Field examination of limestone dissolution rates and the formation of active karren on the Tibetan Plateau

Abstract

Karst dissolution rates on the Tibetan Plateau were measured by using standard limestone tablets that lay in air, soil, sediment and on the limestone surface for more than 10 years. In most cases the tablets from the limestone surface and air show little sign of dissolutional processes, because of the prevailing highly arid conditions and low content of CO2 in the air. Such low rates of dissolutional activity probably indicate that most types of karren found on the plateau are not active karst features. The samples in sedimentary detritus generally gained weight, indicating that deposition is taking place. This reflects both the overall aridity and the strong evaporation related to intense solar radiation input and the small amount of precipitation. Dissolution occurs only in the soil layer, which has a higher CO2 content, indicating that biogenic karst processes are the major producer of currently active karst features in this cold and arid highland.