Acta Petrolei Sinica ›› 2018, Vol. 39 ›› Issue (8): 902-915.DOI: 10.7623/syxb201808006

• Petroleum Exploration • Previous Articles     Next Articles

The palaeoclimate and paleoenvironment evolution and the development mechanism of high-quality hydrocarbon source rock in Mesozoic,North Carnarvon Basin,Australia

Niu Xing1,2, Yang Xianghua1,2, Yan Detian1,2, Zhuang Xinguo2, Wang Bo1,2, Huo Shenjun1,2, Xu Xiaoming3   

  1. 1. Key Laboratory of Tectonics and Petroleum Resources of the Ministry of Education, China University of Geosciences, Hubei Wuhan 430074, China;
    2. Faculty of Earth Resources, China University of Geosciences, Hubei Wuhan 430074, China;
    3. CNOOC Research Institute Company Limited, Beijing 100028, China
  • Received:2018-03-02 Revised:2018-07-05 Online:2018-08-25 Published:2018-09-04

澳大利亚North Carnarvon盆地中生代气候环境演变与优质烃源岩发育机制

牛杏1,2, 杨香华1,2, 严德天1,2, 庄新国2, 王波1,2, 霍沈君1,2, 许晓明3   

  1. 1. 中国地质大学构造与油气资源教育部重点实验室 湖北武汉 430074;
    2. 中国地质大学资源学院 湖北武汉 430074;
    3. 中海油研究总院有限责任公司 北京 100028
  • 通讯作者: 杨香华,男,1964年12月生,1987年获中国地质大学学士学位,2000年获中国地质大学博士学位,现为中国地质大学(武汉)资源学院教授,主要从事沉积学、储层地质学研究。Email:xhyang@cug.edu.cn
  • 作者简介:牛杏,女,1989年2月生,2013年获中国地质大学(武汉)学士学位,现为中国地质大学(武汉)博士研究生,主要从事沉积学、微体古生物学研究。Email:xingncug@163.com
  • 基金资助:

    国家科技重大专项(2011ZX05030)资助。

Abstract:

The Mesozoic paleoclimate and paleoenvironment of North Carnarvon Basin in Australia were reconstructed based on the numerous microfossil data contained in the Mesozoic strata of this basin as well as sedimentary analysis information. The Mesozoic high-quality source rock development mode was explored by comprehensively analyzing the relevant paleo-geographic background. The research results indicate that the changes in genus-species and relative content of microfossil assemblages in different Mesozoic strata correspond to the transition of paleoclimate and paleoenvironment. The paleoclimate presented a cyclic variation of arid-humid-arid-humid; water regression occurred in Early Triassic-Middle and Late Triassic, while a transgression process occurred generally from Late Triassic to Late Cretaceous. Four sedimentary facies were identified in Mesozoic:delta facies, littoral facies, restricted marine facies and open marine facies. The Early Triassic was dominated by open marine facies, and delta facies was mainly developed in the Middle-Late Triassic. Restricted marine facies was particularly developed in Jurassic Period, while Cretaceous period was dominated by restricted marine facies and open marine facies. The microfossil assemblage characteristics of four sedimentary facies were obviously different. The sporopollen content gradually declined in the sequence of delta facies, littoral facies, restricted marine facies and open marine facies, while the content of dinoflagellates plus acritarchs gradually increased. Delta facies and littoral facies were both dominated by sporopollen, while the sporopollen content of restricted marine facies was equivalent to the content of acritarchs and dinoflagellate; open marine facies was dominated by acritarchs and dinoflagellate. The paleoclimate and paleoenvironment had an important influence on the supply of sediments and the production of organic matter, and the microfossil assemblage determined the parent type of organic matter. Both finally determined the development model of organic matter in the basin. According to the paleo-geographic settings and paleoclimate conditions of Mesozoic source rocks as well as the characteristics of microfossil assemblage, the development model of organic matter was concluded into two models, i.e., the development model of terrestrial organic matter under the background of large delta and that of mixed organic matter under the background of restricted marine facies.

Key words: microfossil, palaeoclimate and paleoenvironment evolution, development model of organic matter, Mesozoic, North Carnarvon Basin

摘要:

利用地层中包含的大量微体化石,结合沉积学分析,恢复了澳大利亚North Carnarvon盆地中生代的古气候与古环境,综合中生界优质烃源岩发育的古地理背景,探讨了其发育模式。研究结果表明,中生代不同层段微体化石属种及其相对含量的变化,对应于古气候与古环境的变迁;古气候呈干旱-湿润-干旱-湿润的旋回性变化;早三叠世-晚三叠世为水退过程,晚三叠世-晚白垩世整体为水进过程。中生界可识别出4个沉积相类型:三角洲相、滨海相、局限海相和开阔海相。早三叠世主要发育开阔海相,中-晚三叠世则主要发育三角洲相,侏罗纪局限海相尤为发育,白垩纪主要发育局限海相和开阔海相。4个沉积相的微体化石组合特征差异明显,三角洲-滨浅海-局限海-开阔海孢粉含量逐渐下降,沟鞭藻+疑源类含量逐渐升高;三角洲相与滨浅海相孢粉占主导地位,局限海相孢粉含量与沟鞭藻+疑源类含量相近,开阔海相则以沟鞭藻+疑源类占主导地位。古气候与古环境影响沉积物的供给及有机物的形成,微体化石组合决定了有机质的母质类型,两者最终决定了盆地有机质的发育模式,综合中生界烃源岩发育的古地理背景、古气候条件及微体化石组合特征,将其有机质发育模式总结为大型三角洲背景下陆源有机质发育模式和局限海背景下混合有机质发育模式。

关键词: 微体化石, 古气候与古环境演变, 有机质发育模式, 中生代, North Carnarvon盆地

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