藏北羌塘地区地层新资料

新的牙形石化石资料证实在羌塘北部地区有泥盆纪查桑组地层，它是该盆地保存的最古老海相沉积地层，羌塘地区中西部广大地区上侏罗统索瓦组顶部产有丰富的以Virgatosphinctes和Aulacosphinctes两属为主的菊石化石，可初步建立5个菊石组合，其中Berriasella和Blanfordiceras菊石的出现使最高海相层位上延至提塘阶顶部或贝利阿斯阶，而圆笠虫(Orbitolina)、似异卷虫（Heterohelix）出现可能反映有海相白垩纪地层的存在，在晚三叠世肖茶卡组中发现有Epigondolella牙形石动物群，这是我国晚三叠世最高位牙形石带又一产地，首次在双湖比隆组油页岩剖面顶部发现产Harploceras sp.菊石化石的层位，时代属早上托阿尔斯（Toarcian）。解决了这一特殊沉积地层单位长期争论的时代归属问题，并指出它与早侏罗世海侵高峰期全球缺氧事件有关。

New Biostratigraphic Data of the Qiangtang Area in the Northern Tibetan Plateau

This paper reports new biostratigraphic data of the Qiangtang area in the northern Tibetan plateau and briefly discusses its significance in marine and continental sedimentary history. The exposed oldest marine strata in this region are the Middle Devonian Chasang Formation. Conodont fossils further confirm a previous conclusion and new outcrops are described. We collected a number of ammonites in the upper part of the Upper Jurassic Suowa Formation in western and central Qiangtang and five ammonites assemblages are established. Especially, the presence of Berriasella sp. and Blanfordiceras sp. indicate that the latest marine strata extend to Tithonian or Berriasian. Scattered orbitolina and special corals are clues that marine Cretaceous maybe exists. The Epigondolella fauna is discovered in the Late Triassic Xiaochaka Formation and is the uppermost conodont zone in Tibet. The ammonite beds were found at the top of the doubtful Shuanghu oil shale section, and all of the fossil specimens belong to Harploceras sp. The age of the oil shale has proved to be early Toarcian and it is related to a global oceanic anoxic event.