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The Paleo-Environmental Significance of Sr and Ca Contained in Acid-Soluble Fraction of Plateau Loess Deposits in Xining Basin
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作者 谭红兵 马海州 +2 位作者 鹿化煜 张西营 魏海珍 《Chinese Journal Of Geochemistry》 EI CAS 2003年第2期156-163,共8页
The Xining Basin, located on northeastern Qinghai-Xizang Plateau, is adjacent to the Qaidam Basin and Gobi-desert. Therefore, thick, integrated deposits of loess or paleo-sol sequence were well developed. As is well k... The Xining Basin, located on northeastern Qinghai-Xizang Plateau, is adjacent to the Qaidam Basin and Gobi-desert. Therefore, thick, integrated deposits of loess or paleo-sol sequence were well developed. As is well known, there is much paleo-environmental information recorded in loess and paleo|sol. So if we deal with paleo-environmental index from different angles, especially from loess geochemistry, some important and detailed paleo-environmental evolutional information will be acquired. Based on this, the authors determined the contents of Sr and Ca contained in acid-soluble fraction from the bottom to the top of the Panzishan section. This section was obtained through making a well about 17 m in depth, including S-1 paleo-sol that was developed during the last interglacial period. According to the results, it is found that variations in contents of Sr and Ca are well correlated with conversion of loess and paleo-sol. In loess deposits, the contents of Sr and Ca are higher than those in paleo-sol deposits. It is known that loess was deposited under cold-dry climate conditions and paleo-sol was developed during warm-humid climate episodes. It is concluded that due to their mobile behaviors, under cold-dry climate conditions, Sr and Ca are stagnant during weak weathering, but under warm-humid climate conditions, Sr and Ca are easily leached and transported in aqueous solution. Therefore, they can be utilized as indicators of climate changes. Moreover, variations in contents of Sr and Ca are more sensitive than susceptibility. The mobile behaviors of Sr and Ca contained in acid-soluble fraction can serve as a new quantitative index to evaluate paleo-environmental changes on the plateau. 展开更多
关键词 黄土沉积物 西宁盆地 地球化学 青海高原 西藏高原 古环境
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Chronology of the Holocene loess-paleosol section and its deposition and pedogenesis on the south of Chinese Loess Plateau 被引量:3
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作者 JIA Yaofeng HUANG Chunchang +1 位作者 PANG Jiangli NIU Junjie 《Journal of Geographical Sciences》 SCIE CSCD 2008年第4期425-442,共18页
Optically stimulated luminescence (OSL) dating for polymlneral fine-grained loess samples, collected in Laoguantai (LGT) section on the south of the Chinese Loess Plateau, was made by application of single-aliquot... Optically stimulated luminescence (OSL) dating for polymlneral fine-grained loess samples, collected in Laoguantai (LGT) section on the south of the Chinese Loess Plateau, was made by application of single-aliquot regenerative-dose (SAR) protocol. A 'Double-SAW procedure in which aliquots are subjected to both infrared (IR) and blue stimulations was used and two sets of equivalent dose (De) determinations were produced and assumed to relate predominantly to feldspathic and quartz fine grain populations respectively, The OSL ages estimated from IRSL signals are smaller than those estimated from [post-IR] OSL signals due to the anomalous fading of feldspar IR signals, based on fading experiment, The young ages of the samples near ground surface may be originated from the post-depositional disturbance by the intensifying humanity's cultivation since 3.0 ka BP in the Guanzhong Basin, south of the Chinese Loess Plateau. Based on OSL dating, as well as field observations and stratigraphic correlation, we determine the chronology of the LGT Ioess-paleosol sequence. In combination with climate proxy records, it is indicated that aeolian loess deposition and pedogenesis underwent polyphase changes during the Holocene, likely to have been driven by shifts in the East Asian monsoon. This suggests that aeolian loess deposition is episodic and highly variable, with contributions from non-aeolian processes such as alluvial deposition found in the area. 展开更多
关键词 Chinese loess Plateau loess deposition and pedogenesis East Asian monsoon Hoiocene
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Discovery of Wolitu Pb-Zn deposit through geochemical prospecting under loess cover in Inner Mongolia, China 被引量:3
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作者 Fan Yang Mu Kong +5 位作者 Huazhong Liu Jinsong Yu Shaoping Yang Zhihong Hao Dehui Zhang Kuang Cen 《Geoscience Frontiers》 SCIE CAS CSCD 2017年第5期951-960,共10页
We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, a... We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, and neighboring the Horqin Sandy Land to the north, had no previous history of Pb-Zn mining or record of Pb-Zn mineralization. Our study identified a large Pb-Zn anomaly with potential zones of mineralization by stream sediment survey. Random rock sampling reveals limonitization at sporadic outcrops in the gullies. The high concentrations of Pb in the residual debris provided guidelines to fix the position for exploratory trench. Oxidized concealed orebodies were identified by trenching.Blind orebodies in veins hosted within the structural zone between slates and marbles of the upper Carboniferous Shizuizi Formation and the Permian granite were discovered by drilling. It is computed that the ore reserve may reach up to 540,000 tones with Pb grade of 1.27% and Zn of 1.9%. This case study is an excellent example for identifying potential polymetallic deposits in loess covered terrains using geochemical exploration. 展开更多
关键词 GEOCHEMICAL exploration loess-covered area PB-ZN deposit Resource reserve Inner Mongolia
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Paleoenvironmental changes recorded by grain size of loess/paleosol sequence from the Chifeng City,Northeastern China since the Last Glacial
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作者 LI Juan BRYE Kristofor R +2 位作者 ZHANG Mengge JIANG Zhuodong WANG Qiubing 《Journal of Mountain Science》 SCIE CSCD 2024年第9期3068-3082,共15页
The accumulation processes of loess in northeastern(NE)China record the varying characteristics of the East Asian Monsoons(EAM)and the evolution of the local environment.In this study,grain size end-member analysis of... The accumulation processes of loess in northeastern(NE)China record the varying characteristics of the East Asian Monsoons(EAM)and the evolution of the local environment.In this study,grain size end-member analysis of the Dajiugang(DJG)section deposited since the Last Glacial in Chifeng City,NE China was used to reveal the dynamic depositional characteristics of loess and environmental evolution of NE China.Results showed that the Chifeng loess comprises three grain size end-members(EM),EM1(7.38μm),EM2(49.4μm)and EM3(90.00μm),indicating the three transport dynamics of dust delivered to the region.The EM1 represents atmospheric dust as the background.The EM2,mainly derived from relatively distant-sources deposition,and EM3,material transported over a short distance,correspond to the intensity of southwesterly winds and the East Asian Winter Monsoon(EAWM),respectively.Results of climate reconstruction,combined with other records,showed that the climate was generally cold and dry with a strong EAWM and a weak East Asian summer monsoon(EASM)during the stadial-period[Marine Isotope Stage(MIS)4 and MIS 2 stage].The climate was predominantly warm and humid,with weak EAWM and surface winds and strong EASM in interstadial-period(MIS 3 and MIS 1 stage).Comparisons between indicators,e.g.,EM3,the LR04 benthicδ18O stack and summer insolation at 65°N suggest that the strong EAWM is induced by increasing the Northern Hemisphere ice volume and reduced summer solar radiation. 展开更多
关键词 loess deposit Grain size end-member Northeastern China Environmental change The Last Glacial
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2023年积石山6.2级地震诱发大规模黄土液化流滑的特征与启示 被引量:7
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作者 王兰民 许世阳 +8 位作者 王平 王睿 车爱兰 周燕国 吴志坚 王谦 蒲小武 柴少峰 马星宇 《岩土工程学报》 EI CAS CSCD 北大核心 2024年第2期235-243,共9页
2023年12月18日23时59分,甘肃省积石山县发生了6.2级地震,震中位于北纬35.7°,东经102.79°,震源深度10 km。本次地震在距震中约20 km的青海省海东市民和县永川乡金田村和草滩村二级阶地黄土台塬地貌下引发了长2.5 km的大规模... 2023年12月18日23时59分,甘肃省积石山县发生了6.2级地震,震中位于北纬35.7°,东经102.79°,震源深度10 km。本次地震在距震中约20 km的青海省海东市民和县永川乡金田村和草滩村二级阶地黄土台塬地貌下引发了长2.5 km的大规模液化流滑灾害,引起了国内外的高度关注。笔者在震后立即对该液化流滑灾害和地震动特征进行了现场联合调查,基于现场考察、无人机现场勘测、钻孔勘探、电法探测、参考历史同类灾害的前期研究成果等手段,初步查明了液化流滑的特征与机理。结果表明,该液化流滑是由于地震触发11 m深度以下地下水饱和的黄土层大面积液化,上覆土体随液化土体沿液化层带顺着2°~3.5°的缓斜坡方向流滑进入冲沟,然后,沿坡度为1.5°~5°的冲沟向下游继续流滑。在流滑过程中,液化土体中喷涌出的大量水与上覆土体中高含水率表层土中的水不断与流滑土体搅合揉搓使得流滑混合体在到达冲沟中下部的拦洪坝之前,已经演化为泥流。在遇到拦洪坝受阻漫溢到左右两岸的同时,泥流转而也进入了左侧另一条相邻冲沟一定距离,最终拦洪坝溃坝,泥流继续下泄到了金田村和草滩村,造成两村51户房屋被埋或冲毁,20余人死亡,泥流最终停止于两村下游约317 m处。并在结论中得到了评估与减轻此类灾害风险的启示。 展开更多
关键词 液化 流滑 黄土地层 地震动 放大效应
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Effects of nitrogen addition on the soil detachment in the typical grasslands of the Loess Plateau
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作者 LI Pan-pan WANG Bing +1 位作者 YANG Yan-fen LIU Guo-bin 《Journal of Mountain Science》 SCIE CSCD 2022年第12期3503-3516,共14页
Nitrogen deposition will alleviate the nitrogen limitation in terrestrial ecosystems and greatly affect vegetation growth,thereby soil erosion.It is important to clarify the effects of nitrogen addition to the plant r... Nitrogen deposition will alleviate the nitrogen limitation in terrestrial ecosystems and greatly affect vegetation growth,thereby soil erosion.It is important to clarify the effects of nitrogen addition to the plant roots and soil properties on the soil erosion process.A nitrogen addition experiment was conducted in the grassland dominated by Bothriochloa ischaemum(Linn.)Keng(BI),which has received 0,2.5,5,and 10 g N m^(-2) yr^(-1)(N_(0),N_(2.5),N_(5)and N_(10),respectively)for three consecutive years.Then,a total of 150 undisturbed soil samples were collected(including bare soil control)and subjected to flowing water to test their soil detachment capacities under six shear stress levels(10.2 Pa to 29.9 Pa).Three-year nitrogen addition increased the soil bulk density,soil cohesion and nitrate nitrogen while decreasing the saturated hydraulic conductivity,soil water-stable aggregates,soil organic carbon,total nitrogen and ammonium nitrogen.The root mass density and root diameter decreased with nitrogen addition.And the root length,surface area and volume density of the N_(0) and N_(5) treatments were larger than those of the other treatments,while the plant roots were significantly inhibited by N_(10).Additionally,the soil detachment capacity(D_(c))and rill erodibility(K_(r))of the N_(0) and N_(5) treatments were significantly less than those of the N_(2.5) and N_(10)treatments,of which the Dc(0.020 kg m^(-2) s^(-1))of the N_(0) treatment was 69.0%,24.3%and 66.8%less than that of the N_(2.5),N_(5) and N_(10) treatments,respectively.The Kr of the N_(0) treatment was 0.0012 s m^(-1),which was 72.1%,25.0%and 70.0%less than that of the others.This study implies that an increase in nitrogen addition likely exacerbates soil erosion in the early(approximately 2.5 g N m^(-2) yr^(-1))and late phases(more than 10 g N m^(-2) yr^(-1)).However,when the nitrogen addition rate is approximately 5 g m^(-2) yr^(-1),soil erosion may be inhibited because of the responses of the plant roots and soil to nitrogen addition. 展开更多
关键词 Nitrogen deposition Root traits Soil properties Soil detachment GRASSLAND loess Plateau
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Grain size characteristics and genesis of the Muxing loess in the Muling- Xingkai Plain,Northeast China
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作者 Zhong-shuang Cheng Chen Su +3 位作者 Zhao-xian Zheng Zhuang Li Li-kang Wang En-bao Wang 《Journal of Groundwater Science and Engineering》 2021年第2期152-160,共9页
Thick loess is deposited on the platform in the piedmont zone of Muling-Xingkai Plain(Muxing Plain),but the genesis of the Muxing loess is still unclear.The aims of this study are to analyze the grain size characteris... Thick loess is deposited on the platform in the piedmont zone of Muling-Xingkai Plain(Muxing Plain),but the genesis of the Muxing loess is still unclear.The aims of this study are to analyze the grain size characteristics of Muxing loess collected from the cores of a typical borehole(ZK1)in the piedmont zone of Muxing Plain,and to verify its genesis.The Muxing loess is mainly composed of the particles with diameter less than 50μm,with an average content of 92.48%.The coarse silt particles with diameter of 10-50μm are the basic composition of aeolian sediments,and their average content is 44.34% for the Muxing loess,which is the mode class among the particles with different diameters.The grain size parameters and frequency curves are similar to those of the typical aeolian sediments.The distribution characteristic of the Muxing loess in the C-M scatter diagram is consistent with that of the Xi Feng loess.In addition,the discriminant analysis shows the Muxing loess mostly consists of aeolian sediments.Therefore,it can be concluded that the Muxing loess mainly resulted from aeolian deposition based on the grain size characteristics.Muxing Plain is dominated by the monsoon climate,and the wind-blown dusts are gradually deposited after being transported over long distances. 展开更多
关键词 Muxing Plain loess Grain size Characteristics Aeolian deposition
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XRF和ICP-MS测定风成沉积铜镍锌等9种重金属元素的对比分析
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作者 曾方明 詹涛 陈陵康 《盐湖研究》 CAS CSCD 2024年第2期9-16,共8页
风成沉积的重金属元素对生态环境变化具有指示意义,因此快速、准确地测定其含量显得特别重要。目前,主要通过XRF(X射线荧光光谱)和ICP-MS(电感耦合等离子体质谱)方法测定重金属元素的含量。文章对四个风成沉积剖面(黄土高原西峰剖面,青... 风成沉积的重金属元素对生态环境变化具有指示意义,因此快速、准确地测定其含量显得特别重要。目前,主要通过XRF(X射线荧光光谱)和ICP-MS(电感耦合等离子体质谱)方法测定重金属元素的含量。文章对四个风成沉积剖面(黄土高原西峰剖面,青藏高原东北部种羊场剖面、泉吉河剖面、依毛剖面)247件样品进行了XRF和ICP-MS分析,并对其中9种重金属元素的含量进行了初步对比分析。结果表明:1. Cu、Ni、Zn的XRF测试结果和ICP-MS测试结果高度一致(Pearson相关系数r大于0.84)。2. Co、Pb的XRF测试结果和ICP-MS测试结果在大多数剖面中具有较好的一致性,但在个别剖面中的一致性较差。3.在种羊场和泉吉河剖面中,Th的XRF测试结果比ICP-MS的测试结果略低。两种方法测得的As的含量在四个剖面中随深度的变化趋势高度一致;As的XRF测试结果明显比ICP-MS的测试结果低,差值可达11.5μg/g(相对于XRF法测定值的变化幅度达214%)。4. Cr和T的XRF测试结果高于ICP-MS的测试结果,两种方法测得的Cr含量的差值达40μg/g。尽管ICP-MS法具有比XRF法更高的精度,但对于Cu、Ni、Zn,采用高效廉价的XRF法能得到与ICP-MS法相媲美的测试结果。5.西峰、种羊场剖面采用XRF法测得的Cu、Ni、Zn、As含量与磁化率呈现相似的变化,表明这些元素亦可指示风成沉积记录的气候环境变化。 展开更多
关键词 重金属元素 XRF 风成沉积 黄土高原 青藏高原
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压实黄土压缩变形规律及其数学模型
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作者 亢佳玉 王丽琴 +3 位作者 巩江峰 王新东 程芳卉 徐冲 《西安科技大学学报》 CAS 北大核心 2024年第5期942-952,共11页
黄土高填方是岩土工程领域的热点问题,其地基稳定与沉降也是填方地区的重点关注问题,而要准确地预测填方区的地基总沉降量或工后沉降量数据,就需要对压实黄土的压缩变形规律进行研究。通过大量室内侧限压缩试验研究高填方地区压实黄土... 黄土高填方是岩土工程领域的热点问题,其地基稳定与沉降也是填方地区的重点关注问题,而要准确地预测填方区的地基总沉降量或工后沉降量数据,就需要对压实黄土的压缩变形规律进行研究。通过大量室内侧限压缩试验研究高填方地区压实黄土的压缩变形规律,分析不同地区压实黄土在不同条件下的应力-应变曲线,讨论其压缩特性及变化规律,通过复合幂-指数(CPE)模型建立了描述压实黄土侧限条件下应力-应变曲线的表达方法。结果表明:侧限条件下,压实黄土的应变随竖向应力的逐级增加而增加;不同场地、沉积时代压实黄土的压缩变形规律基本相似,施加相同竖向应力时,应变随含水率的降低而减小,随压实度的增加而减小;随着压实度的增加,试样抵抗变形的能力越来越强;而随着含水率的增加,土体抵抗变形的能力被削弱。考虑到含水率与压实度,将不同沉积时代下CPE模型参数进行定量描述,压实黄土在侧限条件下的应力-应变曲线数学模型在吕梁Q3黄土中的应用,说明了该模型的准确性与合理性,为研究压实黄土的压缩变形提供了新思路。 展开更多
关键词 压实黄土 侧限压缩试验 变形规律 数学模型 沉积时代
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Changes in grain-size and sedimentation rate of the Neogene Red Clay deposits along the Chinese Loess Plateau and implications for the palaeowind system 被引量:13
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作者 WEN Lingjuan LU Huayu QIANG Xiaoke 《Science China Earth Sciences》 SCIE EI CAS 2005年第9期1452-1462,共11页
The wind system responsible for transporting dust onto the Chinese Loess Plateau during the late Miocene and Pliocene is still unknown and recent investigations highlight many controversies. This report aims to invest... The wind system responsible for transporting dust onto the Chinese Loess Plateau during the late Miocene and Pliocene is still unknown and recent investigations highlight many controversies. This report aims to investigate spatiotemporal changes in grain-size and sedi- mentation rate of the Neogene Red Clay deposits in north China and to explore palaeoclimatic changes during the late Miocene and Pliocene, in particular the palaeowind system that trans- ported dust. Samples were collected from eight Red Clay sections on the Loess Plateau. Meas- urement and analysis show that there is a clear southward decrease in the mean grain-size index and in the coarse particle fraction (>20 μm). At Jiaxian site on the northern Loess Plateau, the average mean grain-size is around 20 μm, while at Lantian site in the south, the mean is around 9 μm. The coarse particle fraction >20 μm makes up 24.4% and 5.6%, at the two sites respec- tively. This distinct diversity of grain-size in the aeolian Red Clay deposit between the north and south indicate that the palaeodust was transported mainly by northerly low-level winds. The grain-size variations in the Red Clay deposits can also be divided into three stages (the lower, the middle and the upper interval): grain-size of the lower stage is significantly coarser than that of the middle stage, but finer than that of the upper stage. As a consequence, the intensity of pa- laeowind and desiccation of the dust source region during the late Miocene and Pliocene can be divided into three stages: 6.2―5.4 Ma, 5.4―3.5 Ma and 3.5―2.6 Ma. Strength of the palaeowind during the middle stage (5.4―3.5 Ma) is weaker than that of the previous and subsequent stages and the intensity of palaeowind during the latest stage (3.5―2.6 Ma) is stronger than that of the early time (6.2―5.4 Ma). Variations in the sedimentation rate of the Red Clay deposit can also be divided into three stages: the earlier, the middle and the later interval. The sedimentation rate of the earlier stage is higher than during the middle stage, but lower than during the later one. This is a clear indicator of changes in the palaeowind intensity and aridity in the dust source region and may be linked with global ice volume changes during the late Miocene and the Pliocene. 展开更多
关键词 Red Clay deposit grain size atmospheric circulation the late MIOCENE and the Pliocene Chinese loess Plateau.
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Climatic instability recorded by the mollusk assemblages from the late glacial loess deposits in China 被引量:5
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作者 Naiqin Wu D. D. Rousseau Dongsheng Liu 《Chinese Science Bulletin》 SCIE EI CAS 1999年第13期1238-1242,共5页
The loess-paleosol sequence in China records abundant and valuable information on the global and regional climate changes. Biological record from the loess sequence is the most direct evidence on variation in pattern ... The loess-paleosol sequence in China records abundant and valuable information on the global and regional climate changes. Biological record from the loess sequence is the most direct evidence on variation in pattern of paleo-atmospheric circulation and changes in winter and summer monsoon. A new record of climatic instability, which occurred in the Loess Plateau during the late glacial period, is presented. Through the study of terrestrial mollusks from three loess sequences, the authors intend to characterize the biological response process to rapid climate change and to learn the mechanisms driving the instable climate changes and the possible linkage in different regions. The result shows the striking consistent variability in the ratio records of three mollusk sequences of the late glacial, indicating apparent rapid climate fluctuations. Correlation of our three mollusk records with the oxygen isotopic records from Greenland ice cores and foraminiferal records from the Northeast Pacific Ocean 展开更多
关键词 MOLLUSK ASSEMBLAGES loess deposits late GLACIAL period.
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Application of ^(137)Cs fingerprinting technique to interpreting sediment production records from reservoir deposits in a small catchment of the Hilly Loess Plateau,China 被引量:14
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作者 ZHANG XinBao WEN ZhongMing +2 位作者 FENG MingYi YANG QinKe ZHENG JinJun 《Science China Earth Sciences》 SCIE EI CAS 2007年第2期254-260,共7页
According to variations of 137Cs and clay contents, 44 flood couplets were identified in a profile of res- ervoir deposit with a vertical length of 28.12 m in the Yuntaishan Gully. Couplet 27 at the middle of the prof... According to variations of 137Cs and clay contents, 44 flood couplets were identified in a profile of res- ervoir deposit with a vertical length of 28.12 m in the Yuntaishan Gully. Couplet 27 at the middle of the profile had the highest average 137Cs content of 12.65 Bq·kg?1, which indicated the 1963s' deposits, then 137Cs content decreased both downward and upward in the profile. The second top and bottom couplets had average 137Cs contents of 2.15 Bq·kg?1 and 0.92 Bq·kg?1, respectively. By integrated analysis of reservoir construction and management history, variations of 137Cs contents over the profile, sediment yields of flood couplets and rainfall data during the period of 1958-1970, individual storms related to the flood couplets were identified. 44 floods with a total sediment yield of 2.36×104 m3 occurred and flood events in a year varied between 1 and 10 times during the period of 1960-1970. 7-10 flood events occurred during the wet period of 1961-1964 with very wet autumn, while only 1-2 events during the dry period of 1965-1969. Average annual specific sediment yield was 1.29×104 t·km?2·a?1 for the Yuntaishan Gully during the period of 1960-1970, which was slightly higher than 1.11 ×104 t·km?2·a?1 for the Upper Yanhe River Basin above the Ganguyi Hydrological Station and slightly lower than 1.40 ×104 t·km?2·a?1 for the nearby Zhifang Gully during the same period. Annual specific sediment yields for the Yuntaishan Gully were correlated to the wet season's rainfalls well. 展开更多
关键词 Hilly loess Plateau small catchment reservoir deposit ^(137)Cs fingerprinting technique sediment yield
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Identification of aeolian loess deposits on the Indo-Gangetic Plain(India)and their significance 被引量:2
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作者 LIU XiuMing MA MingMing +1 位作者 WU HaiBin ZHOU ZiBo 《Science China Earth Sciences》 SCIE EI CAS CSCD 2017年第3期428-437,共10页
Aeolian loess deposits contain abundant information about the evolution of the paleoenvironment.For example,paleoclimate changes recorded in Chinese loess area obtained significant achievement in the past few decades.... Aeolian loess deposits contain abundant information about the evolution of the paleoenvironment.For example,paleoclimate changes recorded in Chinese loess area obtained significant achievement in the past few decades.Compared to Chinese loess,research on Indian loess is lacking.Currently,most studies focus on the Kashmir area located in the southern Himalayas,and studies on other areas are rare.However,field observations demonstrate that the sediments around the New Delhi-Agra-Jaipur Plain are similar to Chinese loess-paleosol sequences.For example,the boundary between two strata is transitional and without horizontal bedding.Moreover,obvious pedogenic horizons developed among sediment sequences,probably indicating unrecognised aeolian deposits in the Indo-Gangetic Plain(IGP).To confirm this,pilot samples were obtained from the IGP and detailed indoor measurements conducted.The results indicate that the distribution patterns of particle size and rare earth elements(REE) of the pilot samples are similar to Chinese loess.Furthermore,the scanning electronic microscopy(SEM) images of pilot samples show obvious conchoidal fractures,dash-shaped concavities,and abundant small pits that usually form through mechanical impact.These are typical characteristics of aeolian particles.In addition,environmental and rock magnetic measurements indicate that the dominant magnetic minerals in the pilot samples are magnetite and maghemite,and that they likely contain small amounts of hematite.Furthermore,conventional magnetic parameters are comparable with Chinese loess.Based on this,aeolian loess deposits are widely distributed in the IGP,which may have promoted the development of Indian farming and contributed towards the prosperity of ancient Indian civilisation.This study also provides a new and valuable record for the research on paleoclimate changes in the study area in the future. 展开更多
关键词 Indo-Gangetic Plain loess deposits Particle size SEM REE Environmental magnetism Ancient civilisation
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陕北子洲县典型淤地坝淤积过程和降雨关系的研究 被引量:29
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作者 魏霞 李占斌 +2 位作者 沈冰 李勋贵 鲁克新 《农业工程学报》 EI CAS CSCD 北大核心 2006年第9期80-84,共5页
淤地坝作为黄土丘陵沟壑区水土流失治理的重要工程措施之一,其坝系优化布局、相对稳定性及坝地效益等受到广泛关注,但对其淤积过程研究甚少。该文通过对黄土高原淤地坝进行调查,典型坝淤积过程剖面的观测及取样分析,结合库容曲线和每个... 淤地坝作为黄土丘陵沟壑区水土流失治理的重要工程措施之一,其坝系优化布局、相对稳定性及坝地效益等受到广泛关注,但对其淤积过程研究甚少。该文通过对黄土高原淤地坝进行调查,典型坝淤积过程剖面的观测及取样分析,结合库容曲线和每个淤积层的淤积厚度求出分层淤积量。根据暴雨产沙过程原理及淤积过程降雨资料,反演淤地坝各淤积层所对应的次侵蚀性降雨,建立层淤积量与相应次侵蚀性降雨指标的相关方程。研究结果表明:坝地淤积物中层淤积量和次侵蚀性降雨的降雨侵蚀力呈幂函数关系,层淤积量和次侵蚀性降雨的最大30 m in降雨强度呈指数函数关系,经检验结果良好。 展开更多
关键词 黄土高原 淤地坝 淤积过程 淤积过程反演
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西宁地区湟水阶地的形成与发育研究 被引量:31
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作者 曾永年 马海洲 +1 位作者 李珍 李玲琴 《地理科学》 CSSCI CSCD 北大核心 1995年第3期253-258,共6页
西宁地区是湟水谷地河流阶地发育最典型的区域之一.根据湟水6级阶地上黄土的沉积年代,推算出湟水及其各级阶地在西宁地区的形成年代.青藏高原间歇性的构造抬升和全球气候演比控制着湟水阶地的形成与发育过程.
关键词 黄土沉积 古土壤 湟水阶地 西宁
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天水-秦安一带中新世黄土堆积区沉积-地貌演化 被引量:24
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作者 袁宝印 郭正堂 +13 位作者 郝青振 彭淑贞 乔彦松 吴海斌 肖国桥 葛俊逸 孙斌 周鑫 尹秋珍 梁美艳 秦利 刘恋 姚政权 刘东生 《第四纪研究》 CAS CSCD 北大核心 2007年第2期161-171,共11页
前人的构造地质学研究,将天水-秦安一带的中新世黄土分布区划归两个不同的构造单元。文章基于野外调查和已有年代地层学工作,结合前人成果,对该区新生代沉积-地貌演化历史进行研究,并划分为以下主要阶段:1)古近纪初南部秦岭山地的剥蚀,... 前人的构造地质学研究,将天水-秦安一带的中新世黄土分布区划归两个不同的构造单元。文章基于野外调查和已有年代地层学工作,结合前人成果,对该区新生代沉积-地貌演化历史进行研究,并划分为以下主要阶段:1)古近纪初南部秦岭山地的剥蚀,使本区在原有基岩准平原地形的基础上,形成以冲洪积平原为主的地形。古近纪末-新近纪初的构造活动使冲洪积平原解体,在秦安地区形成基岩台地与沉陷盆地相间、天水-西和地区形成拉分盆地与隆起山地交错的地貌景观,这些高地为中新世黄土堆积提供了地形基础。2)中新世从22Ma到11Ma,基岩台地和相对平缓的高地上堆积典型黄土-古土壤序列,盆地内则主要发育次生黄土等洼地沉积,表明研究区类似于今天的黄土高原。3)中新世晚期约11Ma起发生的一次侵蚀事件,使研究区的一些小盆地内发育河流相和间歇性浅湖相沉积,秦安一带的黄土堆积也遭到侵蚀,形成的洼地内发育黄土状土或洼地静水沉积,其中包含较多哺乳动物化石,而大范围的相对平坦高地上一直继续发育黄土-古土壤序列。这次侵蚀对本区内甘肃群的沉积多样性有重要贡献,但一直没有深水湖泊发育的条件。4)发生于3.5Ma以后的另一次重大侵蚀,奠定了该区今天狭窄长墚地形的基础,是第四纪黄土堆积在本区保存较差的主要原因。 展开更多
关键词 地貌演化 黄土堆积 中新世 秦安
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洛川黄土记录的最近2500ka东亚冬夏季风变化周期 被引量:39
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作者 鹿化煜 安芷生 +2 位作者 刘洪滨 杨文峰 张福青 《地质论评》 CAS CSCD 北大核心 1998年第5期553-558,共6页
对厚约140m的陕西洛川坡头村黄土剖面进行间距3~10cm的系统采样,测量了全部样品的磁化率和粒度。选择>30μm颗粒百分含量和磁化率分别作为东亚冬、夏季风强度变化的替代性指标,以新建立的时间标尺为基础,分析了最近2500ka以来东亚... 对厚约140m的陕西洛川坡头村黄土剖面进行间距3~10cm的系统采样,测量了全部样品的磁化率和粒度。选择>30μm颗粒百分含量和磁化率分别作为东亚冬、夏季风强度变化的替代性指标,以新建立的时间标尺为基础,分析了最近2500ka以来东亚季风变化的周期特征。结果表明,第四纪东亚冬、夏季风变化时间序列包含有100ka、41ka和23ka地球运动轨道要素变化的周期,同时包含有约80ka、56ka和30ka的周期。季风变化周期表现为阶段性演化和在同一阶段冬、夏季风变化周期常常不同的特征。这些结果说明第四纪东亚季风变化既与地球轨道要素变化有关,也与季风系统内其它因素变化有关。 展开更多
关键词 洛川 黄土记录 东亚 冬夏季风 季风 变化周期
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甘肃秦安糜子湾剖面中新世风尘堆积的磁性地层学研究 被引量:53
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作者 刘进峰 郭正堂 +4 位作者 郝青振 彭淑贞 乔彦松 孙斌 葛俊逸 《第四纪研究》 CAS CSCD 北大核心 2005年第4期503-509,共7页
文章对西部黄土高原糜子湾黄土-古土壤剖面进行了磁性地层学研究。该剖面厚度为164.4m,记录了15个正磁极性段和15个负磁极性段,可与标准极性表中从C5r.3r到C5En之间的极性带对比。根据极性界限用平均沉积速率外推,得到该剖面顶界年龄为... 文章对西部黄土高原糜子湾黄土-古土壤剖面进行了磁性地层学研究。该剖面厚度为164.4m,记录了15个正磁极性段和15个负磁极性段,可与标准极性表中从C5r.3r到C5En之间的极性带对比。根据极性界限用平均沉积速率外推,得到该剖面顶界年龄为约11.6MaB.P.,底界年龄为约18.5MaB.P.。糜子湾剖面位于已发表的QAⅠ中新世黄土剖面以东约30km,两剖面相同时代的地层在岩性地层结构和磁化率曲线波动上具有高度的一致性,表明中新世黄土-古土壤序列与第四纪黄土-古土壤序列一样,地层在空间上有很好的可对比性。文章的结果为从空间角度研究中新世环境变化行为提供了新剖面的年代地层框架。 展开更多
关键词 黄土-古土壤序列 磁性地层 风尘堆积古环境 中新世
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新疆伊犁地区黄土的粒度特征与物质来源 被引量:31
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作者 叶玮 靳鹤龄 +1 位作者 赵兴有 陈险峰 《干旱区地理》 CSCD 北大核心 1998年第4期1-8,共8页
伊犁地区是新疆重要的黄土分布区之一。黄土的粒度分析结果表明,与东部季风区黄土类似,黄土组成中以粉砂占优势,但伊犁地区的黄土却以砂含量低,细粉砂和粘粒含量高而显著区别于黄土高原的典型黄土沉积和新疆其它地区的黄土,反映西... 伊犁地区是新疆重要的黄土分布区之一。黄土的粒度分析结果表明,与东部季风区黄土类似,黄土组成中以粉砂占优势,但伊犁地区的黄土却以砂含量低,细粉砂和粘粒含量高而显著区别于黄土高原的典型黄土沉积和新疆其它地区的黄土,反映西风的远源输送在该区域黄土形成过程中扮演着重要角色,粉尘来自西部荒漠。 展开更多
关键词 伊犁地区 黄土 沉积特征 粒度特征 物质来源
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新疆伊犁盆地黄土古气候记录与Heinrich事件对比分析 被引量:9
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作者 张文翔 史正涛 +2 位作者 刘勇 苏怀 牛洁 《冰川冻土》 CSCD 北大核心 2015年第4期973-979,共7页
伊犁盆地作为中国黄土高原与欧洲黄土区的过渡区域,其第四纪古气候研究对于揭示全球气候驱动及耦合机制具有重要的意义.通过对伊犁盆地塔勒德晚更新世黄土-古土壤剖面粒度、低频磁化率及地球化学元素分析,探讨了西风区黄土-古土壤序列... 伊犁盆地作为中国黄土高原与欧洲黄土区的过渡区域,其第四纪古气候研究对于揭示全球气候驱动及耦合机制具有重要的意义.通过对伊犁盆地塔勒德晚更新世黄土-古土壤剖面粒度、低频磁化率及地球化学元素分析,探讨了西风区黄土-古土壤序列中古气候指标变化特征及记录的全球气候突变事件.结果表明:古土壤层中粒径<10μm颗粒物含量明显高于黄土层,与之相反的是古土壤层中的低频磁化率、Zr/Rb值和元素Ti含量均小于黄土层,且元素Ti含量与Zr/Rb间具有较高的相关性.黄土-古土壤剖面中古气候代用指标清晰的记录了6次Heinrich(H)事件及Younger Drays(YD)事件,但YD事件、H1、H2、H5和H6事件变幅较H3和H4事件显著,古气候指标与格陵兰冰芯δ18O、季风区李家塬粒度和洛川、西峰及环县Zr/Rb值均具有较好的一致性,所记录的气候事件较李家塬、洛川、西峰更为显著.结合已有研究说明,Heinrich和D-O旋回等气候事件是由西风区向季风区传递的,MIS3阶段温度的升高和常年受西风的影响是造成塔勒德气候环境变化特征的主要控制因素. 展开更多
关键词 黄土沉积 Henrich事件 伊犁盆地 西风区 黄土高原
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