This paper presents the stable isotopic compo- sitions from the cave dripwater and actively forming soda straw stalactites collected from Wanxiang Cave, Wudu, Gansu, located on the Qinghai-Tibetan Plateau and Loess Pl...This paper presents the stable isotopic compo- sitions from the cave dripwater and actively forming soda straw stalactites collected from Wanxiang Cave, Wudu, Gansu, located on the Qinghai-Tibetan Plateau and Loess Plateau transition zone, China. The δ Odw and δ Ddw of 18 dripwater samples in the cave plot directly on the local MWL, constructed by using GNIP data from 3 sites surrounding the cave regions (Lanzhou, Xi’an, and Chengdu), the nearest site to the cave, suggesting that there is a close relationship be- tween the δ 18Odw of the cave water and the δ 18O of the pre- cipitations. Using the measured δ Odw and δ Omc values 18 18 from the mid-farthest parts from the cave entrance and the carbonate paleotemperature equation, the calculated tem- peratures range from 8.9 to 12.4℃, with the mean value of 10.7℃ and the temperature calculated at 8 locations in the farthest part of the cave is in the range of 10.1—12.4℃, with the mean value of 11.5℃, being consistent with the survey value(10.99℃)in the cave, slightly lower than the mean an- nual temperature (14.4℃) in Wudu. This suggests that mod- ern speleothems are forming under isotopic equilibrium and their isotopic composition accurately reflects the mean an- nual temperature at the surface, indicating that the isotopic composition of the modern speleothems records local tem- perature change with credibility.展开更多
文摘This paper presents the stable isotopic compo- sitions from the cave dripwater and actively forming soda straw stalactites collected from Wanxiang Cave, Wudu, Gansu, located on the Qinghai-Tibetan Plateau and Loess Plateau transition zone, China. The δ Odw and δ Ddw of 18 dripwater samples in the cave plot directly on the local MWL, constructed by using GNIP data from 3 sites surrounding the cave regions (Lanzhou, Xi’an, and Chengdu), the nearest site to the cave, suggesting that there is a close relationship be- tween the δ 18Odw of the cave water and the δ 18O of the pre- cipitations. Using the measured δ Odw and δ Omc values 18 18 from the mid-farthest parts from the cave entrance and the carbonate paleotemperature equation, the calculated tem- peratures range from 8.9 to 12.4℃, with the mean value of 10.7℃ and the temperature calculated at 8 locations in the farthest part of the cave is in the range of 10.1—12.4℃, with the mean value of 11.5℃, being consistent with the survey value(10.99℃)in the cave, slightly lower than the mean an- nual temperature (14.4℃) in Wudu. This suggests that mod- ern speleothems are forming under isotopic equilibrium and their isotopic composition accurately reflects the mean an- nual temperature at the surface, indicating that the isotopic composition of the modern speleothems records local tem- perature change with credibility.
