【摘要】 湖泊中的有机碳及其同位素与磁化率指标广泛应用于古气候的重建,但由于各地自然条件的差异,其气候意义具有一定的区域性。对江汉平原江陵剖面沉积物中磁化率参数、总有机碳(TOC)、总氮(TN)及其碳同位素δ(13C)值影响因素与环境气候关系的研究结果表明沉积物总有机碳(TOC)的变化与总氮(TN)呈正相关关系,而总有机碳(TOC)与同位素δ(13C)、磁化率值则呈负相关关系,其组合可以很好地反映江汉平原地区的环境演变。在暖湿期,沉积物中总有机碳、总氮较高,有机质的δ(13C)值偏负,磁化率偏低;反之,在凉干期,沉积物中总有机碳、总氮较低,有机质的δ(13C)值偏正,磁化率偏高。江汉平原地区6000aPB以来的古气候演化经历了3个阶段即冷干—暖湿—凉干的变化过程。更多还原

【Abstract】 The data of carbon isotope in organic matter and magnetic susceptibility of lacustrine sediment are extensively used to reconstruct the paleoclimatic change. Because the natural environment varies in different regions, the climatic significance of carbon isotope in organic matter and magnetic susceptibility of lacustrine sediment is regional to a certain extent. This paper analyses the influencing factor of organic matter TOC、TN and δ( 13 C) value and magnetic susceptibility with samples from Jianghan plain,Hubei Province, and discusses its relationship with climatic circumstance. The results show that: TOC and TN have positive correlation, but TOC、δ( 13 C) and magnetic susceptibility have negative correlation. The organic carbon isotope and total organic carbon and magnetic susceptibility could display the environment change distinctively. During warmer and wetter climatic episodes, the values of TOC and TN of the organic materials in sediments are higher, but the values of δ( 13 C) and magnetic susceptibility are lower. On the other hand, during colder and dryer climatic episodes, the values of TOC and TN contents in sediments are lower; the values of δ( 13 C) and magnetic susceptibility are higher. These results enable the authors to reconstruct the evolution sequence of paleoclimate in Jianghan Plain region since 6 000 a BP. It has three stages:6 070-4 600 a BP, when the climate was cold and dry; 4 600-2 500 a BP, when the climate was warm and wet; and 2 500-500 a BP, when the climate was cool and dry.更多还原