四川盆地东部地区早中三叠世蒸发岩的锶同位素特征及其地质意义

锶同位素已经成为全球海平面变化、造山运动、古气候和古环境等全球地质事件研究与对比的有效工具之一。本文以四川盆地东部地区早中三叠世蒸发岩的野外剖面和钻孔岩心为主要研究对象，测试了碳酸盐岩、硫酸盐岩和石盐岩的锶同位素组成，并建立了相应的锶同位素演化曲线。研究结果显示，碳酸盐岩的⁸⁷Sr/⁸⁶Sr值平均为0.707 895,硬石膏岩的⁸⁷Sr/⁸⁶Sr值平均为0.708 174,石盐岩的⁸⁷Sr/⁸⁶Sr值平均为0.708 177,同时碳酸盐岩的⁸⁷Sr/⁸⁶Sr值从早三叠世的0.707 413快速增加到中三叠世早期的0.708 515,而后呈现下降趋势。从总体上看，这些⁸⁷Sr/⁸⁶Sr值与全球早中三叠世同期的⁸⁷Sr/⁸⁶Sr值数据接近，说明四川盆地东部地区早中三叠世钾盐的物质来源大部分为海水，并沉积于海相沉积环境，同时由于火山...

Characteristics of strontium isotope and the significance for the evaporites of Early and Middle Triassic in the eastern region of Sichuan Basin

Strontium isotopes have become one of the effective tools for studying and comparing global geological events such as global sea level changes, orogeny, paleoclimate, and paleoenvironment. This article takes the field profiles and drilled cores of Early and Middle Triassic evaporites in the eastern region of Sichuan Basin as the main research objects, tests the strontium isotope compositions of carbonate rocks, sulfate rocks, and halite rocks, and establishes the corresponding strontium isotope evolution curves. The results show that the average ⁸⁷Sr/⁸⁶Sr value of carbonate rocks is 0.707 895, the average ⁸⁷Sr/⁸⁶Sr value of anhydrite rocks is 0.708 174, and the average ⁸⁷Sr/⁸⁶Sr value of halite rocks is 0.708 177, and the ⁸⁷Sr/⁸⁶Sr value of carbonate rocks increased rapidly from 0.707 413 in the Early Triassic to 0.708 515 in the early Middle Triassic, and then showed a downward trend. Overall, the ⁸⁷Sr/⁸⁶Sr values are close to the published global ⁸⁷Sr/⁸⁶Sr data of the same period in the Early and Middle Triassic, indicating that the material source of the Early and Middle Triassic potassium salt in the eastern region of the Sichuan Basin is mostly seawater and deposited in a marine sedimentary environment. At the same time, the greenhouse effect caused by volcanic activity also provides climatic conditions for potassium salt deposition.