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现代地质 ›› 2024, Vol. 38 ›› Issue (01): 230-239.DOI: 10.19657/j.geoscience.1000-8527.2024.009

• 古生物学 • 上一篇    下一篇

渤海湾盆地辽西凹陷古近纪微体化石组合特征及地质意义

姚雅琴1(), 杨纪磊1, 赵都菁1, 齐玉民1, 魏文艳1, 曹洁1, 杨娇娇1, 李国良2   

  1. 1.中海油能源发展股份有限公司工程技术分公司,天津 300452
    2.中海石油(中国)有限公司蓬勃作业公司,天津 300452
  • 收稿日期:2023-08-29 修回日期:2023-12-30 出版日期:2024-02-10 发布日期:2024-03-20
  • 作者简介:姚雅琴,女,硕士研究生,1985 年出生,能源地质与工程专业,主要从事地层古生物分析与研究工作。Email:yaoyq@cnooc.com.cn
  • 基金资助:
    国家科技重大专项子课题(2016ZX05024003-002)

Characteristics and Geological Significance of the Paleogene Microfossil Assemblages in the Liaoxi Sag, Bohai Bay Basin

YAO Yaqin1(), YANG Jilei1, ZHAO Dujing1, QI Yumin1, WEI Wenyan1, CAO Jie1, YANG Jiaojiao1, LI Guoliang2   

  1. 1. Engineering Technology Company, CNOOC, Tianjin 300452, China
    2. Pengbo Operating Company, CNOOC (China) Co., Ltd., Tianjin 300452, China
  • Received:2023-08-29 Revised:2023-12-30 Online:2024-02-10 Published:2024-03-20

摘要:

渤海湾盆地辽西凹陷古近纪中晚期为深水湖泊环境,形成了特殊的古生物化石组合。本文通过研究区钻遇古近系钻井进行详细的古生物对比研究,归纳出该地区微体化石组合特征,建立了5个孢粉藻类化石组合及5个介形类化石组合。在辽西凹陷西部和西北部沙河街组见较深水、叠覆明显的近梯形介形类化石Candona sagmaformisC. postabscissa和具膜管的藻类化石Hystrichosphaeridium tubiferumMembranilarnacia,研究区东营组广泛见深水介形类化石Tianjinia fulgidaBohaicythere sp、Parabohainia elliptica等。这些化石特征揭示了沙河街组至东营组沉积时期深水沉积中心范围逐步扩大,最终沉积中心连成一体。同时,通过大量古生物化石和岩性对比,得出辽西凹陷在沙河街组二段沉积时,存在较大范围的沉积间断,研究区内广泛发育沙河街组三段上亚段。这些认识为该地区古近系地层的划分对比及沉积环境研究提供了有利证据。

关键词: 辽西凹陷, 生物组合, 地层划分, 沉积环境

Abstract:

The deep-water environment in lakes of the middle and late Paleogene in the Liaoxi sag, Bohai Bay Basin, formed a special group of paleontological fossils. In this study, we characterized the microfossil assemblages through investigating the paleontological drilling data in this study area. Five fossil assemblages of pollen algae and five mesomorphic fossil assemblages were established. In the western and northwestern Shahejie Formation, distinct near trapezoidal mesomorph fossils Candona sagmaformis, C. postabscissa, and membrane tube algae fossils Hystrichosphaeridium tubiferidium tubiferi and Membranilarnacia originally formed in deep-water were observed. Moreover, mesomorph fossils Tianjinia fulgida, Bohaicythere sp, Parabohainia elliptica, and others formed in deep-water were widely observed in Dongying Formation. These fossil signatures indicate that the range of sedimentary center in deep water expanded gradually from Shahejie Formation to Dongying Formation, and it connected with the sedimentary centers of the Liaozhong depression in the end. Meanwhile, comparison study of a large number of paleontological fossils and their rock lithology, we concluded that the Liaoxi sag and the low convex zone of Liaoxi sag had a large range of sedimentary breaks when deposited in the second section of Shahejie Formation. Also, the upper subsection of the third section of Shahejie Formation is widely developed. This study provides a strong evidence for the division and comparison of the Paleogene strata in this region, and meanwhile this study enriched the relevant studies on sedimentary environment.

Key words: Liaoxi sag, biological assemblage, stratigraphic division, sedimentary environment

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