The Shuilian Cave in the Upper Region of the Chang River (Karst of NW Yunnan, China)

In upper reaches of the Chang (Yangtze) river, in Deqen prefecture, in northwestern part of the Yunnan province, karst is developed in Devonian carbonate rocks. The Shuilian cave, more than a kilometre long, formed along the contact of fine bedded metamorphosed calcitized sandy siltstones and calcitized siltstones. The cave has two entrances, the upper one being dry and the lower entrance with a steady water flow. It is situated in the steep slope about 70 m above the river level (1,965 m a.s.l.). In the paper a detailed analysis of rocks that host the cave is presented, and also a comprehensive description of the rock morphology and shapes of the cave conduits. Physico-chemical properties of water from cave and from a nearby spring were measured. The temperature and specific electric conductivity determinations indicate a relatively long underground residence time of water which, however, relatively poorly dissolve slowly dissoluble base rock. This could be the explanation for stagnation of the karst deepening with respect to erosional downcutting of the river Chang. In addition, further research is proposed.