中国岩溶2011，Vol.30Issue(1)：101-104,118,5.
神农架石笋氧同位素的海拔效应
Altitude effect on δ《'18》O in stalagmites from Mt.Shennongjia, central China
摘要
Abstract
Proxy dataδ18 O reflecting the oxygen isotope composition of meteoric precipitation are widely used in reconstructions of continental paleoclimate. Nevertheless, there has been a general debate that precipitation amount or temperature dominates the speleothem δ18 O signal. To assist interpretation of speloethem δ18 O time series, it is necessary to understand the impacts of main oxygen isotope fractionation during moisture transfer. Here we present the δ18 O records of stalagmites from three caves (Heilong, Qingtian and Sanbao caves) along a transect of progressively increasing altitudes (1 250～2 250m) in Shengnongjia (31.5～31. 7° N, 110. 2～110. 6°E), central China. We confirm the effect of altitude on stalagmite δ18 O that mean stalagmite δ18 O values from two different same time period decrease with increasing cave altitude at a rate of about -0. 1‰/100 meters, indicating that the oxygen isotope compositions of precipitation undergoes fractionation during the moisture transfer from low to high altitude. In fact, modern meteorologic precipitation data show that altitude effect has an effect on the δ18 O change at a rate of -0.2‰/100 meters, which exceeds more the speleothem result. Consequently, in addition to the isotopic influence of precipitation on stalagmite δ18 O, temperature differences between altitudes contribute greatly to δ18 O variation. In combining with annual averaging temperature in caves, an average d δ18 Op/dT of approximately -0. 25‰/℃ was calculated, which agrees with the result of isotopic equilibrium fractionation by O'Neil.关键词
岩溶洞穴/石笋/氧同位素/海拔效应/湖北神农架Key words
karst cave/ stalagmite/ δ18 O/ altitude effect/ Mt. Shennongjia, Hubei分类
天文与地球科学引用本文复制引用
段福才,孔兴功..神农架石笋氧同位素的海拔效应[J].中国岩溶,2011,30(1):101-104,118,5.基金项目
国家自然科学基金项目"神农架洞穴石笋氧同位索对山地气候的响应机理研究"(40771009) （40771009）
