Oxygen and carbon isotopic characteristics of rainwater,drip water and present speleothems in a cave in Guilin area,and their environmental meanings  

作　　者：李彬 袁道先 覃嘉铭 林玉石 张美良 

机构地区：[1]Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China

出　　处：《Science China Earth Sciences》2000年第3期277-285,共9页中国科学（地球科学英文版）

摘　　要：The studies of the oxgen and carbon isotopes of the rainwater in Guilin area, the drip water and the present carbonate deposit in Panlong cave of Guilin show that: (i) as to the general characteristics of the oxygen isotopes of the rainwater within a year and between years, the δ18O values decrease with an increase of air temperature and the rainfall, and the correlation between δ18O values and the mean monthly air temperature is much better than that between δ18O values and the rainfall, and the δ18O values of the rainwater during the summer monsoon are much smaller than those during winter monsoon; (ii) δ18O values of the drip water have a quite good correlation with the δ18O values of the rainwater in the same period; (iii) when the conditions are appropriate, δ13C can be used as an environmental proxy, that is, the smaller δ13C of speleothems is, the larger the proportion of C3 plants is and the more plentiful the rainfall is. On the contrary, C4plants may be prevailing or the environment may be a stony desert caused by climate changes or human activity.The studies of the oxgen and carbon isotopes of the rainwater in Guilin area, the drip water and the present carbonate deposit in Panlong cave of Guilin show that: (i) as to the general characteristics of the oxygen isotopes of the rainwater within a year and between years, the δ18O values decrease with an increase of air temperature and the rainfall, and the correlation betweenδ18O values and the mean monthly air temperature is much better than that between δ18O values and the rainfall, and the δ18O values of the rainwater during the summer monsoon are much smaller than those during winter monsoon; (ii) δ18O values of the drip water have a quite good correlation with the δ18O values of the rainwater in the same period; (iii) when the conditions are appropriate, δ13C can be used as an environmental proxy, that is, the smaller δ13C of speleothems is, the larger the proportion of C3 plants is and the more plentiful the rainfall is. On the contrary, C4 plants may be prevailing or the environment

关 键 词：RAINWATER CAVE drip water PRESENT speleothem OXYGEN and CARBON isotopes environmental meanings. 

分 类 号：P641.3[天文地球—地质矿产勘探]