JOPC ›› 2019, Vol. 21 ›› Issue (5): 757-766. doi: 10.7605/gdlxb.2019.05.051

• LITHOFACIES PALAEOGEOGRAPHY AND SEDIMENTOLOGY • Previous Articles     Next Articles

Sedimentary facies of the Member 1 of the Upper Triassic Yanchang Formation in Zizhou area of Ordos Basin and the development of mouth bar in shallow-water delta

Li Yuan1, Zhang Yuan-Fu1,2, Wang Tong3, Zhang Qing4, Wang Min5, Li Rui-Zhi1, Yuan Xiao-Dong1   

  1. 1 School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;
    2 Institute of Scientific Research,China University of Geosciences(Beijing),Beijing 100083,China;
    3 Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China;
    4 Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company,Xi’an 710018,China;
    5 PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China
  • Received:2018-07-28 Revised:2018-09-11 Online:2019-10-01 Published:2019-09-26
  • Contact: Zhang Yuan-Fu,born in 1979,is an associate professor of China University of Geosciences(Beijing). His research interests are sedimentology,sequence stratigraphy and geophysics. E-mail: zhang.yuanfu@163.com.
  • About author:Li Yuan,born in 1995,is a doctor degree candidate of China University of Geosciences(Beijing). She is mainly engaged in applied sedimentology. E-mail: liyuan95@cugb.edu.cn.
  • Supported by:
    Co-funded by the National Natural Science Foundation of China(No.41572092)and the National Science and Technology Major Projects of China(Nos. 2017ZX05009-002-001,2016ZX05033-003-004)

鄂尔多斯盆地子洲地区上三叠统延长组长1段沉积相和浅水三角洲河口坝发育规律*

李媛1, 张元福1,2, 王桐3, 张庆4, 王敏5, 李睿智1, 袁晓冬1   

  1. 1 中国地质大学(北京)能源学院,北京 100083;
    2 中国地质大学(北京)科学研究院,北京 100083;
    3 中国石化石油勘探开发研究院,北京 100083;
    4 中石油长庆油田分公司勘探开发研究院,陕西西安 710018;
    5 中国石油勘探开发研究院,北京 100083
  • 通讯作者: 张元福,男,1979年生,中国地质大学(北京)能源学院副教授,主要从事沉积学、层序地层学及地球物理研究。E-mail: zhang.yuanfu@163.com。
  • 作者简介:李媛,女,1995年生,中国地质大学(北京)能源学院博士研究生,主要从事应用沉积学研究。E-mail: liyuan95@cugb.edu.cn。
  • 基金资助:
    *国家自然科学基金项目(编号: 41572092)和国家科技重大专项(编号: 2017ZX05009-002-001,2016ZX05033-003-004)联合资助

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Abstract: During the depositional period of the Upper Triassic Yanchang Formation,the Ordos Basin was a large depression basin with gentle slope,shallow water and stable tectonic activity, and is conducive to the formation of shallow-water delta. Through field outcrop observation, it is found that the shallow-water delta was developed in Dalihe section in Zizhou area of the Ordos Basin,and mouth bars were developed in shallow-water delta front deposits. Three upward-coarsening cycles with finer lower part and coarser upper part were observed in the mouth bar, and the thickness of argillaceous interlayers in each cycle increased upward, which indicates that during the formation of the mouth bar, the accommodation space increased upward. We summarized development of mouth bar in shallow-water deltas and believed that the formation of mouth bar is jointly controlled by accommodation space and sediment supply: (1) In the case that the accommodation space is increasing, the formation of mouth bar is determined by the amount of sediment supply. If a certain amount of sediment supply exists, then mouth bars formed in a retrogradation pattern. (2) In the case that the accommodation space is decreasing, the formation of mouth bar is determined by the remaining accommodation space. If the remaining accommodation space exists, then mouth bars formed in a progradation pattern. (3) Mouth bars do not develop if there is no accommodation space. The development of mouth bar in the Member 1 of Yangchang Formation in Zizhou area of the Ordos Basin belongs to the first case.

Key words: shallow-water delta, mouth bar, sedimentary characteristics, controlling factor, accommodation, Ordos Basin

摘要： 鄂尔多斯盆地上三叠统延长组沉积时期为大型坳陷湖盆,具有坡缓、水浅和构造相对稳定的特点,有利于浅水三角洲的形成。通过野外露头观察发现,鄂尔多斯盆地子洲地区大理河剖面三叠系延长组长1段发育浅水三角洲沉积。其中,三角洲前缘沉积中发育河口坝,河口坝内部具明显3期下细上粗反韵律,而且每期河口坝内部具泥质夹层厚度具有向上增加的趋势,指示可容纳空间向上增大。总结了浅水三角洲河口坝发育规律,认为河口坝的形成由可容纳空间与沉积物供给共同决定:(1)在可容纳空间变大的情况下,河口坝的形成由沉积物供应量决定,若有一定量的沉积物供给,则形成具湖侵退积序列的河口坝沉积;(2)在可容纳空间变小的情况下,河口坝的形成由剩余可容空间决定,若有剩余可容纳空间,则形成具湖退进积序列的河口坝沉积;(3)当没有可容纳空间时,河口坝不发育。鄂尔多斯盆地子洲地区延长组长1段河口坝的形成属于可容纳空间变大且有沉积物供给的情况。

关键词: 浅水三角洲, 河口坝, 沉积特征, 控制因素, 可容纳空间, 鄂尔多斯盆地

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