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现代地质 ›› 2023, Vol. 37 ›› Issue (05): 1264-1281.DOI: 10.19657/j.geoscience.1000-8527.2023.037

• 沉积学 • 上一篇    下一篇

鄂尔多斯盆地西南缘长8油层组物源与古沉积环境恢复:来自岩石地球化学的证据

陈曦1,2(), 肖玲1,2(), 王明瑜3, 郝晨曦4, 王峰5, 唐红南6   

  1. 1.西安石油大学地球科学与工程学院,陕西 西安 710065
    2.陕西省油气成藏地质学重点实验室,陕西 西安 710065
    3.中国石油长庆油田分公司第十采油厂,甘肃 庆城 745100
    4.中国石油长庆油田分公司第二采油厂,甘肃 庆阳 745100
    5.成都理工大学沉积地质研究院,四川 成都 610059
    6.中国石油长庆油田分公司第一采油厂,陕西 延安 716000
  • 收稿日期:2022-07-25 修回日期:2023-04-10 出版日期:2023-10-10 发布日期:2023-11-14
  • 通讯作者: 肖 玲,女,博士,副教授,1981年出生,沉积学专业,主要从事沉积储层地质学研究。Email:xl@xsyu.edu.cn
  • 作者简介:陈 曦,男,硕士研究生,1998年出生,地质工程专业,主要从事沉积储层地质学研究。Email:cx901798@163.com
  • 基金资助:
    国家科技重大专项(2016ZX05056);西安石油大学研究生创新与实践能力培养计划“致密储层差异性及其成因机制-以鄂尔多斯盆地陇东地区长6油层组为例”(YCS22112048)

Reconstruction of Provenance and Paleo-sedimentary Environment of the Chang 8 Oil Layer in the Southwestern Margin of the Ordos Basin: Evidence from Petrogeochemistry

CHEN Xi1,2(), XIAO Ling1,2(), WANG Mingyu3, HAO Chenxi4, WANG Feng5, TANG Hongnan6   

  1. 1. School of Earth Science and Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China
    2. Shaanxi Provincial Key Laboratory of Oil and Gas Accumulation Geology,Xi’an, Shaanxi 710065, China
    3. No.10 Oil Production Plant, PetroChina Changqing Oilfield Company, Qingcheng, Gansu 745100, China
    4. No.2 Oil Production Plant, PetroChina Changqing Oilfield Company, Qingyang, Gansu 745100, China
    5. Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, Sichuan 610059, China
    6. No.1 Oil Production Plant, PetroChina Changqing Oilfield Company, Yan’an, Shaanxi 716000, China
  • Received:2022-07-25 Revised:2023-04-10 Online:2023-10-10 Published:2023-11-14

摘要:

沉积岩的地球化学元素特征记录了重要的沉积和源区构造信息,可用于分析其物质来源及古沉积环境。根据鄂尔多斯盆地西南缘延长组长8油层组14件泥岩及粉砂质泥岩样品地球化学元素分析结果,结合岩心观察资料对其物源及古环境进行系统研究。结果表明,鄂尔多斯盆地西南缘地区长8油层组源区构造背景主要为与大陆岛弧相关的活动大陆边缘,研究区长8油层组物源主要来自于盆地西南缘秦祁褶皱带长英质变质岩、火成岩岩系。结合不同元素丰度、元素比值及沉积标志对古沉积环境的研究结果表明,古气候以半潮湿-半干燥、干热气候条件为主,古温度总体高于15 ℃及延长期平均温度;长8油层组沉积时期整体水深较浅,水体性质以淡水为主,古氧化还原环境为浅覆水下的氧化环境。有利的古环境条件、充足的物源为浅水三角洲沉积体系的发育提供了有利条件。

关键词: 鄂尔多斯盆地, 元素地球化学, 古沉积环境, 物源, 长8油层组

Abstract:

Geochemical characteristics of sedimentary rocks recorded important sedimentary and source region tectonic information, which can be an effective means to understand the provenance and paleo-sedimentary environment.Based on geochemical analysis of 14 mudstone and silty mudstone samples in combination with core logging data, the provenance and paleoenvironment of the Chang 8 oil layer of the Yanchang Formation in the southwestern margin of Ordos Basin have been systematically studied.The main conclusions are as follows: The source region was an active continental margin, and the local source of the Chang 8 oil layer is mainly from the metamorphic and igneous rocks of the Qin-Qi orogenic belt in the southwestern margin of the Basin.Combined with different element abundance and ratios and sedimentary marker, our results show that the paleoclimate was dominated by semi-humid-semi-arid, hot arid climatic conditions, and the paleotemperature was generally higher than 15 ℃ and the average temperature of the Yanchang period.Water depth during the Chang 8 deposition was shallow, the paleosalinity was dominated by freshwater environment.The paleo-redox environment was oxidizing under shallow water.The paleoenvironment conditions and sufficient material source provided favorable conditions for the development of the shallow water deltaic sedimentary system.

Key words: Ordos Basin, elemental geochemistry, paleo-sedimentary environment, provenance, Chang 8 oil layer

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