., are illustrated and described. Most of them are found in China for the first time, to which more mediterranean or submediterranean affinities have been assigned. The ammonites provide a biostratigraphic succession ranging from the Lower Toarcian to Aalenian in northern Tibet with many obvious gaps. Anoxic black shales are recognized in the basal Toarcian from Sewa, and in a transitional interval between the topmost Toarcian to Aalenian from the east of Amdo, respectively.