| 藏南定日剖面晚白垩世菊石和叠瓦蛤类的首次发现:生物地层和古环境意义(英文) |
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| 作者姓名： | JensLEHMANN InesWENDLER JensWENDLER HelmutWILLEMS XiumianHU |
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| 作者单位： | [1]GeosciencesCollection,DepartmentofGeosciences,UniversityofBremen,KlagenfurterStrasse,D-28359Bremen,Germany [2]HistoricalGeologyandPalaeontology,DepartmentofGeosciences,UniversityofBremen,KlagenfurterStrasse,D-28359Bremen,Germany [3]DepartmentofEarthSciences,NanjingUniversity,Nanjing210093,China |
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| 基金项目： | 德国不来梅大学校科研和校改项目;北京市中-德研究促进中心提供经费资助项目;国家自然科学基金 |
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| 摘 要： | 藏南定日遮普惹山剖面主要是Albian 晚期到古近纪海相沉积, Willems 等( 1996 )对岩石地层和沉积微相进行了详细研究,并通过浮游有孔虫研究建立生物地层格架。在与岗巴地区地层对比基础上,该剖面被认为是整个藏南地区白垩纪—古近纪海相地层的标准剖面。2004 年我们与中国、德国同行一道对该剖面上白垩统地层进行再考察,重点对无脊椎动物化石样品进行采集和研究。与西藏大多数白垩纪剖面一样,尽管沉积环境为陆棚环境,该剖面以前却几乎没有菊石和叠瓦蛤类化石的报道,而同样环境下的世界其他地区剖面含有大量的菊石和叠瓦蛤类化石。藏南定日剖面重新调查后发现了少量的菊石和叠瓦蛤类化石。化石数量少一方面是由于灰泥质灰岩和泥灰质灰岩内化石保存状况差,另一方面采样条件也不理想。还有,当时的环境条件可能不利于大多数无脊椎动物类群的生存,这一点或许从大量存在于岗巴群上部的小个体双壳类碎片可以得到证实。尽管获得的化石分散并且保存差,本次研究仍获得了一些有价值的生物地层数据。岗巴群上部发现的化石Calycoceras?,指示其时代为Cenomanian 晚期,随后出现不能鉴定的desmoceratids类的幼体。之上,菊石Forresteria sp.的发现表明岗巴群顶部地层属于Coniacian下部,这被同一地层内发现的其他化石所支?
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| 关 键 词： | 菊石 叠瓦蛤 上白垩统 生物地层学 古环境 定日 西藏 |
FIRST AMMONITE AND INOCERAMID DATA FROM THE UPPER CRETACEOUS OF THE TINGRI SECTION IN SE-TIBET:BIOSTRATIGRAPHICAL AND PALAEOENVIRONMENTAL IMPLICATIONS |
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| JensLEHMANN InesWENDLER JensWENDLER HelmutWILLEMS XiumianHU.FIRST AMMONITE AND INOCERAMID DATA FROM THE UPPER CRETACEOUS OF THE TINGRI SECTION IN SE-TIBET:BIOSTRATIGRAPHICAL AND PALAEOENVIRONMENTAL IMPLICATIONS[J].Earth Science Frontiers,2005,12(2):105-112. |
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| Authors: | Jens LEHMANN Ines WENDLER Jens WENDLER Helmut WILLEMS Xiumian HU |
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| Abstract: | A section in the Zhepure Mountains near Old Tingri in SE-Tibet, ranging from the Upper Albian to Paleogene, was described in detail by Willems et al.(1996).These authors worked on the litho-and microfacies and set up the biostratigraphical framework by planktonic foraminifera. Willems et al.(1996) established their section as a standard for southern Tibet and compared it to the Gamba area. During the 2004 Tibet-expedition of Chengdu University of Technology in China, in co-operation with Bremen and Kiel universities in Germany, the locality was revisited for the purpose of collecting invertebrate fossils. This field-work included only the Upper Cretaceous part of the Tingri section and its invertebrate faunal content. Until today almost no ammonite and inoceramid data existed for this section. This is true for most Cretaceous sections in Tibet, although the Upper Cretaceous succession was interpreted as shelf environment. which in other parts of the world contains rich faunas of these macrofossil groups. The newly discovered continuous record of rare ammonites and inoceramids is probably limited since the preservation in the wacke- and packstones is poor. In addition, sampling conditions were unfavorable and the environmental conditions disadvantageous for most groups of invertebrates, as possibly indicated by larger amounts of small bivalve debris (filaments) in the upper part of the Gamba Group. Although the collected fauna is sparse and poorly preserved, the following biostratigraphical data can be added to the hitherto described microfauna: Calycoceras? from the Upper Gamba Group is Late Cenomanian in age and is accompanied by indeterminable juvenile desmoceratids. Superjacent follows a record of the ammonite Forresteria sp., indicating that this level in the upper part of the Gamba Group belongs to the Lower Coniacian. This supports the finding of Inoceramus (Cremnoceramus) waltersdorfensis? hannovrensis? from the same interval. Anagaudryceras? is an individual ammonite finding from the Zhepure Shanbei or Zhepure Shanpo Formation, corresponding to the Santonian-Maastrichtian part of the succession. |
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| Keywords: | ammonite inoceramid Upper Cretaceous biostratigraphy palaeoenvironment Tingri Maastrichtian Tibet |
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