巴丹吉林大沙山地区盐膜微地貌与形成机制  

Salt-film microtopography and its origin in the megadune area of the Badain Jaran Desert

作　　者：赵景波 马延东 邵天杰 陈宝群[1] Jingbo Zhao;Yandong Ma;Tianjie Shao;Baoqun Chen(School of Geography and Tourism,Shaanxi Normal University,Xi’an 710062,China;Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region,Ministry of Education,Chang’an University,Xi’an 710054,China;Key Laboratory of State Forestry Administration on Soil and Water Conservation&Ecological Restoration of Loess Plateau,Shaanxi Academy of Forestry,Xi’an 710082,China;Planetary Aeolian Research Institute,Shaanxi Normal University,Xi’an 710119,China)

机构地区：[1]陕西师范大学地理科学与旅游学院,西安710062 [2]长安大学旱区地下水文与生态效应教育部重点实验室,西安710054 [3]陕西省林业科学院黄土高原水土保持与生态修复国家林草局重点实验室,西安710082 [4]陕西师范大学行星风沙科学研究院,西安710119

出　　处：《科学通报》2024年第17期2441-2453,共13页Chinese Science Bulletin

基　　金：国家自然科学基金(41901034,41930641);《中国沙漠志》编纂技术服务协议项目(ZGSM-01)资助。

摘　　要：通过野外调查和实验分析,在巴丹吉林沙漠沙山地区发现了盐膜弧形球粒台阶微地貌、直线形盐膜悬空台阶微地貌、盐膜蝌蚪形微地貌和盐膜针形微地貌等多种类型的独特微地貌.这些盐膜微地貌大多是过去没有认识到的微地貌新类型,对它们进行研究具有发展微地貌学和揭示该区水循环及水分平衡的重要意义.该区盐膜微地貌形成动力可分为4种,分别是大气降水在包气带细粒层中富集形成的地下弱径流、地下弱径流出露地表形成地表弱径流、强烈蒸发引起的水分运移和后期的风动力.该区存在的有效大气降水在粗粒层和细粒层中的差异分布是盐膜微地貌形成的关键条件,盐类的胶结是微地貌形成的直接因素.盐膜微地貌和弱径流分布表明,沙山地区沙层水分为正平衡,在降水经过蒸发与蒸腾损失之后,仍有剩余水分补给地下水和湖水.盐膜微地貌形成机制是:有效大气降水→入渗水的差异分配→粗粒贫水层与细粒富水层出现→地下弱径流产生→地表弱径流形成→地表弱径流被强烈蒸发→盐类沉淀与盐类胶结沙层→盐膜形成→细粒层变坚硬→风力侵蚀→粗粒层凹进→细粒层凸出→盐膜阶梯等微地貌形成.盐膜化学成分的能谱分析发现,在极端干旱气候条件下Nb2O3和TiO2明显富集,这两种成分的明显富集可作为指示极端干旱气候环境的新指标.这项研究将拓展人们对干旱区沙丘地貌和水循环的认知.The origin of the numerous lakes in the Badain Jaran Desert region has attracted much research attention,and in particular the source of the lake water is strongly debated.Numerous previous studies of the water source of these lakes have been conducted using techniques such as analyses of the stable isotope composition of lake water and the moisture content of sand layers.However no research has been conducted on the salt film present on the various microtopographies of this region,which can indicate the occurrence of sub-surface microrunoff and the water cycle of the megadunes.Based on field investigations and laboratory analyses we characterized the salt films on the unique microtopographies of the megadune areas,including salt film arc-shaped spherical terrace microtopography,linear salt film on overhanging terrace microtopography,salt-film“tadpole”microtopography,and salt-film needle microtopography.Most of these salt-film microtopographies were not previously recognized and understanding their origin is geomorphologically significant as well as important for understanding the water cycle of the megadunes.The formation of salt-film microtopographies in this region can be classified into four types:Weak underground runoff formed by the accumulation of atmospheric precipitation within the fine-grained layer of the vadose zone;weak surface runoff formed by the diversion to the surface of weak underground runoff;water transport caused by strong evaporation;and wind dynamics in a later stage.The occurrence of effective precipitation and the differential distribution of precipitation between coarse-and fine-grained layers are the key conditions for the formation of salt-film microtopography,and the cementation of salts is also a direct factor in its formation.The salt-film microtopography and weak runoff in this area indicate that the sand layers have a positive water balance,with residual water being available to recharge the groundwater and lake water after losses by evaporation and transpiration.The fine-gra

关 键 词：盐膜微地貌 微径流 新生盐 水循环 巴丹吉林沙漠 

分 类 号：P931.3[天文地球—自然地理学]