干旱区生态环境知识资源中心(Arid): 兰州九州台黄土磁性特征及其古气候意义研究

Arid

	兰州九州台黄土磁性特征及其古气候意义研究
其他题名	MAGNETIC PROPERTIES OF JIUZHOUTAI LOESS IN LANZHOU AND ITS SIGNIFICANCE OF PALAEOCLIMATE
	刘现彬 1; 夏敦胜 2; 贾佳 1; 魏海涛 1; 赵爽 1; 李冠华 1; 于英鹏 3
来源期刊	第四纪研究
ISSN	1001-7410
出版年	2012
卷号	32 期号:4 页码:761-770
中文摘要	本文选取黄土高原西部地区具有代表性的九州台黄土进行系统的磁性和粒度特征研究,结果表明其磁性特征主要由磁铁矿控制,同时含有磁赤铁矿和赤铁矿;磁性矿物粒度为假单畴,黄土的粒度组成以粉砂为主。<2mum的细颗粒组分不能很好的反映黄土高原西部地区黄土末次间冰期的成壤强度。与磁化率相比,X_(ARM)/X_(lf)和X_(ARM)/SIRM能更好的反映成壤强度和古气候变化。选取>40mum的粒度百分含量和X_(ARM)/SIRM作为代用指标分别反映冬、夏季风变化,研究结果揭示冬、夏季风趋势并非同步异向变化,在倒数第二次冰期向末次间冰期过渡时,相对于夏季风,冬季风的变化具有一定的滞后性,暗示了冬夏季风的主控因素可能不同。
英文摘要	Lanzhou is located at the intersection of the Qinghai-Tibet Plateau,the Loess Plateau and the northwest desert region,which is also the junction of the three natural belts including the eastern monsoon region,western arid and semi-arid regions and the Qinghai-Tibet alpine region.In this study,we investigated the Jiuzhoutai loess section(36.05°N,103.88°E;2056m a.s.l.)which is situated at the sixth-level terrace of north shore of the Yellow River in Lanzhou City and is the most representative loess sequences in the western Chinese Loess Plateau. S_1 is about 29~36m below the surface,which can be clearly identified with two layers of loess(S_1L_1 and S_1L_2)and three layers of paleosols(S_1S_1,S_1S_2 and S_1S_3).The pedogenisis intensity is the strongest in S_1S_3.Two hundred and twenty samples were obtained in S1 paleosol and its upper and lower loess(about 27~38m)by 5cm intervals. We carried out systemic rock-magnetic investigations including low-frequency magnetic susceptibility(X_(lf)),high-frequency magnetic susceptibility(X_(hf)),anhysteretic remanent magnetization(ARM),isothermal remanent magnetization(IRM),saturation isothermal remanent magnetization(SIRM),hysteresis loop and magnetization curves on all samples.Particle size was also measured by a Mastersize 2000 Laser diffraction particle size analyzer.Results show that the main magnetic minerals of the loess deposit are magnetite,maghaemite,haematite,and the main magnetic grain size of magnetic minerals are PSD.The grain sizes of loess is composed mainly of silt and fine particles cannot reflect pedogenesis of loess very well in West Loess Plateau in the Last Interglacial.There exists a threshold of 30*10~(-8) m~3/kg of the magnetic susceptibility in the western Chinese Loess Plateau.Above the threshold,there is a good positive correlation between magnetic susceptibility and pedogenisis strength and magnetic susceptibility reflect paleoclimate after the sediments deposition.Below the threshold,the magnetic susceptibility may reflect paleoclimate of loess source area.Compared with susceptibility, X_(ARM)/SIRM and X_(ARM)/X_(lf) respond to the strength of pedogenesis and paleoclimate more accurately.The trends of parameters of magnetic and grain-size properties indicate that the changes of winter and summer monsoon were not completely reverse.Relative to the summer monsoon,winter monsoon has a certain lag in the period of transition between penultimate glaciation and the Last Interglacial.The drives of summer and winter monsoon may be different.
中文关键词	黄土 ; 环境磁学 ; 冬季风 ; 夏季风
英文关键词	western Loess Plateau loess environmental magnetism winter monsoon summer monsoon
语种	中文
国家	中国
收录类别	CSCD
WOS类目	GEOSCIENCES MULTIDISCIPLINARY
WOS研究方向	Geology
CSCD记录号	CSCD:4669160
来源机构	兰州大学
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/227921
作者单位	1.兰州大学西部环境与气候变化研究院, 西部环境教育部重点实验室, 兰州, 甘肃 730000, 中国; 2.兰州大学西部环境与气候变化研究院, 西部环境教育部重点实验室;;中国科学院沙漠与沙漠化重点实验室, 兰州, 甘肃 730000, 中国; 3.兰州大学资源环境学院, 兰州, 甘肃 730000, 中国
推荐引用方式 GB/T 7714	刘现彬,夏敦胜,贾佳,等. 兰州九州台黄土磁性特征及其古气候意义研究[J]. 兰州大学,2012,32(4):761-770.
APA	刘现彬.,夏敦胜.,贾佳.,魏海涛.,赵爽.,...&于英鹏.(2012).兰州九州台黄土磁性特征及其古气候意义研究.第四纪研究,32(4),761-770.
MLA	刘现彬,et al."兰州九州台黄土磁性特征及其古气候意义研究".第四纪研究 32.4(2012):761-770.