古气候变化的石笋同位素记录研究——以桂林盘龙洞为例

本文以桂林盘龙洞的研究工作为例，选择大型石笋剖面，在沉积学分析学研究的基础上，采用目前最先进的测年技术———ＡＭＳ１４Ｃ法，配合Ｕ系及稳定同位素地球化学综合手段，系统提取气候信息，建立了桂林地区３．６万ａ来气候变化的基本模式。该区末次冰期３．２～３．６万ａ时，年平均气温最低８～９℃。全新世在总的暖和、潮湿气候背景下，可划分出由暖到冷的３个气候旋回，每个旋回持续约３０００ａ左右，暖期年平均气温高于现今３～４℃，冷期低于现今３℃左右，可鉴别的次一级冷期可与我国５０００ａ物候记录资料进行对比。

Studies on Stalagmite Isotope Records of Paleoclimatictic Changes

More than two years''monitoring to the nowadays water_drop and carbonate sedimentation as well as the cave environment around a big stalagmite at the Panlongdong cave in Guilin has been conducted for the detaild study. It provides a basis for testing the balanced sedimentation of isotope and full exchange degree of 14 C.Meanwhile,the systematic and comprehensive studies with AMS 14 C,U series and stable isotope have been made along the axis cores of the stalagmites.A model has been presented for the climate changes in the past 36 000 as in Guilin area. The records of oxygen isotope of the stalagmites are basically consistent with the climate in-formation provided by the carbon isotope and the growth rate of stalagmite. They can also be compared with the results of the study of phenology in our country and the section of loess in northern China.