The Younger Dryas Event and Holocene Climate Fluctuations Recorded in a Stalagmite from the Panlong Cave of Guilin

: Comprehensive studies on a stalagmite from the Panlong cave, Guilin, have shown that the isotopic records and sedimentary characteristics can reflect the changes of both palaeotemperatures and palaeorainfall, that is to say, it is possible to get some information about the changes in climate of the area from the speleothem. The results suggest that: (1) the Younger Dryas event might have persisted in the area from 11 300 to 10 800 a B.P.; (2) from 9000 to 7000 a B.P., the climate got warmer and wetter, and the summer monsoon was gradually enhanced; (3) from 7000 to 4500 a B.P., the climate was warm and wet, and the summer monsoon prevailed; and (4) from 4500 a B.P. on, the summer monsoon was weakened and the modern climate pattern appeared, but there were several cold and dry periods, namely, from 4000 to 2500 a B.P., ca. 2400 a B.P. and < 1000 a B.P.

桂林水南洞洞穴沉积物的古地磁记录及其古环境意义

通过对桂林水南洞２．５ｍ厚的洞穴沉积物剖面的古地磁初步研究，其结果及地质证据表明该沉积剖面形成期可能与贾拉米洛正向期对应。根据磁化率、磁性矿物的特征和沉积学特征，对该地区这一地质时期的古环境变化提出以下认识：１．第三暖湿期，以钙华沉积为特征；２．第二干冷期，以含有少量钙质的黄褐色粘土为特征，并以含有高矫顽磁性矿物和低磁化率为特征；３．第二暖湿期，以互层的红褐色粘土、含高含量钙质的粘土或钙华为特征，并以含有低矫顽磁性矿物和高磁化率为特征；４．第一干冷期，以褐灰色粘土为特征，并以含有高矫顽磁性矿物和低磁化率为特征；５．第一暖湿期，以地下河沉积相（砂卵石为主）为特征。