干旱区生态环境知识资源中心(Arid): 泥河湾盆地大长梁剖面河湖相沉积序列的细腰磁滞回线性质及其环境意义

Arid

	泥河湾盆地大长梁剖面河湖相沉积序列的细腰磁滞回线性质及其环境意义
其他题名	WASP-WAISTED HYSTERESIS LOOPS FROM THE DACHANGLIANG FLUVIO-LACUSTRINE SEQUENCE IN THE NIHEWAN BASIN, NORTH CHINA AND ITS PALEOCLIMATIC SIGNIFICANCE
	敖红; 刘彩彩; 邓成龙
来源期刊	第四纪研究
ISSN	1001-7410
出版年	2007
卷号	27 期号:6 页码:1072-1080
中文摘要	对华北泥河湾盆地大长梁剖面更新世河湖相沉积序列进行的多参数岩石磁学研究表明磁铁矿和赤铁矿是大长梁剖面最主要的磁性矿物.磁铁矿的粒度主要为准单畴和多畴,主要来自盆地周围侵蚀的碎屑矿物;赤铁矿主要为风成成因,来源于中国西北部的黄土高原或沙漠地区的化学风化作用产物;某些沉积层中还含有主要由碎屑成因的粗颗粒磁铁矿经低温氧化形成的磁赤铁矿,该过程可能与泥河湾古湖的氧化环境演化密切相关.大长梁剖面的磁滞回线大多具有细腰特征,细腰的明显程度主要由样品中磁铁矿和赤铁矿的相对贡献控制.因此,细腰磁滞回线可以用来衡量泥河湾河湖相沉积物中赤铁矿的相对含量,并进而在一定程度上指示亚洲内陆干旱/半干旱地区化学风化作用的强弱以及相对温湿或冷干的气候环境变化.
英文摘要	The fluvio-lacustrine sequence of the Pleistocene age in the Nihewan Basin, North China, contains high-resolution archives of early human evolution and paleoenvironment changes. In this study, a multi-parameter investigation such as the high temperature magnetic susceptibility (X-T curves)and magnetization(MS-T curves), IRM acquisition and DC field demagnetization of IRM1.5T(IRM acquires at an applied field of 1.5T), first order reversal curve(FORC)diagrams, magnetic hysteresis loops, and low temperature demagnetization of saturation isothermal remanent magnetization(SIRM)was carried on the samples collected from the Dachangliang section located at the east margin of the basin. 196 samples from the depth interval of 11～73m with a spacing of 20～40cm were collected for the present investigation. Results show that magnetite is the major magnetic materials and magnetic carrier of the characteristic remanent magnetization. Magnetite is dominated by pseudo-single-domain(PSD)or multidomain(MD)grains, mainly the detrital input from the catchment regolith. Hematite, another important magnetic carrier of the characteristic remanent magnetization, is not well expressed in the X-T curves due to its weak susceptibility. However, the combined characters of MS-T curves, IRM acquisition and DC field demagnetization of IRM1.5T, the hysteresis loops and the FORC diagrams well demonstrate the presence of hematite. Hematite is dominated by the eolian hematite grains formed by chemical weathering in the Loess Plateau region or the deserts in Northwest China. Some X-T curves show a susceptibility hump at about 300℃, which suggests that maghemite may also exist in some samples. Our analysis shows that maghemite may mainly come from low temperature oxidation of coarse detrital magnetite grains. This low temperature oxidation process may relate to the oxidation/reduction condition in the Nihewan paleolake. Most of the magnetic hysteresis loops from the Dachangliang section show a wasp-waisted behavior, and the degree of wasp-waistedness is mainly controlled by the relative content of magnetite and hematite in the samples. Therefore, to some extent, the wasp-waisted hysteresis loops can be used to assess the relative content of hematite in the samples, which can be further used to retrieve the degree of chemical weathering and relatively warm/humid or cold/dry paleoclimate in the arid/semiarid areas of Asian interior. Our present study also demonstrates that the rock magnetic analyses can suggest some climatic significance, which may contribute to a better understanding of early human evolution and paleoenvironment changes at the high-latitude Nihewan Basin during the Early Pleistocene.
中文关键词	泥河湾盆地 ; 岩石磁学 ; 环境磁学 ; 细腰磁滞回线
英文关键词	Nihewan Basin rock magnetism environmental magnetism wasp-waisted hysteresis loop
类型	Article
语种	中文
国家	中国
收录类别	CSCD
WOS类目	Geology
WOS研究方向	Geology
CSCD记录号	CSCD:3003733
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/220837
作者单位	敖红, 中国科学院地质与地球物理研究所, 岩石圈演化国家重点实验室, 北京 100029, 中国.; 刘彩彩, 中国科学院地质与地球物理研究所, 岩石圈演化国家重点实验室, 北京 100029, 中国.; 邓成龙, 中国科学院地质与地球物理研究所, 岩石圈演化国家重点实验室, 北京 100029, 中国.
推荐引用方式 GB/T 7714	敖红,刘彩彩,邓成龙. 泥河湾盆地大长梁剖面河湖相沉积序列的细腰磁滞回线性质及其环境意义[J],2007,27(6):1072-1080.
APA	敖红,刘彩彩,&邓成龙.(2007).泥河湾盆地大长梁剖面河湖相沉积序列的细腰磁滞回线性质及其环境意义.第四纪研究,27(6),1072-1080.
MLA	敖红,et al."泥河湾盆地大长梁剖面河湖相沉积序列的细腰磁滞回线性质及其环境意义".第四纪研究 27.6(2007):1072-1080.