Indication capability for karst development elevation by knickpoints in Daba Mountain (Southwest China)

Abstract

Regional tectonic uplift information is recorded by knickpoints distributed in multiple rivers. The changing base level (mainstream) caused by tectonic uplift also controls karst development. Groundwater should drain as springs near the base level due to karstification usually occurring near the base level, but some drains were higher than the present river in the canyon. The assumption is proposed that the spring is more elevated than the current river formed at the older intermittent stage in uplift processes and that knickpoints at the elevation can correspond to the springs. A typical basin south of Daba Mountain is selected to identify the assumption. Three knickpoints with 11 karst landforms suggest that knickpoints can indicate the karst development elevation in the basin. This method is promoted to 29 basins around Daba Mountain which are separated into DTB (North Daba Mountain Pre-Land Thrust Fault Belt) representing north part and DFB (South Daba Mountain Pre-Land Fold Belt) representing south part to verify the effectiveness of the assumption. The result discovers that the knickpoints and karst landforms have a similar high-frequency elevation interval in DFB and little variance in DTB. The reason may be that DFB has better karstification conditions, including precipitation and carbonate rock cover area, than DTB. Knickpoints is an effective indicator for karst development in area that has sufficient karstification condition like DFB. This study may provide a new perspective on the relationship between karst development and tectonic uplift and a method to find the karst groundwater drain elevation.