贵州七星洞晚更新世晚期石笋的古气候环境记录  

THE PALEOCLIMATIC RECORDS FROM THE LATE PLEISTOCENE STALAGMITE IN GUIZHOU QIXING CAVE

作　　者：彭子成[1,2] 张兆峰[1,3] 蔡演军[2] 张美良[4] 林玉石[4] 刘桂建[1] 

机构地区：[1]中国科学技术大学地球和空间科学系,合肥230026 [2]中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,西安710054 [3]南京大学地球科学系,桂林541004 [4]中国地质科学院岩溶地质研究所

出　　处：《第四纪研究》2002年第3期273-282,共10页Quaternary Sciences

基　　金：国家重点基础研究发展规划项目 (批准号 :1 9990 4 34 0 0 );中国科学院知识创新工程重大项目 (批准号 :KZCXI-Y -0 5 );中国科学技术大学资源与环境研究基地项目

摘　　要：用热电离质谱 (TIMS) -铀系法高精度地测定了贵州七星洞石笋的年龄 ,其生长年限为 43 0 2 0± 96 0～ 1 2 6 5 0± 2 90aB .P .,相当于深海氧同位素 2阶段到 3阶段后期。石笋的生长率变化反映了当时气候从暖湿多雨和印度洋季风强劲的环境 ,逐渐转化为冷干少雨、东亚冬季风强劲的环境。石笋的氧同位素变化表明 :43 0 0 0～ 2 96 0 0aB .P .相当于深海氧同位素 3阶段后期。该阶段δ18O平均值负于全阶段的平均值 ,气候暖湿多雨 ,此青藏高原夏季出现强的低气压 ,有利于印度洋季风携带孟加拉湾大量水汽进入青藏高原 ;2 96 0 0～ 1 46 0 0aB .P .相当于深海氧同位素 2阶段 ,该阶段δ18O平均值高于全阶段的平均值 ,气候冷干少雨 ,对应于末次盛冰期 ;1 46 0 0～ 1 2 6 5 0aB .P .阶段δ18O平均值略负于全阶段的平均值 ,气候向温湿趋势发展。石笋氧同位素曲线还显示了HeinrichH1 ,H2 ,H3和H4的突冷事件和Dansgaard Oeschger(D O)IS1～IS1 1的暖事件旋回 ,这表明北大西洋发生的气候突发事件 ,在低纬度的贵州地区找到了印记。大西洋环流的终止和产生 ,可以通过大气内部的动力过程 ,影响到亚洲季风控制区。对于表征全球变化的事件是否具有同时性 ,还有待我们思考和研究。On the basis of the measurement by using thermal ionization mass spectrometry U series method, the ages of the stalagmite from the Guizhou Qixing cave ranged 43 020±960～12 650±290aB.P.,corresponding to MIS2 and the late of MIS3. The oxygen isotopic variability of the stalagmite revealed that the paleoclimatic changes can be divided into several stages: in the first stage (43 000～29 600aB.P.), corresponding to the late of MIS3, the δ 18 O values were generally lower than the average, and the climate was warm wet and much rainy, which was agreement with the background of the low pressure in the Qinghai Xizang Plateau and the large amount of the vapor from Bengal Bay into this areas by the driving force of the Indian monsoon; in the second stage (29 600～14 600aB.P.), corresponding to MIS2, the δ 18 O values were higher than the average, the climate was cold dry and less rainy, which was consistent to the background of the maximum stage of the last glacial period; in the third stage 14 600～ 12 650 aB.P. corresponding to the late of MIS2 and the early of MIS1, the δ 18 O values were just lower than the average, the paleoclimate was getting warm wet. As compared to the records of the Greenland oxygen isotopes (GISP2), the δ 18 O curve of the Guizhou stalagmite showed that the Heinrich events 1,2,3,4 and the Dansgaard Oeschger IS1～IS11 warm events had been also recorded in the growth period of the stalagmite. $$$$

关 键 词：贵州 石笋 热电离质谱-铀系年龄 生长率 氧同位素 古气候环境 晚更新世 

分 类 号：P532[天文地球—古生物学与地层学]