A comparative study on the stable isotopes from precipitation to speleothem in four caves of Guizhou, China

Monitoring and sampling of soil waters, and cave drip waters were performed monthly at four caves of Guizhou, Southwest China, from April 2003 to May 2004, in order to comparatively study the control factors of stable isotope in drip waters and their corresponding speleothems. δD and δ18O were measured for all samples including precipitation, soil waters, drip waters and modern speleothems. These results indicate that the amplitudes of the isotope values decrease gradually from precipitation to drip water in these caves, obviously suggesting the homogenization. Under certain conditions, it is possible to use speleothems to study high resolution (seasonal, even monthly) paleoclimatic changes in Liangfeng Cave (LFC) and Qixing Cave (QXC), but only low resolutions (more than a year) could be reached in Jiangjun Cave (JJC) and Xiniu Cave (XNC). The relationships between local meteoric water line (LMWL) and isotopic data of fluid inclusions in speleothems from the four caves can estimate local paleoclimate and paleoenvironment; however, it is debatable whether d-excess values can predict them. The effects of hydrological processes on the δ18O values in drip waters cannot be ignored. Hydrochemistry may cause isotopic disequilibrium in the formation of speleothems.