藏北羌塘中侏罗世沟鞭藻

在藏北羌塘盆地中生界烃源岩成烃母质研究的一块标本中 ,发现了丰富且保存良好的沟鞭藻化石 ,至少包括有 2 1个属、 3 2个种的组合。这个组合以旋沟藻型占统治 ,大量发育栉型孢囊 ( ctenidodinioid) ,尤以 Ctenidodinium combazii居首位 ,其次为 Ellipsoidictyum cinctum和L ithodinia 的种 ,还有 Ctenidodinium continuum,C.ornatum,Gongaulacysta jurassica,Systematophora penicillata,Tubotuberella dangeardii和 Valensiella ampulla等中侏罗世巴统期至卡洛期的常见分子参与。根据组合面貌和属种成分的已知地史分布 ,其时代可确定为巴统期( Bathonian)或可能延至早卡洛期 ( Callovian)。沉积环境为正常盐度的开阔海 ,与欧洲诸海域可以沟通。本文还对 3个重要种进行了系统描述

MIDDLE JURASSIC DINOFLAGELLATE CYSTS FROM QIANGTONG, NORTHERN TIBET

A number of Middle Jurassic samples were collected from the Qiangtong basin of northern Tibet for the study of kerogene and source potential,but one of them happened to find rich and well preserved dinoflagellate cysts.The dinoflagellate assemblage recovered from this sample contains at least 32 species of 21 genera.Dominated by gonyaulacoid type,the assemblage is characterized with rich ctenidodinioid cysts,particularly Ctenidodinium combazii ranked number one,then Ellipidictyum cinctum and species of Lithodinia .In addition,common elements of Bathonian to Callovian of Middle Jurassic such as, Ctenidodinium continuum,C.ornatum,Gonyaulacysta jurassic,Systematophora penicillate,Tubotuberella dangeardii and Valensiella ampulla are also involved in the assemblage.On the basis of the whole aspects and ranges of key species and other taxa recorded previously,the assemblage can be dated as Bathonian,or possibly Bathonian to early Callovian.Suggested by dinoflagellates,the study area was during Middle Jurassic under open sea of normal salinity environment and might connect with European seas.