作　　者： ;

机构地区： 中山大学地球科学与工程学院

出　　处： 《古地理学报》 2019年第5期855-868,共14页

摘　　要： 大洋沉积物中的风尘记录良好地揭示了风尘源区干旱化过程和季风强度变化。以位于西太平洋采薇海山附近的柱状沉积物(MABC19孔)为研究对象,在基于地磁场相对古强度对比获取年代框架的基础上,从沉积物粒度组分和磁学参数中提取研究区~80 ka以来风尘物质的记录。沉积物高矫顽力磁性矿物参数结果指示,研究区风尘输入量自~80 ka以来总体呈逐渐增加趋势,在MIS3/MIS2转换阶段风尘输入量增加明显,揭示了风尘源区古气候条件的转变。通过碎屑沉积物粒径-标准偏差方法提取代表风尘输入的敏感组分,其平均粒径记录了东亚冬季风强度在MIS3/MIS2转换阶段显著增大,该记录与黄土地区风尘记录指示的东亚冬季风强度变化在MIS3阶段高度一致,在其余时段存在着差异,初步推测这是由于高空风尘输送机制的海、陆差异所致。 Eolian records in marine sediments were suggested to reveal the drying process in dust sources area and the variations of the intensity of monsoon. Here we present the eolian records since ~ 80 ka deduced from grain size and rock magnetic analysis of a sediments core( Core MABC19) near the Caiwei Seamounts,Western Pacific. The chronostratigraphy of the core was constructed by the relative palaeointensity( RPI) of the earth’ s magnetic field. According to the variations of the high coercivity magnetic mineral parameters,the eolian input into the study area increase gradually since ~ 80 ka,and reach relatively high level during the MIS3/MIS2 transition,indicating the variations in palaeoclimate and palaeoenvironment conditions in the dust source area. The average grain size of eolian component derived from grain size-standard deviation method is used as an indicator of the intensity of East Asian winter monsoon( EAWM). The average grain size data reveals a significant increase of EAWM during the MIS3/MIS2 transition,which is highly consistent with the variation of EAWM intensity indicated by loess during MIS3 stage. However,differentiation is apparent in the rest periods. The maritime-continental contrast of the dust transportation mechanism at high altitude is likely to contribute to this difference.

关 键 词： 风尘沉积 西太平洋 东亚冬季风 海陆对比

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