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马厂剖面中黄土-古土壤序列共厚15.5m,根据岩性、磁性地层特征、磁化率、CaCO3含量和光释光测年结果,将金川黄土划分为冰后期S0古土壤,末次冰期L1黄土,末次间冰期S1古土壤、倒数第二冰期L2黄土和倒数第二间冰期S2古土壤等5个地层单位;其中,S1复合型古土壤又可细分为S1LL1、S1LL2黄土和S1SS1、S1SS2和S1SS3古土壤等5个次级地层单位。金川黄土沉积始于中更新世晚期,其底界的年龄大致为200kaBP,其磁化率变化反映了最近200ka来的高原季风演化和气候环境变迁,5个磁化率高值段指示了5个夏季风环流增强的时段,4个磁化率低值段则代表了4次夏季风减弱的时期。
According to lithology, magnetic stratum characteristics, magnetic susceptibility, CaCO3 content and light-induced luminescence dating, Jinchuan loess is divided into S0 paleosol in late ice period, L1 loess in the last glacial period, S1 paleosol in the last interglacial period, L2 loess in the penultimate glacial stage and S2 paleosol in the penultimate glacial stage. Among them, the S1 complex type paleosol can be subdivided into S1LL1, S1LL2 loess and S1SS1, S1SS2 and S1SS3 Paleosol 5 sub-strata units. The sediments of Jinchuan loess began in the late Mid-Pleistocene with the age of its bottom boundary being about 200kaBP. The change of its susceptibility reflects the evolution of plateau monsoon and climate in the recent 200 ka. The period of enhanced circulation and the low value section of 4 magnetic susceptibility represent the periods of 4 weakened summer monsoons.