临夏塬堡全新世黄土剖面古土壤有机质碳同位素的气候记录

The Climatic Record of Organic Matter in the Paleosol from the Yuanbao Holocene Profile

对甘肃临夏塬堡全新世剖面古土壤有机质碳同位素分析表明 ,δ13 C变化范围在 - 2 8.2 3‰～2 5 .19‰之间 ,平均值为 - 2 6 .88‰ .结合该剖面孢粉分析结果 ,观察到在孢粉所反映的温暖湿润气候期间 ,δ13 C表现为高值 ,而在干燥寒冷期间 ,δ13 C表现为低值 .说明由于气候变化引起了地表植被类型的改变 ,导致了古土壤中有机质δ13 C发生了变化 .δ13 C的变化特征分别对应于 3个不同的气候演化阶段 :早全新世、中全新世和晚全新世阶段 ,其所反映的全新世气候特征与我国其它地区的分析结果基本一致 .分析表明 ,古土壤中有机质δ13 C是气候变化的一个良好指标 .

On the basis of the carbon isotope analysis of organic matter in the paleosol from the Yuanbao Holocene Profile, the values of δ\+\{13\}C are observed between \{-28.23\}～\{-25.19‰\}, with the average of \{-26.88‰\}. Combining the pollen record, it is found that the higher values of δ\+\{13\}C corresponds to warm and humid climate condition, and the lower values corresponds to cold and arid climate condition, which suggests that the climate change has resulted in the changes in δ\+\{13\}C and vegetation types. Three Holocene stages can be recognized from the variation in the characteristics of \{δ\+\{13\}C\} in the Yuanbao Holocene Profile. The Holocene climate features recorded in the profile were similar with those in other places of China. The carbon isotope of organic matter in the paleosol is also suggested as an indicator for climate change.