桂林地区近150年来的气候变化——基于^(210)Pb计年的洞穴碳酸盐沉积物记录  

CLIMATE CHANGE DURING THE LAST 150 YEARS IN GUILIN——RECORDED BY ISOTOPES OF^(210)Pb DATED SPELEOTHEMS IN PANLONG CAVE

作　　者：王华[1] 覃嘉铭[1] 杨琰[2] 孙海龙[3] 林玉山[1] 应启和[1] 

机构地区：[1]中国地质科学院岩溶地质研究所岩溶动力学重点实验室,桂林541004 [2]西南大学地理科学学院,重庆400715 [3]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002

出　　处：《第四纪研究》2009年第5期943-949,共7页Quaternary Sciences

基　　金：科技部基本科研业务费所控项目(批准号:200718)资助

摘　　要：采用 ^(210)Pb定年和碳、氧稳定同位素分析方法对盘龙洞内的洞穴次生碳酸盐沉积物进行了系统研究,重建桂林地区近150年来的气候变化。本文采用的次生碳酸盐沉积物是采自桂林盘龙洞中的P001石笋和P007流石,分别获得9个和12个 ^(210)Pb测年数据;以及41个和46个碳、氧同位素数据。P001石笋碳、氧同位素记录年代跨度为公元1869～2002年,δ^(18)O平均值为-6.28‰,δ^(13)C平均值为-7.59‰;P007流石碳、氧同位素记录跨度为公元1854～2004年,δ^(18)O平均值为-5.27‰,δ^(13)C平均值为-6.68‰。P001石笋和P007流石碳、氧同位素记录的低频信号显示出一致的变化趋势,而且二者的δ^(13)C曲线相对δ^(18)O曲线一致性更强,说明它们受同样环境条件所制约,同时也说明了其 ^(210)Pb年代系列的建立是可靠的。盘龙洞石笋和流石的δ^(18)O和δ^(13)C记录在公元1930～1965年都出现一个低谷,表明该时段植被生产力相对减弱,亦即降水相对减少。通过P001石笋和P007流石的碳、氧同位素记录与现代降雨记录的比较可知,在年际至10年际尺度上,氧同位素反映的为降水或者季风的强弱。由此,公元1854年到2005年的151年内,盘龙洞碳酸盐沉积物氧同位素所反映的气候变化信息为3个阶段:1)1854年至1900年的相对较强季风期,降水量较丰,δ ^(18)O平均值为-6.3‰;2)1900年至1960年的较弱季风期,降水量较少,δ ^(18)O平均值为-5.1‰;3)1960年至2005年的较强季风期,降水量较丰富,δ ^(18)O平均值为-6.1‰。Speleothem samples from Panlong Cave（24°59′N, 110°22′E） in Guilin, South China, i. e., stalagmite P001 and flowstone P007 ,provide a nearly continuous record of climate change over the last 150 years. Stalagmite P001 yield 41 oxygen and carbon isotopic values and nine ^210Pb dating data,while flowstone P007 yield 46 isotopic xygen and carbon and twelve ^210Pb dating data. The time interval recorded by stalagmite P001 oxygen is from 1869 to 2002 A. D. ： the δ^18O average is -6.28‰ and the δ^13C average is -7.59‰. The time interval recorded by flowstone P007 is from 1854A. D. to 2007 A. D. ： the δ^18O average is -5.27‰ and the δ^13C average is -6.68‰. In the carbon and oxygen isotope records of stalagmite P001 and flowstone P007, their low-frequency signals show a consistent trend. Furthermore,their δ^13C curves are more obvious in consistency than their δ^18O curves. These mean that they should be subject to the same environmental condition,and that their ^210Pb ages series should be reliable. The δ^180 and δ^13C curves of stalagmite P001 and flowstone P007 all have a low valley in 1930 - 1965 A. D. , indicating that the productivity of vegetation should be relatively low in this period and that the precipitation should be relatively less. By comparing the carbon and oxygen isotope records of stalagmite P001 and flowstone P007 with the modern rainfall amount, it can be seen that the oxygen isotopes reflects the strength of precipitation or monsoon in annual to decadal time scale. Over the last 151 years from 1854A. D. to 2005A. D. , three periods can be approximately divided in terms of climate change reflected by δ^18O values：（ 1 ）1854 to 1900,in which the monsoon was stronger and the rainfall was very rich, with the δ^18O average to be -6.3‰;（2）1900 to 1960, in which the monsoon became weak and the rainfall decreased, with the δ^18O average to be -5.1‰; and （3） 1960 to 2005, in which the monsoon became stronger and the rainfall was very rich,with the δ^18O aver

关 键 词：洞穴次生碳酸盐沉积物 ^210PB 稳定同位素 气候变化 桂林 

分 类 号：P532[天文地球—古生物学与地层学] P597[天文地球—地质学]