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黄土高原东南部地区是受东亚冬季风搬运的巨厚粉尘沉积的末端区域,亦是东亚夏季风向亚洲内陆深入的前缘区域.本研究选择这一古气候敏感区的第四纪黄土-古土壤沉积剖面作为研究载体,多重磁学参数的解译反演了风成沉积所记录的1.95~0.40 Ma间粉尘源区和沉积区的古气候演变历史.结果表明,参数HIRM/(SIRM-IRM100 mT)沿全剖面向上的减小趋势,可能记录了沉积物中赤铁矿矫顽力长期趋于减小,我们认为其主要反映了间冰期沉积区和冰期粉尘源区环境的冷干化发展态势;而常被用于反映磁性矿物粒度变化的参数lf/ARM在此期间表现为长期的增大趋势,体现了磁性矿物粒度趋向于增大化,很可能反映了控制次生成壤强度的东亚夏季风同期整体变弱的趋势.虽然其他磁学参数同时记录了古气候的区域性多段变化特点,但沉积物中蕴含的亚洲古气候长期冷干化发展趋势具有全球性的对比意义.
The southeastern part of the Loess Plateau is the end of the thick sediment transported by the East Asian winter monsoon and the leading edge of the East Asian summer monsoon to the interior of Asia. In this study, the Quaternary loess-paleozoic Soil sedimentary profile was used as a research carrier and interpretation of multiple magnetic parameters retrieved the history of paleoclimate evolution from 1.95 to 0.40 Ma recorded by aeolian deposition.The results show that the parameters HIRM / (SIRM-IRM100 mT) tends to decrease upward along the whole profile, and may indicate that the coercivity of hematite in sediments tends to decrease for a long period of time. We think it mainly reflects the cold and dry development of the environment in the sedimentary and glacial source regions While the parameter lf / ARM, which is often used to reflect the change of magnetic mineral grain size, shows a long-term increase trend during this period, which shows that the magnetic mineral grain size tends to increase, probably reflecting the East Asian While the monsoon tends to weaken as a whole in the same period of the summer monsoon.Although the other magnetic parameters record the characteristics of regional multi-stage changes of paleoclimate simultaneously, the long-term cold-dry development trend of paleoclimate in Asia Ballistic contrast.