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高校地质学报 ›› 2024, Vol. 30 ›› Issue (02): 231-240.DOI: 10.16108/j.issn1006-7493.2022097

• • 上一篇    

四川盆地及其周缘五峰组—龙马溪组页岩物源及构造环境分析

彭 浩1,陈 雷2, 3*,胡云鹏1,卢 畅2, 4,恒 德1,文 冉1,谭秀成2, 3,秦何星2, 3   

  1. 1. 四川长宁天然气开发有限责任公司,成都 610051;
    2. 天然气地质四川省重点实验室,成都 610500;
    3. 中国石油集团 碳酸盐岩储层重点实验室西南石油大学研究分室,成都 610500;
    4. 中海石油(中国)有限公司深圳分公司,深圳 518000
  • 出版日期:2024-04-20 发布日期:2024-04-20

Provenance and Tectonic Setting Analysis of the Wufeng-Longmaxi Formation Shale in the Sichuan Basin and Its Surrounding Area

PENG Hao1,CHEN Lei2,3*,HU Yunpeng1,LU Chang2,4,HENG De1,WEN Ran1,TAN Xiucheng2,3, QIN Hexing2,3#br#   

  1. 1. Sichuan Changning Gas Development Co., Ltd., Chengdu, 610051, China;
    2. Natural Gas Geology Key Laboratory of Sichuan Province, Chengdu 610500,China;
    3. Branch of Key Laboratory of Carbonate Reservoirs, Southwest Petroleum University, CNPC, Chengdu 610500, China;
    4. CNOOC Co., LTD. Shenzhen Branch, Shenzhen 518000, China
  • Online:2024-04-20 Published:2024-04-20

摘要: 四川盆地及周缘五峰组—龙马溪组页岩在沉积学特征、矿物学特征和地球化学特征等方面均具有较大差异性。而物质来源是决定页岩物质组分、矿物学、脆性等的基础,因此文章基于主量元素、微量元素和稀土元素等数据,对四川盆地及周缘五峰组—龙马溪组页岩的地球化学特征、源岩属性和构造背景进行了分析。结果表明,四川盆地及周缘五峰组—龙马溪组页岩的地球化学组成主要为SiO2、CaO和Al2O3。从川西南—川南—川东南—川东北地区,五峰组—龙马溪组页岩的SiO2含量逐渐增大,CaO含量逐渐减小。La/Yb—ΣREE 图解分析表明,四川盆地及周缘不同地区五峰组—龙马溪组页岩的源岩具有一定的差异性。其中川西南和川南地区五峰组—龙马溪组页岩的源岩属性较为相似,主要为碱性玄武岩、沉积岩和花岗岩,川东南地区以花岗岩和碱性玄武岩为主,川东北地区主要为沉积岩和花岗岩。ICV指数分析显示川西南和川南地区五峰组—龙马溪组页岩均为构造活动的首次沉积,而川东南和川东北地区五峰组—龙马溪组页岩则经历了再循环作用或遭受了强烈的化学风化作用。Sc/Cr-La/Y图解及其他相关参数分析表明四川盆地及周缘五峰组—龙马溪组页岩沉积时期的构造背景均为被动大陆边缘。

关键词: 页岩, 五峰组—龙马溪组, 物源分析, 构造背景, 四川盆地

Abstract: The Wufeng-Longmaxi Formation shales show great variations in sedimentological, mineralogical and geochemical characteristics across the Sichuan Basin and its surrounding areas. Provence and sources are the basis in determining  composition, mineralogy, and brittleness of shale. In this paper, we analyze the geochemical characteristics, source rock properties and tectonic setting of the Wufeng-Longmaxi shale in the Sichuan Basin and its surrounding areas based on major elements, trace elements, and rare earth elements data. The results show that the main components of the Wufeng-Longmaxi shale are SiO2, CaO and Al2O3 in the Sichuan Basin and its surrounding areas. From the southwest to south -southeast -northeast Sichuan, the SiO2 content in the Wufeng-Longmaxi Formation shale increases gradually, while the CaO content decreases gradually. The La/Yb-REE diagram shows that the source rocks of the Wufeng-Longmaxi Formation shale have certain variations in different areas of Sichuan Basin and its surrounding areas. The source rocks of the Wufeng-Longmaxi Formation shales are similar in southwest Sichuan and South Sichuan, mainly consisting of alkaline basalt, sedimentary rocks and granites. The shale source rocks of southeast Sichuan are mainly composed of granite and alkaline basalt, while the shale source rocks of northeast Sichuan are mainly composed of sedimentary rocks and granites. The ICV index analyses reveal that the source of the Wufeng-Longmaxi shales in southwest and south Sichuan is a result of rapid deposition of the first cycle of the near source, while the Wufeng-Longmaxi shales in southeast and northeast Sichuan have undergone recycling or strong chemical weathering. The analyses of Sc/Cr-La/Y diagram and other related parameters indicate that the Wufeng-Longmaxi Formation shale in the Sichuan Basin and its surrounding areas was deposited in a passive continental margin.

Key words: Shale, Wufeng-Longmaxi Formation, provenance analysis, tectonic setting, Sichuan Basin

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