Distribution of soluble rock strata and development of karst landforms in the Batang area, west Sichuan plateau

This paper focuses on Batang county and Baiyu county， west Sichuan plateau. Based on data from field investigations， we analyze the geological background， topography， lithologic characteristics and distribution of carbonate rocks in exposed strata from Triassic to Cambrian， especially rock composition， structural characteristics and the distribution of karst development in the study area. The features of carbonate strata and law of karst development in the study area are systematically summarized. Results show that the soluble strata in the study area are distributed in a NW-SE direction， indicating an obvious control of regional geological structure. The karst landform development in the study area is consistent with that in the main areas of Tibetan plateau， belonging to the paleokarst formed by the exposed surface of the cover-type karst， which developed and evolved in a tropical-subtropical environment during Tertiary time with many karst types and distinct morphology and scales. Statistics of the karst development degrees of different carbonate rock formations shows that the Devonian depression occupies the largest area， and the Triassic and Silurian carbonate strata have more depressions， but their development density is lower than the Devonian. The number and area of Permian depressions are the smallest. The density of the Carboniferous karst depressions is the largest because of their relatively high purity and concentrating exposure.