Geochemical analysis of yardang strata in the Dunhuang Yardang National Geopark, Northwest China, and implications on its palaeoenvironment, provenance, and potential dynamics
Geochemical analysis of yardang strata in the Dunhuang Yardang National Geopark, Northwest China, and implications on its palaeoenvironment, provenance, and potential dynamics
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敦煌雅丹国家地质公园雅丹地层地球化学分析及其古环境、物源和潜在动力学意义
DOI：
10.1016/j.aeolia.2019.06.003
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发表时间：
2019-10-01
期刊：
影响因子：
3.3
通讯作者：
Liu, Taotao
中科院分区：
文献类型：
--
作者：
Liang, Xiaolei;Niu, Qinghe;Liu, Taotao
雅当斯是由神秘的过程形成的地貌。雅当地层的沉积相特征反映了它们对风蚀的脆弱性，这对了解它们的形态发育具有重要意义。然而，由于缺乏对这些地质构造的物源和导致其形成的沉积环境的系统研究，限制了雅当沉积模式的概念。本研究应用地球化学分析方法对敦煌雅当国家地质公园的雅当沉积物进行了研究，以化学元素的分异和聚集为基础，通过惯例来表征物源和沉积环境。结果表明，北山、阿尔金-塔格、罗布泊、疏勒河都是敦煌雅当发展的重要物质来源，其中北山和阿尔金-塔格占主导地位。根据地貌形态，雅当的运移和沉积过程可分为三种不同的类型：北山和阿尔金-塔格的冲积洪水，罗布泊和疏勒河的直接沉积(如河湖消退所示)和风化作用后河湖相的泥沙再运移。根据我们的研究结果，敦煌雅当油田的沉积环境由河流、湖泊、冲积和风成地层组成。就沉积演化而言，敦煌雅当油田具有风成和水成两种周期性沉积的特点，其剖面的古地貌形态也表现出明显的差异。我们的发现对了解雅当地貌的形成和发展具有理论意义，对保护这些地质遗迹具有实际意义。
Yardangs are landforms created by enigmatic processes. Sedimentary facies characteristic of yardang strata illustrate their vulnerability to wind erosion, which is important for understanding their morphological development. However, the lack of systematic research on the provenance of these geological structures and the sedimentary environment that led to their development have limited the conception of a yardang sedimentary model. In this study, we apply geochemical analysis to investigate yardang sediments from the Dunhuang Yardang National Geopark to characterize the provenance and the sedimentary environment through conventions based on the differentiation and aggregation of chemical elements. Results show that Beishan Mountain, Altyn-Tagh, Lop Nur, and the Shule River are all key material sources for the development of Dunhuang yardang, of which the Beishan Mountains and Altyn-Tagh predominate. As determined by geomorphological patterns, yardang transportation and sedimentary processes can be divided into three distinct types: alluvial flooding from Beishan Mountain and Altyn-Tagh, direct deposition from Lop Nur and the Shule River (as illustrated in river lake fades), and sediment re-transportation during river-lake phases following weathering processes. According to our results, the sedimentary environment of the Dunhuang yardang field is composed of fluvial, lacustrine, alluvial, and aeolian strata. With regards to its sedimentary evolution, the Dunhuang yardang field is characterized by periodic deposition both aeolian and aqueous sediments, and the profiles exhibit obvious differences respective to their paleogeomorphic patterns. Our findings are theoretically significant for understanding the formation and development of yardang landforms and practically significant for protecting these geological relics.