【作者】 李大鹏；

【导师】 张威；

【作者基本信息】 辽宁师范大学 ， 第四纪地质， 2012， 硕士

【摘要】 本文依托辽南地区七顶山黄土沉积剖面，对黄土年代地层进行光释光（OSL）测年研究，并对剖面的常量元素进行测试，结合古地磁数据资料等，并与东部丘陵平原区已有研究进行比较，系统地分析了黄土地层年代学特征及风化特征。年代学结果表明，七顶山黄土堆积的开始时代为中更新世早期。相当于黄土高原的马兰黄土堆积时代为晚更新世，离石黄土与马兰黄土的分界年代为100-110ka左右，这与黄土高原的研究结论相一致，反映地球轨道参数控制的气候变化。马兰黄土的堆积时间集中在末次冰期（MIS4-5d）的早期和晚期（MIS2），对应时代为22-31ka和86-113ka，而在末次冰期中期（MIS3），由于较高的气温和丰沛的降水及地势条件的影响，造成本区大约4-5万年的地层缺失。中国东部丘陵平原区年代地层学研究显示马兰黄土堆积是比较连续的，具体原因有待进一步深入探讨。风化特征结果表明：辽南地区黄土中的SiO₂、Al₂O₃、TFe₂O₃的含量明显高于陕西洛川黄土，MgO、CaO、Na₂O含量明显低于洛川黄土，而与镇江下蜀黄土和洛川古土壤的含量比较接近，K₂O、MnO、TiO₂含量各地比较一致，P₂O₅的含量明显低于洛川和镇江；辽南地区黄土的化学风化基本完成早期去Na、Ca风化过程，并进入中期去K、Si风化阶段；七顶山黄土剖面元素的迁移和富集在马兰黄土和离石黄土中表现完全不同，说明辽南地区在中更新世晚期和晚更新世气候发生明显的变化，由暖湿的气候环境突变为冷干的气候环境。化学风化程度由强至弱依次为：镇江下蜀黄土、陆源页岩、辽南地区、洛川黄土（酸不溶相）、洛川黄土（全样）、上部陆壳。镇江下蜀黄土的化学风化程度最强，辽南地区黄土的风化程度略高于酸不溶相的洛川黄土，而明显大于全样的洛川黄土，主要差异来源于风化过程中不同的气候条件以及粒度效应。更多还原

【Abstract】 Depending on the samples from the typical loess profile of Qiding shan in the south ofLiaoning, apply optically stimulated luminescence （OSL） to loess layer and test on macroelement of the loess profile, combined with the data of paleomagetic and so on, comparedwith existing reference of hills and plain regains in eastern China, analyzing the loess layerchronology features together with the weathering features in details.The results show that the origin of the loess accumulation of Qidingshan was from the earlystage of the middle Pleistocene, while the Malan loess accumulated since the100-110ka. It isconsistent with the studies in loess plateau, indicatinge the climate change was controlled bythe earth orbital parameter. During the last glacial cycle, the Malan loess was mainlydeposited in the early（MIS4-5d）and late（MIS2） stage of the last glacial cycle, respectivelycorresponding to the absolute OSL ages22-31ka and86-113ka.Due to the higher temperature, plentiful precipitation and topography condition, there is about40-50ka loess layer absence in Qidingshan profile during the middle part of the last glacialcycle （MIS3）. Loess layer chronology on hills and plain regains in eastern China reveal thatthe accumulation of Malan loess is relatively successive, however, the reason request furtherstudy. we systematacially analyze the weathering features in the profile of loess in Qidingshan,the results show that the contents of SiO₂,Al₂O₃,TFe₂O₃in the south of Liaoning province areobviously larger than that of Luochuan in Shanxi province, while the contents MgO、CaO、Na₂O in the south of Liaoning province are lower than that of Luochuan loess in Shanxiprovince, moreover, they are nearly to the loess in Zhenjiang and paleo-soil in Shanxiprovince. The change of K₂O、MnO、TiO₂is not obviously in the relative regions, while thecontent of P₂O₅is lower than that of Zhenjiang; the process of the chemical weathering in thesouth of Liaoning province happed not only leaching the Na and Ca, but also leaching the Kand Si in some scale. The chemical weathering has already finished early stage of leaching Naand Ca, furthermore, it has entered the middle and late stages of leaching K and Si comparedwith the elements migration in the loess of Luochuan; The migration and accumulation aredifferent in the Lishi and Malan loess in the Qidingshan profile. The evolution of the chemicalelements in the profile indicates that the environment changed abruptly form warm and humidclimate in the middle Pleistocene to cold and dry climate in the late Pleistocene. The chemicalweathering intensity in these study regions are the xiashu loess>PAAS> the south of Liaoning>Luochuan loess （not including the acid dissolution components）>Luochuan loess（total samples）>UCC. All these differences were caused by the different climate conditionsand Particle size effect during the process of weathering.更多还原