敦煌雅丹地层易溶盐特征及其对沉积环境的指示意义
Soluble salt deposition of the Dunhuang yardang strata and its indication for sedimentary environment
梁晓磊 1程志花 2翟晓慧 1牛清河 3张益明 4李艳丽4
作者信息
- 1. 太原师范学院经济与管理学院,山西晋中 030619
- 2. 太原师范学院地理科学学院,山西晋中 030619
- 3. 中国科学院西北生态环境资源研究院敦煌戈壁荒漠研究站/甘肃省风沙灾害防治工程技术研究中心/沙漠与沙漠化重点实验室,甘肃兰州 730000
- 4. 敦煌市雅丹景区服务中心,甘肃敦煌 736200
- 折叠
摘要
雅丹地层是雅丹地貌形成发育的物质基础,记录了沉积过程、环境演化、地貌格局等大量的地表过程信息,而沉积物理化分析则成为解读其关键信息的重要前提.易溶盐特征作为重要的环境代用指标对解读雅丹地层沉积演化过程具有重要指示意义.以敦煌雅丹地貌为研究对象,对其出露地层的易溶盐沉积特征、环境代用指标以及沉积环境演化等进行了深入探讨.结果表明:(1)敦煌雅丹地层沉积物优势离子以Mg2+-Na+-Ca2+-Cl--SO42-组合为特征,相应的离子类型主要包括Cl-Na型与SO4-Ca-Mg;(2)主要离子与总含盐量纵向旋回变化特征显著,以硫酸盐和氯化物盐交替演化为主,二者对雅丹易溶盐沉积具有决定性控制作用;(3)环境代用指标Mg2+/Ca2+、Cl-/SO42-等在雅丹环境变化研究中具有一定的局限性,表明雅丹地层并非完全由稳定的湖泊沉积发育而来;(4)雅丹地层是不同沉积环境和动力机制下形成的多种物质交替沉积的结果,主要包括静水湖泊、湖滨、河流、风成和冲积扇远端泥坪物质,其中湖滨、河流与风成沉积物的理化性质相近,难以有效区分,有待进一步深入研究.
Abstract
The yardang strata is the material manifestation of the sedimentary system before the yardang land-form developed.It records a large amount of surface process information such as sedimentation processes,envi-ronmental evolution,and landform patterns.The physical and chemical analysis of sediments has become an im-portant prerequisite for interpreting its key information.As an important environmental proxy index,the charac-teristics of easily soluble salts have important significance in interpreting the sedimentary evolution process of the yardang Formation.This paper takes Dunhuang yardang landforms as the research object,and conducts an in-depth discussion on the soluble salt deposition characteristic,environmental proxy indicators and sedimentary en-vironment evolution of its exposed strata.The results indicated that:(1)The dominant ions'composition of solu-ble salts in yardang sediments is characterized by the combination of Mg2+-Na+-Ca2+-Cl--SO4-,and the corre-sponding ion types mainly include Cl-Na type and SO4-Ca-Mg type.(2)The main ions and the total salt content in the studied profiles have significant vertical cycle variation characteristics,mainly dominated by the alternat-ing changes of sulfate and chloride salts,both of which play a decisive role in controlling the deposition of yard-ang soluble salts.(3)Environmental proxies such as Mg2+/Ca2+and Cl-/SO42-have certain limitations in the differ-entiating of yardang environmental changes,indicating that yardang strata were not entirely developed from sta-ble lacustrine deposition.(4)The yardang formation is the result of alternate deposition of various materials formed under different sedimentary environments and dynamic mechanisms,which mainly includes stable lacus-trine,lakefront,fluvial,aeolian and alluvial fan's mud flat materials.Among them,lakefront,fluvial and aeoli-an sediments have similar physical and chemical properties,making it difficult to distinguish in detail and need further study.
关键词
雅丹地层/沉积物/易溶盐/主要离子/沉积环境Key words
yardang strata/sediment/soluble salt/dominant ions/sedimentary environment引用本文复制引用
基金项目
国家自然科学基金青年科学基金(42001007)
国家自然科学基金面上项目(42171016)
出版年
2024
NETL
NSTL
万方数据