巴江流域演变与路南石林发育耦合分析

本文分析了巴江喀斯特流域的水系、地貌结构特征，通过多次野外调研，探讨了石林的形态及其在巴江流域内的空间分布特征。研究表明石林主要发育在二叠系的栖霞组、茅口组灰岩上，岩性和地层的差异对石林的形状有较大影响；石林的分布在地貌部位上并无明显的选择性，在洼地、斜坡及山顶均可发育，但石林的形态和高度在三种地貌部位间有明显的变化规律；以路南群为中心，往北、东方向距路南群越远，石林的高度有逐渐减小的趋势，同时石柱间的距离也越来越大，由簇状石林向分离程度很好的单个石柱变化；天生桥为一地貌裂点，石林的形态和分布特征在其上、下也表现出明显的差异。同时，根据石林发育的“三元剥蚀”机制，结合路南地区的水文、地质、地貌演化史，作者进一步分析了路南石林发育和巴江流域演变之间的内在联系，并把路南石林的发育划分为三个时期，即路南古湖期、石林遍生期和流域回春期。作者认为，石林的出现和大范围分布并非偶然，而是巴江流域演变到一定阶段的产物。

A Coupling Analysis on the Evolution of Bajiang River’s Catchment and the Development of Lunan Stone Forest

As a kind of rarely-seen landform, the origin and evolution of stone forest receive wide-spread attention from international karstic research community. In China, the most typical and famous stone forest is the one called Lunan Stone Forest located in the east of the Yunnan Plateau, Southwestern China. It is believed that the development of the Lunan Stone Forest is closely related to the evlolution of the Bajiang River Catchment, where the stone forest lies. The authors have studied the structural characteristics of river system and geomorphology of Bajiang River, and the geographical feature of stone forest in the catchment and also its morphological features. It reveals that the stone forest, deeply influenced by the local lithology and stratum, mainly occurs in Permian Qixia and Maokou Formation; the spatial distribution of stone forest appears independent from landforms, and it is found in depressions, on the slope of as well as at the top of hills; however, the shape and tallness of stone pillars obviously change among the three kinds of landforms; the farther away from the Lunan Group, the shorter the stone pillars , and the bigger the distance among the pillars, from cluster-shaped to single pillar; the Tianshengqiao Natural Bridge is actually a knickpoint for Bajing River, where exists a great difference in stone forest’s morphology and geographic feature between its upper and lower reaches. At the same time, according to the “triple erosion” mechanism of stone forest development, and based on the evolution history of hydrology, geology and geomorphology in Lunan area, the authors make a further analysis on the internal connection between the catchment evolution of Bajiang River and the development of stone forest, and divide the history of stone forest into three stages, that is, the ancient Lunan Lake stage, the stone forest omnipresent stage, and the catchment rejuvenation stage. The authors argue that the origin and extension of stone forest is not accidental but an evolutional product of Bajiang River Catchment.