Loess Chronology And Weathering Features Of The South Of Liaoning

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.