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  

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

作　　者：丁婷 袁苗 刘成林[3,4] 赵艳军[4] 朱志军[1] 杨庆坤[1,5] DING Ting;YUAN Miao;LIU Cheng-lin;ZHAO Yan-jun;ZHU Zhi-jun;YANG Qing-kun(East China university of Technology,Nanchang 330013,China;Urumqi Comprehensive Survey Center on Natural Resources,China Geological Survey,Urumqi 830057,China;China University of Geosciences,Wuhan 430074,China;MLR Key Labora tory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Tourism,Qinghai Minzu University,Xining 810007,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌昌330013 [2]中国地质调查局乌鲁木齐自然资源综合调查中心,新疆乌鲁木齐830057 [3]中国地质大学(武汉),湖北武汉430074 [4]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [5]青海民族大学旅游学院,青海西宁810007

出　　处：《岩石矿物学杂志》2023年第6期868-877,共10页Acta Petrologica et Mineralogica

基　　金：国家重点研发计划(2026YFC2906603);国家自然科学基金项目(41902065,42362018);第三次新疆综合科学考察项目课题(2022xjkk1303);新疆重大科技专项(2022A03009-4)。

摘　　要：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0.707895,硬石膏岩的87Sr/86Sr值平均为0.708174,石盐岩的87Sr/86Sr值平均为0.708177,同时碳酸盐岩的87Sr/86Sr值从早三叠世的0.707413快速增加到中三叠世早期的0.708515,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,同时由于火山作用造成的温室效应也为钾盐沉积提供了气候条件。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~(87)Sr/~(86)Sr value of carbonate rocks is 0.707895,the average~(87)Sr/~(86)Sr value of anhydrite rocks is 0.708174,and the average~(87)Sr/~(86)Sr value of halite rocks is 0.708177,and the~(87)Sr/~(86)Sr value of carbonate rocks increased rapidly from 0.707413 in the Early Triassic to 0.708515 in the early Middle Triassic,and then showed a downward trend.Overall,the~(87)Sr/~(86)Sr values are close to the published global~(87)Sr/~(86)Sr 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.

关 键 词：锶同位素 蒸发岩 古环境重建 早中三叠世 四川盆地东部地区 

分 类 号：P588.24[天文地球—岩石学] P597[天文地球—地质学]