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 globeil 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 Eire 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. [ABSTRACT FROM AUTHOR]