| 藏南江孜地区早白垩世甲不拉组钙质超微化石的特征及其地层意义 |
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| 引用本文： | 高莲凤,张振国,姚纪明,左文喆,马亚杰,张鹏,万晓樵.藏南江孜地区早白垩世甲不拉组钙质超微化石的特征及其地层意义[J].地质通报,2012,31(6):907-914. |
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| 作者姓名： | 高莲凤 张振国 姚纪明 左文喆 马亚杰 张鹏 万晓樵 |
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| 作者单位： | 1. 河北联合大学地层古生物研究中心,河北 唐山 063009;现代古生物学和地层学国家重点实验室(中国科学院南京地质古生物研究所),江苏 南京 210008;中国地质大学生物地质与环境地质国家重点实验室,湖北 武汉 430074
2. 中国地质大学(北京)地球科学与资源学院,北京,100083 |
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| 基金项目： | 国家自然科学基金，河北省自然科学基金，现代古生物学和地层学国家重点实验室(中科院南京地古所)项目，河北省高等院校科学技术研究青年基金，中国地质大学生物地质与环境地质国家重点实验室项目 |
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| 摘 要： | 藏南江孜一带的侏罗纪—白垩纪海相地层被划分为维美组和甲不拉组。通过偏光显微镜和扫描电镜观察和分析,发现甲不拉组黑色页岩中含有保存较为完好的钙质超微化石。研究区的生物丰度和分异度偏低,经鉴定以椭圆球石科(Ellip-sagelosphaeraceae)生物群为主,数量相对丰富,但属种比较单调。超微化石指示甲不拉组为早白垩世沉积的产物。结合菊石和双壳类化石,认为甲不拉组地层时代属于早白垩世贝利阿斯期至凡兰吟期(Berriasian-Valanginian)。这一发现标志着西藏特提斯东部早白垩世地层中钙质超微化石的存在。甲不拉组早白垩世钙质超微化石的发现,为该地区海相地层的时代划分、对比提供了新的资料,也为寻找海相侏罗纪—白垩纪地层界线指示了目标。
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| 关 键 词： | 钙质超微化石 甲不拉组 贝利阿斯期至凡兰吟期 西藏南部江孜地区 |
The characteristics of Early Cretaceous calcareous nannofossils from Jiabula Formation in Gyangze area, southern Tibet, and their stratigraphic significance |
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| GAO Lian-feng
,
ZHANG Zhen-guo
,
YAO Ji-ming
,
ZUO Wen-zhe
,
MA Ya-jie
,
ZHANG Peng
,
WAN Xiao-qiao.The characteristics of Early Cretaceous calcareous nannofossils from Jiabula Formation in Gyangze area, southern Tibet, and their stratigraphic significance[J].Geologcal Bulletin OF China,2012,31(6):907-914. |
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| Authors: | GAO Lian-feng ZHANG Zhen-guo YAO Ji-ming ZUO Wen-zhe MA Ya-jie ZHANG Peng WAN Xiao-qiao |
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| Institution: | 1.Research Center of Stratigraphy & Palaeontology,Hebei United University,Tangshan 063009,Hebei,China; 2.State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,CAS),Nanjing 210008,Jiangsu,China; 3.State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,Hubei,China; 4.School of Earth Science and Resources,China University of Geosciences,Beijing 100083,China |
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| Abstract: | The marine Jurassic-Cretaceous boundary strata are outcropped in southern Tibet. The strata in Gyangze area are divided into Weimei and Jiabula Formations. The samples were observed and analyzed by means of polarizing light microscope (PLM) and scanning electron microscope (SEM), and the well-preserved calcareous nannofossils were found for the first time in the black shale of Jiabula Formation along the Jiabula-Gokou section. Biological abundance and diversity are relatively low in the study area. According to the fossil identification the biota discovered is mainly the Ellipsagelosphaeraceae fauna which is abundant with minor variation at the genus and species level. The nannofossils indicate that the Jiabula Formation is a product of Early Cretaceous deposition. Considering the coexistent fossils of ammonites and bivalves, the authors hold that the age of Jiabula Formation is the Berriasian-Valanginian of Early Cretaceous. The significant finding shows that the Early Cretaceous nannofossils occur in the eastern Tethys. The discovery of nannofossils provides new evidence for the age of marine strata and their stratigrphic correlation, and also indicates the possibility of the marine Jurassic-Cretaceous boundary study. |
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