四川盆地西北缘早-中三叠世界线附近沉积岩地球化学特征及古环境意义

Geochemical characteristics and paleoenvironmental significance of sedimentary rocks near the Early-Middle Triassic boundary on the northwest margin of the Sichuan Basin

ES评分 0

DOI 10.20086/j.cnki.yskw.2023.0204
刊名
Acta Petrologica et Mineralogica
年,卷(期) 2023, 42(2)
作者
作者单位

1. 成都理工大学 地球科学学院, 四川 成都 610059;
2. 内江师范学院 地理与资源科学学院, 四川 内江 641100

摘要
通过分析四川盆地峨眉山地区嘉陵江组-雷口坡组沉积岩元素地球化学及碳、氧同位素特征,探讨了其古环境意义,为四川盆地西北缘早-中三叠世古环境研究提供基础信息。结果表明: 样品∑(CaO+MgO+LOI)为13.98%~93.31%,反映了相对动荡的沉积环境。δ13C值的变化范围是-6.95‰~0.36‰,δ18O值变化范围为-9.06‰~-0.99‰,δ13C值总体表现趋势为降低-升高-降低-升高。海水盐度呈现先升高、后降低、复又升高的多段式变化;海水温度7.11~34.94℃,平均温度21.99℃,古海水温度经历了降低-升高-降低的变化趋势,在早-中三叠世界线附近温度急剧升高。研究区整体处于氧化的沉积环境,间有贫氧的沉积环境出现。以上各个地球化学指标间耦合关系较好,一致反映了研究区早-中三叠世为相对潮湿-相对干热-相对潮湿气候下的海相沉积环境。
Abstract
The elemental geochemistry and carbon and oxygen isotope characteristics of sedimentary rocks from the Jialingjiang Formation-Leikoupo Formation in the Emeishan area of the Sichuan Basin were analyzed to explore their paleoenvironmental significance and provide basic information for the study of the Early-Middle Triassic paleoenvironment on the northwest margin of the Sichuan Basin. The results show that the samples ∑(CaO+MgO+LOI) ranged from 13.98% to 93.31%, reflecting a relatively turbulent sedimentary environment. The data show that the variation range of δ13C value is from -6.95‰ to 0.36‰, and the variation range of δ18O value is from -9.06‰ to -0.99‰. The overall performance trend of δ13C value is decreasing-increasing-decreasing-increasing. The seawater salinity shows a multi-stage change of rising, then decreasing, and then rising again; the seawater temperature ranges from 7.11 to 34.94℃, with an average temperature of 21.99℃, and the ancient seawater temperature experiences a trend of decreasing-increasing-decreasing, with a sharp increase in temperature near the Early-Middle Triassic boundary. The study area as a whole is in an oxidized sedimentary environment, with intermittent occurrences of oxygen-poor sedimentary environments. The above geochemical indicators are well coupled and consistently reflect a relatively humid-relatively dry and hot-relatively humid marine depositional environment in the Early-Middle Triassic boundary of the study area.
关键词
碳酸盐岩;地球化学;古环境;早-中三叠世;四川盆地
KeyWord
carbonate rock; geochemistry; palaeoenvironment; Early-Middle Triassic; Sichuan Basin
基金项目
页码 220-236
  • 参考文献
  • 相关文献
  • 引用本文

李宸,周游,郎兴海*,邓煜霖,王旭辉,何青,李壮,娄渝明,向佐朋,吴伟哲,詹宏宇. 四川盆地西北缘早-中三叠世界线附近沉积岩地球化学特征及古环境意义 [J]. 岩石矿物学杂志. 2023; 42; (2). 220 - 236.

  • 文献评论

相关学者

相关机构