元谋干热河谷强侵蚀区陷穴发育特征与演化过程

元谋干热河谷潜蚀地貌发育，是造成当地水土流失的重要原因之一。而陷穴属于潜蚀地貌的一种，因此有必要了解陷穴特征及演化过程。2009―2013年，通过多次现场测定陷穴形态特征、陷穴发育地地形地貌、周边植被特征等，并对土壤进行取样分析。结果表明：1）元谋陷穴主要发育于元谋组地层，土壤具有易崩解性、湿陷性等特征；2）陷穴主要分布于冲沟中上游沟底及支冲沟沟头部位；3）元谋陷穴形态规模总体不大，早期多呈近圆形，中晚期多为椭圆形，直至消失后成为沟中之沟；4）陷穴一般呈单个和串珠状分布，较少出现集群现象；5）演化过程遵循一般事物的发展规律，分为萌芽期、年轻期、成熟期、消亡期４个阶段；6）陷穴发育过程与冲沟、土桥、淘洞等地貌密切相关。

Development Characteristics and Evolution Process of the Sink Holes in Yuanmou Dry-Hot Valley

Yuanmou dry-hot valley is located in Jinsha River Basin in the upper reaches of the Yangtze River. It is a typical subtropical climate area with special geographical position and geologic environment. The development of erosional landforms is one of the main reasons for water and soil loss in Yuanmou dry-hot valley. Sink hole is a type of erosional landforms. From 2009 to 2013, field survey was made on the morphological features of the sink holes, the topography and geomorphology of their surrounding areas, and the vegetation and soil around the sink holes. Also the soil of the areas was sampling and analyzed. The results show that the sink holes mainly develop in the strata of Yuanmou formation, where the soil is characterized by its easy disintegration and collapsibility. The sink holes are located at the bottom in the middle and upper reaches of gully and at the top of gully branches. The shape and scale of the sink holes in Yuanmou are generally small. In early stage they are approximately circular in shape, in middle and late stages they are elliptic, and in last stage they become gullies within gully, and even disappear. The sink holes are normally distributed individually, or like a string of beads, but rarely clump together. The evolution process of the sink hole can be divided into four stages, namely germination stage, young stage, mature stage and withered stage. There is close correlationship between the developing process of sink hole and the erosional landforms such as gully, earth bridge and washing hole, etc.