Contemporary karst solution processes on the Tibetan Plateau

Abstract

The Tibetan Plateau, with an average elevation of 4,000-5,000 m a.s.l., is cold and arid, and geomorphologic processes are dominated by periglacial, glacial, and aeolian agents. Here, the highest known, currently-developing karst features were found during the Sino-British Expedition of 1987. Measurements of CO2 partial pressure were taken in air, soil, sediments, and caves. Also measured were the solubility of Tibetan limestones, the dissolved CaCO3 in water, and the electrical conductivity of karst waters. Field solution experiments show that CO2 partial pressure is one of the lowest in the world. Dissolved limestone content in fresh karst water is lower than in other karst areas. The solubility of the major Tibetan limestones varies little, but field experiments indicate that karst solution rates are affected by geomorphologic and climatic conditions. The formation and distribution of the present-day karst features correspond with the results of field and laboratory solution experiments. They are mainly small surface features in relatively wet and warm locations, especially where soil is in direct contact with limestone. Measurements of solution rates and CO2 content indicate that biologically stimulated solution plays an important role in karst development on this cold and arid plateau.