Transmission of oxygen isotope signals of precipitation-soil water-drip water and its implications in Liangfeng Cave of Guizhou, China

Abstract

According to systemically monitoring results of oxygen (hydrogen) isotope compositions of precipitation, soil waters, soil CO2, cave drip waters and their corresponding speleothems in Liangfeng Cave (LFC) in Guizhou Province, Southwest China, it is found that local precipitation is the main source of soil waters and drip waters, and that the amplitudes of those δ 18O values of three waters (precipitation, soil water and drip water) decrease in turn in the observed year, which are 0% to −10%, −2% to −9% and −6% to −8%, respectively. Moreover, the δ 18O values for three waters show a roughly simultaneous variation, namely, that those values are lighter in the rainy seasons, weightier in the dry seasons, and that the average δ 18O value of drip waters is about 0.3% weightier than that of precipitation, which is modified by surface evaporation processes. We also find that soxygen isotope equilibrium is reached or neared in the formation processes of speleothems in LFC system, and that it is feasible to reconstruct paleotemperature and paleoprecipitation by using δ 18O values of speleothems. However, it should be noted that surface evaporation would affect the oxygen isotope values in the study area.