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对青藏高原东北部青海拉拉口、盘子山和东川等地的黄土-古土壤样品进行的磁化率、频率磁化率、X-T曲线、饱和等温剩磁和磁滞回线等测试分析结果表明,晚第四纪青藏高原东北部风尘堆积黄土和古土壤中的磁性矿物都以磁铁矿为主,还有磁赤铁矿和赤铁矿.古土壤中的磁赤铁矿含量高于黄土,说明在成壤过程中除了形成赤铁矿外,还新生成了磁赤铁矿,这些土壤成因的磁赤铁矿使古土壤磁化率明显增强.这与六盘山以东黄土高原的黄土-古土壤具有相似的特征.另一方面,青藏高原东北部的黄土层和古土壤层中的亚铁磁性矿物的平均粒度都是准单畴,但黄土层中亚铁磁性矿物的平均粒度较粗,明显偏向多畴区域.研究区黄土-古土壤序列的磁化率高低与超顺磁颗粒的含量和土壤发育强度基本呈正相关.气候作用是主导高原黄土-古土壤磁化率增强的主要因素,即温湿气候增强土壤化作用,从而导致磁化率增强.
The results of magnetic susceptibility, frequency susceptibility, XT curve, saturated isothermal remanent magnetization and hysteresis loop of loess-paleosol samples from Qinghai Larakou, Panzishan and Dongchuan in the northeastern Qinghai-Tibet Plateau show that, Late Quaternary Qinghai-Tibet Plateau dust accumulation in the Loess and ancient soil magnetic minerals are mainly magnetite, as well as maghemite and hematite.The ancient soil maghemite content is higher than the loess, Which indicates that in addition to the formation of hematite in the process of pedogenesis, maghemite is also newly formed, and the magmatic hematite of these soils has markedly increased the susceptibility of the paleosol to the paleosol. This is consistent with the loess-paleo On the other hand, the average size of ferrimagnetism minerals in the loess and palaeosol layers in the northeastern Qinghai-Tibet Plateau are quasi-single domain, but the average grain size of ferrimagnetic minerals in the loess layer is coarse, And obviously biased toward multidomain regions.The magnetic susceptibility of the loess-paleosol sequence in the study area is positively correlated with the content of superparamagnetic particles and soil development strength.Climatic effect is the main factor that leads the increase of susceptibility of paleosol in the plateau, moisture Enhancement of the role of the soil, leading to enhanced susceptibility.