沉积与特提斯地质2026，Vol.46Issue(1)：80-93,14.DOI:10.19826/j.cnki.1009-3850.2026.01005
四川盆地西南缘YY1井五峰组—龙马溪组元素地球化学特征及古环境意义
Geochemical characteristics and paleoenvironmental implications of the Wufeng-Longmaxi formations in Well YY1,southwestern margin of the Sichuan Basin
摘要
Abstract
Most outcrops of the Wufeng-Longmaxi formations along the southwestern margin of the Sichuan Basin have been affected by surface weathering,resulting elemental migration that compromises the accuracy of geochemical analyses to some extent.To minimize weathering effects,this study conducted geochemical analysis on organic-rich shales from the Wufeng-Longmaxi formations in Well YY1.Major element analyses reveal that the average concentration of SiO2 in the shale sample is 49.99%,and the average concentration of Al2O3 is 11.78%,both mostly lower than those of the North American Shale Composite(NASC).In contrast,CaO concentrations are higher than those in NASC and in other regions of the Sichuan Basin,exhibiting low SiO2/Al2O3 values and high CaO concentrations.Trace element data exhibit relative enrichment in Th,U,Pb,Nb,Sr,Ba,and Mo,and depletion in Ti,Hf,and Ta.Redox-sensitive proxies indicate that the U/Th ratio ranges from 0.09 to 4.31,δU from 0.44 to 1.86,V/(V+Ni)ratio from 0.53 to 0.88,Ni/Co ratio from 3.02 to 23.29,Th/Mo ratio from 0.07 to 41.00,and MoEF/UEF ratio from 0.2 to 5.58,with clear vertical segmentation.The upper Wufeng Formation to the first submember of Long1 Member(S1ln11)represents weakly reducing to reducing depositional environment conducive to the preservation of organic matter.High V and biological Ba concentrations reflect high paleoproductivity.Simultaneously,the Wufeng-Longmaxi formations were deposited within a paleogeographic framework confined by paleo-uplifts,reflecting restricted water circulation and limited influence from upwelling currents.关键词
元素地球化学/氧化—还原环境/古生产力/五峰组—龙马溪组页岩/四川盆地西南缘Key words
elemental geochemistry/redox conditions/paleoproductivity/the shale of Wufeng-Longmaxi formations/southwestern margin of the Sichuan Basin分类
天文与地球科学引用本文复制引用
林家善,冯伟明,杨平,汪正江,熊国庆,葛祥英,张华英..四川盆地西南缘YY1井五峰组—龙马溪组元素地球化学特征及古环境意义[J].沉积与特提斯地质,2026,46(1):80-93,14.基金项目
中央在川高校院所"聚源兴川"项目(2024ZHCG0183) （2024ZHCG0183）
四川省自然资源厅科技项目(ZDKJ-2025-001) （ZDKJ-2025-001）
中国地质调查局战略性矿产资源调查评价项目(DD20240200503) （DD20240200503）
