Mineral magnetic variation of the Jingbian loess/paleosol sequence in the northern Loess Plateau of China:Implications for Quaternary development of Asian aridification and cooling
作者单位：Geomagnetism LaboratoryDepartment of Earth and Ocean SciencesUniversity of LiverpoolLiverpool L69 7ZEUK
会议名称：《中国科学院地质与地球物理研究所2006学术年会》
会议日期：2007年
学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学]
关 键 词：Chinese Loess Plateau loess paleosol mineral magnetism magnetoclimatology Asian aridification and cooling
摘 要：A high-resolution mineral magnetic investigation has been carried out on the Jingbian loess/paleosol sequence at the northern extremity of the Chinese Loess *** show that the magnetic assemblage is dominated by large pseudo-single domain and multidomain-like magnetite with associated maghemite and *** in the ratios of SIRMT/SIRM, SIRM/SIRM and SIRM/SIRM(SIRM is the saturation isothermal remanent magnetization;SIRM represents the residual SIRM after an n mT alternating field demagnetization) have been used to document regional paieoclimate change in the Asian interior by correlating the mineral magnetic record with the compositeδO record in deep-sea sediments. The long-term up-section decreasing trend in those ratios in both loess and paleosol units has been attributed to a long-term decrease in the relative contributions of eolian hematite during glacial extrema and of pedogenic hematite during interglacial extrema,respectively,which reveals a long-term decreasing trend in chemical weathering intensity in both glacial-stage source region (the Gobi and deserts in northwestern China) and interglacial-stage depositional area(the Loess Plateau region).We further relate this long-timescale variation to long-term increasing aridification and cooling,during both glacial extrema in the dust source region and interglacial extrema in the depositional area,over the Quaternary *** in those ratios are most likely due to Quaternary aridification and cooling driven by ongoing global cooling,expansion of the Arctic ice-sheet,and progressive uplift of the Himalayan-Tibetan complex during this period.