Journal of Palaeogeography（Chinese Edition） ›› 2026, Vol. 28 ›› Issue (4): 1529-1549. doi: 10.7605/gdlxb.2026.057

• GEOCHEMISTRY AND SEDIMENTARY ENVIRONMENTS • Previous Articles     Next Articles

Elemental geochemistry and geological significance of the Lower Cambrian Qiongzhusi Formation shales in southern Sichuan Basin,China

WANG Yuan1,2,4(), CHEN Lei1,2,4(), CHEN Xin1,3, XIONG Min1,2,4, LIAO Chongjie1,2,4, ZHANG Zuyou1,2,4, WEI Fengjie1,2,4, WANG Gaoxiang1,3   

  1. 1 School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
    2 Natural Gas Geology Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu 610500, China
    3 Shale Gas Research Institute, PetroChina Southwest Oil and Gas Field Company, Chengdu 610051, China
    4 Research Branch of Southwest Petroleum University, Key Laboratory of Carbonate Reservoirs,CNPC, Chengdu 610500, China
  • Received:2025-08-03 Revised:2025-10-28 Online:2026-08-01 Published:2026-08-14
  • Contact: CHEN Lei,born in 1985,is a professor,and is mainly engaged in unconventional oil and gas geological research. E-mail: cl211@126.com.
  • About author:

    WANG Yuan,born in 2002,is a master degree candidate,and is mainly engaged in unconventional oil and gas geological research. E-mail: .

  • Supported by:
    National Natural Science Foundation of China(42372173)

川南地区下寒武统筇竹寺组页岩元素地球化学特征及地质意义*

王圆1,2,4(), 陈雷1,2,4(), 陈鑫1,3, 熊敏1,2,4, 廖崇杰1,2,4, 张祖友1,2,4, 韦凤洁1,2,4, 王高翔1,3   

  1. 1 西南石油大学地球科学与技术学院, 四川成都 610500
    2 天然气地质四川省重点实验室, 西南石油大学, 四川成都 610500
    3 中国石油西南油气田分公司页岩气研究院, 四川成都 610051
    4 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, 四川成都 610500
  • 通讯作者: 陈雷,男,1985年生,教授,主要从事非常规油气地质研究。E-mail: cl211@126.com。
  • 作者简介:

    王圆,女,2002年生,硕士研究生,主要从事非常规油气地质研究。E-mail: 。

  • 基金资助:
    *国家自然科学基金项目(42372173)

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Abstract:

The Qiongzhusi Formation in the Upper Yangtze Region is currently a key target for shale gas exploration. To reconstruct the sedimentary paleoenvironment of the Lower Cambrian Qiongzhusi Formation in southern Sichuan Basin,this study takes the Qiongzhusi Formation shales from Well A1 as the research object,and explores the weathering intensity,paleoclimatic characteristics,tectonic setting,and provenance features during their deposition through geochemical analyses of major elements,trace elements,and rare earth elements. The results reveal enrichment of TFe2O3,MgO,and K2O,and depletion of SiO2,Al2O3,and Na2O in major elements. Among trace elements,Mo and Cd are strongly enriched,whereas Sr is significantly depleted. The REE distribution patterns are comparable to those of the upper continental crust,showing a right-inclined “V”shape with LREE enrichment,flat HREE trends,distinct LREE-HREE fractionation,and notable negative Eu anomalies. CIA values range from 48.16 to 69.36(average 64.03),and A-CN-K diagrams indicate moderate chemical weathering under a warm and humid climate. The Th/Sc-Zr/Sc plot suggests a first-cycle sedimentary origin for the shale,with no evidence for significant sedimentary recycling. Provenance diagrams(K2O-Rb,TiO2-Zr,Co/Th-La/Sc,and Th/Sc-Zr/Sc)consistently imply intermediate to acidic felsic igneous sources. Major element discrimination and REE abundances(ΣREE=136.51~297.68×10-6,avg. 189.23×10-6,higher than average continental crust)support a passive continental margin setting. Based on paleoclimatic conditions,provenance characteristics,and tectonic setting,it is inferred that the Lower Cambrian Qiongzhusi Formation shales in southern Sichuan were deposited in a passive continental margin under a warm,humid climate with moderate chemical weathering,predominantly sourced from intermediate-acidic felsic igneous rocks of the Kangdian-Yunnan craton with negligible hydrothermal influence.

Key words: Qiongzhusi Formation, geochemistry, weathering, provenance, tectonic setting, southern Sichuan Region

摘要：

上扬子地区筇竹寺组是目前页岩气勘探的重要层位。为重建川南地区下寒武统筇竹寺组沉积古环境,本研究以A1井筇竹寺组页岩为研究对象,通过主量、微量及稀土元素地球化学分析,探究其沉积期风化强度、古气候特征、构造环境及物源特征。结果显示: 页岩中主量元素呈现出TFe2O3、MgO和K2O富集,SiO2、Al2O3和Na2O亏损; 微量元素中Mo和Cd表现出强烈富集,Sr元素强烈亏损; 稀土元素标准化配分模式与上地壳极为相似,呈现“V”型向右倾斜、轻稀土元素富集、重稀土元素平坦式分布、轻重稀土分异明显、Eu负异常明显的特征; CIA值(48.16~69.36,平均64.03)和A-CN-K图解指示物源区遭受中等强度化学风化作用,指示沉积时期气候温暖、湿润; Th/Sc-Zr/Sc二元图解指示页岩未经历多旋回沉积,不具备沉积再循环特征; K2O-Rb、TiO2-Zr、Co/Th-La/Sc和Th/Sc-Zr/Sc二元图解均指示其源岩为中酸性长英质火成岩; 综合特征主量元素构造判别图解及ΣREE分布特征(136.51×10-6~297.68×10-6,平均189.23×10-6,高于大陆上地壳)指示其主体形成于被动大陆边缘。综合古气候条件、物源特征及构造背景,推断川南地区下寒武统筇竹寺组页岩主体形成于被动大陆边缘,沉积时期化学风化强度中等,气候温暖湿润,物源主要来自于康滇古陆的中酸性长英质火成岩,沉积时受热液影响不大。

关键词: 筇竹寺组, 地球化学, 风化作用, 物源, 构造背景, 川南地区

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