锥峰和塔峰溶丘地貌的表层喀斯特带径流溶蚀形成机制

Dynamic Mechanism of Runoff Corrosion in the Epikarst Zone on the Formation of Cone and Tower Karst Landforms

塔峰、锥峰和常态山是西南喀斯特地区的三种主要丘陵形态。表层喀斯特带径流溶蚀动力学机制可以较好的解释喀斯特坡地发育。表层喀斯特带的顺坡径流量大的喀斯特地区,坡地溶蚀速率高,易于塔峰和锥峰地貌的形成,反之,易于常态山地貌的形成。降水、岩层组构等环境要素控制了表层喀斯特带的顺坡径流量。西南喀斯特地区的这三种溶丘的空间分布和这些环境要素的区域差异有关。滇东高原、贵州高原和广西丘陵平原的岩性和大地构造条件差异不大,气候是这三地溶丘地貌形态差异的主要原因:滇东高原为西南季风气候区,降水量较低,表层喀斯特带顺坡径流量小,溶丘地貌以常态山为主;其余两地为东亚季风气候区,降水量较高,表层喀斯特带顺坡径流量大,溶丘地貌以锥峰和塔峰为主,其中,广西丘陵平原的降水量大于贵州高原,前者溶丘地貌以塔峰为主,后者以锥峰为主。

Tower,cone and normal karst hills are three major types of karst hills in the karst area of Southwest China.A dynamic mechanism of chemical erosion by the runoff in the epikarst zone,proposed in this paper,is able to explain slope evolution of karst hills.In the karst area,where the epikarst zone of a hill has big down slope runoff discharge,chemical erosion rate is high on the hill slope and it is prone to formation of tower and cone karst hills,otherwise prone to formation of normal karst hills.The relevant environmental factors,such as,precipitation and rock texture and structure have great influences on the down slope runoff discharge in the epikarst zone.Spatial distribution of the three types of karst hills are related to the variation of those environment factors in the karst area of Southwest China. The Eastern Yunnan Plateau,the Guizhou Plateau and the Guangxi Hilly Plain have no significant differences in lithology of carbonate rocks and geotectonics and climate is the principle factor for the difference in karst hill shapes between the three areas.In the Eastern Yunnan Plateau experiencing the Southwest Monsoon climate,the normal hill is the principle karst hill type,because of the relatively low precipitation.In the other two areas,the cone and tower hills are the principle karst hill types because of the high precipitation,in which the tower is the principle shape in the Guangxi Hilly Plain area with the highest precipitation while the cone is the principle type in the Guizhou Plateau with the relatively higher precipitation.