• 责任者：Li Guanhua (Key Laboratory of Western China’s Environmental Systems ; Ministry of Education ; Research School of Arid Environment and Climate Change ; Lanzhou University ; Lanzhou 730000 ; China) ; Xia Dunsheng
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(5)
• 关键词：黄土 ; loess ; 环境磁学 ; environmental magnetism ; 天山 ; Tianshan Mountains
• 页码：p.900-910
• 图表：7 illus., 68 refs.
• 分类号：1400
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

     Rock magnetism has played a key role in paleoenvironmental studies for decades and recent 30 years especially saw the rapid progress in environmental magnetic studies of the loess/paleosol sequences all over the world. Previous studies reveal that neither the pedogenic mdoel or the wind vigor model is sufficient to explain variations of magnetic susceptibility of loess from Xinjiang.For example,it has been shown that magnetic characteristics of loess deposits in Xinjiang are controlled by wind vigor model at some intervals but controlled by the pedogenic model in some other intervals.However,most of these results were archived in the Yili valley and few studies have explored magnetic characteristics of the loess deposits in the northern part of the Tianshan Mountain zone.The loess in the northern part of the Tianshan Mountain zone,with a thickness of up to 30~50m,bear important implications for understanding evolution of the Westerlies.In this study,we reported environmental magnetism results of a loess section（Shawan section）in Xia Gobi village,Dongwan town,Shawan county,Xinjiang Uygur Autonomous Region,China.The Shawan section（44°06＇N,85°47＇E; altitude 795m）,with a thickness of about 8m,is located on top of a river terrace and this section can be divided into three layers.The first one is the layer of Holocene soils（0~168cm）.The next part is the loess layer（168~580cm）,which contain a weakly developed paleosol unit（300~350cm）.The third part is paleosols（580~840cm）with a interbedded sandy loess layer（710~780cm）.Samples were collected at 2cm intervals and then pretreated in the laboratory.After that,a systematic study of environmental magnetism was conducted.We found that,like loess from the Chinese Loess Plateau,the ferrimagnetic minerals,magnetite and maghemite,dominate bulk magnetic minerals.A certain amount of incomplete antiferromagnetic minerals（such as hematite and goethite）,with a relatively high concentration in loess layer.were also found.Different from the Loess Plateau,ferrimagnetic materials are primarily multidomain（MD）and pseudo-single domain（PSD）ferrimagnetic minerals.Magnetic susceptibility of the studied section range from 22.00×10-8m3/kg to 127.91×10-8m3/kg,with a median of 44.91×10-8m3/kg.It is interesting that magnetic properties of the upper layer（0~300cm）have positive correlations with degree of pedogenesis,which was responsible for the increase of the fine grained magnetic minerals.In contrast,magnetic properties of the lower section（from 300~840cm）have good correlation with wind intensity.We suspect that pedogenesis might have significant effect on magnetic properties of the studied section as wind strength was relatively weak and when wind was strong,magnetic proporties of loess in the studied section is dominated by wind intensity.We propose that ratio of anhysteretic remanent magnetization to saturation isothermal remanent magnetization（XARM/SIRM）is probably more appropriate than magnetic susceptibility to represent degree of the local pedogenesis.