中国岩溶2025，Vol.44Issue(4)：777-789,13.DOI:10.11932/karst2025y008
渝东南纹层石笋δ18O记录的最近100年季风气候变化
Monsoon climate variability over the past century recorded by laminae stalagmite δ18O from southeastern Chongqing,China
摘要
Abstract
This study adopted the stalagmite sample TK22-1 collected from Tiankeng Cave in Youyang Autonomous County,Chongqing,China,as the research object.A high-resolution δ18O sequence spanning the past century was reconstructed through a combination of high-precision 230Th dating and stalagmite laminae counting.This study reveals that the δ18O values of stalagmite TK22-1 exhibited a range of-6.03‰ to-7.29‰,with a mean value of-6.57‰.The positive shifts of δ18O(peaks)correspond well with recorded major drought events in the Sichuan-Chongqing region,such as the 2006 summer drought and the 1960 drought disaster.Correlation analyses show that δ18O variations exhibit a significant positive correlation with annual mean temperature but significant negative correlations with both annual mean humidity and the number of annual precipitation days.Although negatively correlated with total annual precipitation,this relationship does not reach statistical significance.Notably,the δ18O record closely corresponds to local drought events,indicating that regional hydrological conditions-such as temperature,the number of precipitation days,and humidity-are the dominant factors influencing stalagmite δ18O values. The nearly 100-year stalagmite δ18O time series shows distinct phases:δ18O remained consistently negative from 1900 to 1910,shifted to positive between 1910 and 1960,briefly decreased from 1960 to 1970,and have exhibited a consistently positive trend since 1970.Principal component analysis demonstrates that the positive δ18O trend in stalagmites from the Chinese monsoon region is spatially widespread,with a significant weakening observed after 1980.The observed weakening of the Asian Summer Monsoon(ASM)results from a combination of natural variability,such as 11-year solar cycles and Pacific Decadal Oscillation phase shifts,and anthropogenic forcing including greenhouse gases and aerosols.The primary driving mechanisms including ENSO regime transitions,weakening of Atlantic Meridional Overturning Circulation(AMOC)and Pacific Walker Circulation(PWC),and aerosol effects. This trend is significantly associated with global rise in temperature,an increased frequency of extreme ENSO events,and the weakening of both the AMOC and the PWC.Wavelet analysis identifies significant ENSO-related periodicities(2 years to 7 years)in the δ18O record.Between 1960 and 2000,the ENSO system progressively shifted toward El Niño-like states,with Central Pacific(CP)El Niño events suppressing monsoon intensity.The weakening of AMOC reduces land-sea thermal gradients,while the weakening of PWC alters zonal sea surface temperature gradients;together,these changes diminish monsoon dynamics.关键词
石笋/氧同位素/季风气候变化/纹层/影响因素/重庆Key words
stalagmite/oxygen isotope/monsoon climate change/laminae/influencing factor/Chongqing分类
地质学引用本文复制引用
龚萌,杨勋林,葛晓艳,周文明,王思楠,李国凤,向万里..渝东南纹层石笋δ18O记录的最近100年季风气候变化[J].中国岩溶,2025,44(4):777-789,13.基金项目
国家自然科学基金项目(42542054,41971109) （42542054,41971109）
国家重点研发计划子课题项目(2016YFC0502301) （2016YFC0502301）
重庆市自然科学基金面上项目(2023NSCQ-MSX2009) （2023NSCQ-MSX2009）
