摘要
由于红层岩性、节理发育状态、年代、构造运动特征、气候以及区域地质地理条件等的不同,丹霞地貌的形态在区域上有很大差别,其成因机制十分复杂.从丹霞地貌演化机制的宏观意义着眼,考虑岩性、节理、构造抬升速率及降雨等因素,基于地貌演化理论,利用数值模拟方法定量地展现了丹霞地貌坡地在构造抬升及流水侵蚀这两个主要的内外力作用下的动力学演化过程.地貌演化的幼年期和壮年期,流域输沙能力相对较大,主要表现为流水对基岩的侵蚀过程;直至演化的老年期,流域输沙能力相对较小,大量的风化物淤积,坡度变缓.同时,对不同岩性和垂直节理深度的计算结果进行了对比分析,砾石质地相对坚硬,计算得到的高程较大,表明岩性硬度越高,较容易形成陡壁,而岩性较软,易形成丘陵.垂直节理深度不同,坡地峰值几乎相同,但浅垂直节理较深垂直节理的谷值大,表明流水沿垂直节理进行下切侵蚀的程度不同,对景观的形成有着重要影响.数值模拟结果在物理上是合理的,有利于进一步定性地认识到岩层岩性、节理、构造抬升及流水侵蚀对丹霞地貌坡地演化的作用.
Due to the differences in rock character of the red beds,joints status,durations,tectonic features,climate and physiographic conditions,the diversifications of the Danxia landforms are different in different places in China.The geneses of the landform are very complicated.We mainly focused on the macro significance of Danxia landform genesis,and tried to use numerical simulation based on the geomorphic evolution theory to model Danxia hillslope evolution.The basin type,stratum,tectonic uplift rate and rainfall factors are main elements of controlling the landform development.Considering these factors mentioned above,the initial numerical results quantitative demonstrate dynamic evolution processes of Danxia hillslope between two main forces such as a internal force of the tectonic uplift and a external force of water erosion.In infancy to mature stage of the landform,the sediment transport capacity is relatively larger,fluvial incision of bedrock is the main evolution process.Until in old stage,the transport capacity is relatively smaller,much sediment deposits,and slope becomes low.We take comparison of the results between different rock characters and depths of vertical joints.The elevation of gravel is much larger than that of sand because of the texture of gravel is relatively rigid.The contrast analysis manifests that rock character is more rigid,the steep cliff forms easier,instead the hill forms easier.The elevation of peaks with different depth of the vertical joints are almost the same,but the elevation of valleys are much larger when the depths of vertical joint are smaller.These show that it is easier for water incision along vertical joints when the depth is much larger.These analysis manifest that numerical result is reasonable.By using numerical simulation,we further help the understanding of the Danxia landform genesis with the factors of rock characters,joints,tectonic structure,water erosion,and climate conditions.
出处
《地球物理学进展》
CSCD
北大核心
2012年第6期2429-2436,共8页
Progress in Geophysics
基金
国家重点基础研究发展计划项目(2009CB723906)资助
关键词
丹霞地貌
地貌演化
数值模拟
构造抬升
流水侵蚀
Danxia landform
Landform evolution
numerical simulation
tectonic uplift
water erosion
