摘要
土林是在干旱-半干旱地区典型的流水侵蚀地貌,研究其物质组成可揭示土林沉积环境演变过程,为进一步探究土林的发育演化奠定基础。本文采用粒度分析方法,对其地层剖面沉积物组成特征进行了研究。结果表明:(1)大同土林沉积物的粒度组成以粉沙为主,平均含量高达50.6%,其次为黏土,平均含量为36.01%,粗颗粒组分的含量较低。(2)自然频率分布曲线呈单峰和双峰分布模式,相应的累积频率曲线也呈单一直线型和两段型分布模式,表明土林沉积物组成以悬移组分占主导。(3)随着土层深度的增加,土林沉积物平均粒径呈波动变粗的趋势,分选性由较差向差波动变化,偏度由负偏经近对称向正偏转变,峰态多为宽和中等。大同土林沉积物主要形成于河流相和湖泊相沉积的环境,并夹有风成地层,且这些地层在垂直剖面上呈互层分布。土林的形成受内、外营力的共同影响,其发育演化过程与当地气候变化密切相关。
Earth forests are typical fluvial erosion landforms,which refer to a series of positive and negative relieves,such as column-shaped and wall-shaped forests,as well as gullies.The materials that composed the earth forests are previously deposited semi-loose to semi-consolidated fluvial and lacustrine strata.Therefore,the earth forests.strata bear abundant information on regional environmental change.By applying grain size analysis to the sediments of earth forests.strata,this study tentatively demonstrates the material composition and the regional sedimentary environment.s variation processes.A study on grain size characteristics of earth forest landform sediments in the Datong Basin can make clear its material composition and sedimentary environment and provide a scientific basis for the development and evolutionary history of earth forest landforms.Here,23 sediment samples were collected from a stratum profile of earth forest,and their grain size grading,frequency distribution curves,and grain size parameters were analyzed.The results indicated that the earth forest in the Datong Basin was mainly composed of silt,with an average content of 50.6%,followed by clay,with an average content of 36.01%,and the contents of coarser grain size fractions were scarce.The frequency distribution curve showed uniand bi-modal distribution patterns.The cumulative grain size frequency curves showed one-and two-segment distribution patterns,which indicated suspension and saltation loads,and each component’s content varied.With the increase in soil depth,the average particle size tends to fluctuate and become coarser.The sorting characteristics fluctuate from moderately poor to poor.The skewness changed from nearly symmetrical to negative and eventually positive.The kurtosis was mostly wide and medium.Sediments of the Datong earth forest were mainly formed in the aeolian,fluvial,and lacustrine sedimentary environments,and these strata were vertically interbedded.The formation of the earth forest is affected by internal and external forces,and its developmental and evolutionary process is closely related to the local climate change.The earth forests’strata are usually deposited in the fluvial and lacustrine environments during relatively warmer conditions,while they are deposited by aeolian deposition during the arid climate.
作者
蔡莹莹
李继彦
屈欣
王萌
王颖颖
CAI Yingying;LI Jiyan;QU Xin;WANG Meng;WANG Yingying(School of Geography Science,Taiyuan Normal University,Jinzhong 030619,Shanxi,China)
出处
《干旱区研究》
CSCD
北大核心
2021年第3期892-900,共9页
Arid Zone Research
基金
山西省高等学校科技创新项目(2019L0797)。
关键词
土林
粒度
沉积环境
大同盆地
earth forest
grain-size
sedimentary environment
Datong Basin
