藏东昌都盆地晚中生代地层物源属性特征与沉积环境演化:对区域成盐古流体迁移过程的指示  

The characteristics of provenance properties and sedimentary environment evolution of Late Mesozoic strata in the Qamdo basin of eastern Tibet:Implications for the migration process of regional salt-forming paleofluids

作　　者：李长忠 苗卫良[1,2] 张西营 朱登贤[4] 顾焕恩 马晓晨 LI ChangZhong;MIAO WeiLiang;ZHANG XiYing;ZHU DengXian;GU HuanEn;MA XiaoChen(Key Laboratory of Green and High-end Utilization of Salt Lake Resources,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining 810008,China;Key Laboratory of Salt Lake Geology and Environment of Qinghai Province,Xining 810008,China;University of Chinese Academy of Sciences,Beijing 100049,China;QingHai Salt Lake Industry Group Company Limited,Golmud 816000,China)

机构地区：[1]中国科学院青海盐湖研究所,盐湖资源绿色高值利用重点实验室,西宁810008 [2]青海省盐湖地质与环境重点实验室,西宁810008 [3]中国科学院大学,北京100049 [4]青海盐湖工业股份有限公司,格尔木816000

出　　处：《岩石学报》2025年第3期1043-1066,共24页Acta Petrologica Sinica

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0805);2020年度中科院西部之光青年学者项目(苗卫良);中国科学院青海盐湖所基础研究青年创新交叉团队项目(ISLJCTD-2022-2)联合资助.

摘　　要：藏东昌都地区与兰坪-思茅-呵叻成盐带空间位置毗邻,且盆内同样发育有丰富的中生代膏盐类沉积及大量盐泉,但二者间在物源演化关系和区域成盐古流体迁移过程等方面研究薄弱且存在争议。本文以昌都盆地为主要研究区,通过对盆地内3个中生代长序列地层剖面沉积学、岩相学、矿物学研究,结合沉积物硅酸盐相元素地球化学特征分析,探讨了研究区的物源属性特征、沉积环境演化及区域内的古流体迁移过程,并尝试揭示昌都地区与兰坪-思茅-呵叻成盐带之间的物源关系。研究结果表明,昌都盆地中生代沉积地层兼具被动大陆边缘、活动大陆边缘及大陆岛弧等物源区大地构造背景信息,显示了研究区长期以来的混合物质来源。昌都盆地晚中生代地层的源岩属性特征均以长英质酸性岩系为主,且与兰坪-思茅盆地对应地层的物源属性特征具有较高的相似度。昌都盆地的沉积环境从中侏罗世的海陆过渡相环境逐渐演变为晚侏罗世-晚白垩世的内陆河流-湖泊相环境。结合砂岩粒度特征及概率累计曲线分析,发现中侏罗世以来盆地内的沉积环境由浅湖-半深湖相环境逐渐演变为滨浅湖相环境、河流-湖泊三角洲相环境。通过对昌都盆地与兰坪-思茅-呵叻成盐带之间物源演化关系的讨论,认为晚中生代昌都盆地陆相古湖盆圈闭了大规模的变质海水,为兰坪-思茅-呵叻成盐带巨型“异常”蒸发盐的形成提供了物质基础。The Qamdo area in eastern Tibet is geographically adjacent to the Lanping-Simao-Khorat salt-forming belt.In addition,abundant gypsum deposits from the Mesozoic era and many salt springs developed in the basin.However,the weak research level on both aspects has led to much controversy regarding the evolution relationship between material sources and the migration process of ancient salt fluids in the region.In this paper,the main research area is the Qamdo basin.Through the study of sedimentology,lithology,and mineralogy of three Mesozoic long-section stratigraphic profiles within the basin,combined with the geochemical characteristics of silicate facies elements,the provenance characteristics,the evolution of the depositional environment and paleofluid migration process is discussed in the study area.And attempt to reveal the provenance relationship between the Qamdo area and the Lanping-Simao-Khorat salt-forming belt.The results showed that Mesozoic sedimentary strata in the Qamdo basin encompass the tectonic background information passive continental margin,active continental margin,and continental island arc,which shows a long-term mixed provenance of materials sources in the study area.The parent rock property characteristics of the Late Mesozoic strata in the Qamdo basin are predominantly by quartz-feldspathic acidic rock series,and they exhibit a high degree of similarity to the provenance attributes of the corresponding strata in the Lanping-Simao basin.The Qamdo basin has seen its sedimentary environment gradually evolve from a paralic transitional facies phase in the Middle Jurassic to an inland river-lake facies sedimentary environment during the Late Jurassic to Late Cretaceous periods.Combining the grain size characteristics of sandstone and the analysis of cumulative probability distribution curves,since the Middle Jurassic,the shallow lake to semi-deep lake facies environment has gradually evolved from a shore shallow lake facies environment to a river-lake delta facies environment in the basin.Thro

关 键 词：昌都盆地 物源属性 沉积环境演化 古流体迁移 

分 类 号：P512.2[天文地球—地质学] P542