Evaporite karst and resultant geohazards in China

Abstract

The main kinds of evaporite karst, both sulphate karst and halide karst, are widely distributed in China. Gypsum karst is especially widespread, because China contains the largest gypsum resources in the world. These gypsum deposits range in age from Precambrian to Quaternary, and they were deposited in many environments, including marine, lacustrine, thermal process, metamorphic, and also as secondary deposits. Halide karst is developed in rock salt and salt-water lakes, the latter related to more than 300 salt-water lakes distributed in the Qinghai Plateau of Xizang (Tibet) province. Gypsum and halite are easily dissolved; therefore, development of evaporite karst is somewhat different when compared with carbonate karst, which has developed many typical features in China. This paper discusses the mechanism and development of evaporite karst in sulphate rocks and in halides, and makes comparisons between evaporite karst and carbonate karst based upon field investigations and new tests in the laboratory. The geohazards of evaporite karst usually are triggered by natural karst processes, but often they are exaggerated by artificial (human) actions and engineering impacts that cause flesh groundwater or surface water to come in contact with the evaporite rocks. Some examples of evaporite-karst geohazards are described in this paper; they are present in Shandong, Sichuan, and Guizhou Provinces, and in the Qinghai Plateau of China.