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Progress of loess research in china

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Journal of Geographical sciences 2004年第S1期14卷 59-63页

作者： ZHAO Jingbo1,2. HUAnG Chunchang1(1. Department of Geography, Shaanxi normal University, xi'an 710062. china 2. state {2. laboratory of loess and quaternary, institute of earth environment, CAS, xi'an 710075, china) Department of Geography Shaanxi Normal UniversityXi'an 710062China state key{2. of loess and quaternary Institute of Earth EnvironmentCASXi'an 710075China Department of Geography Shaanxi Normal UniversityXi'an 710062China

Progress in chinese loess research made in recent 15 years was introduced in this paper, including mainly distribution and paleo{2. significance of chinese loess, new development of loess formation age, red-brown paleosol types and {2.al change, loess-paleosol sequence and climate cycles, monsoon strength change during last interglacial and last glacial periods in the loess Plateau, climate events, and source areas of loess and material.

关键词： chinese loess paleosols loess age monsoon strength climate events material source

Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the {2. loess Plateau since 8.0 Ma B.P.

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Science china earth {2. 2006年第5期49卷 518-530页

作者： XUE xiangxu1,2. ZHAnG Yunxiang1,2.& YUE Leping1,2.1. state key {2. of Continent Dynamics (northwest University), institute of Cenozoic Geology and environment, De- partment of Geology, northwest University, xi’an 710069, china 2. institute of earth environment, state key {2. of loess and quaternary Geology, {12., xi’an 710075, china 1. state key {2. of Continent Dynamics (northwest University) Institute of Cenozoic Geology and Environment Department of Geology Northwest University Xi’an 710069 China 2. institute of earth environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an 710075 China

Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated. A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled. The profile is subdivided into 12.stratigraphic units proceeding from the lower (older) to the upper (younger) one. The character of mammalian assemblages contained in each unit was analyzed and the corresponding pa- leo-climatic {2.s were deduced. The {2.al character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P. up to the Holocene progressed from the hot semiarid and semi-moist, warmer-moist, warm-moister of the Late Miocene. To slightly less warm moist, cool-dry, slight-warmer-moister of the Pliocene; later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the quaternary. Vegetation progressed from the grasslands with sparse woods, wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene; and to sparse grasslands, dry grasslands and tundras of the quaternary. The climate changes in the neogene were of low-amplitute in a generally warm-humid background. Those of the quaternary were of higher am- plitude with a longer phase. Cool or cold dry and slightly warm semiarid and semi-moist climates al- ternated on a generally cool-dry background. The tendency since the start of the quaternary was the change to more northern and western shift in the loess Plateau, with progressively cooler and dryer conditions. The dramatic uplift of the Qinghai-xizang (Tibet) Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the quaternary.

关键词： paleoenvironment, mammalian fossils, eolian red clay-loess sequence, loess Plateau.

The microtine distribution and its environmental significance since the Middle Pleistocene in Zhangping Caves of the Qinling Mountains

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Science china earth {2. 2008年第2期51卷 294-299页

作者： LI Yongxiang1 & XUE xiangXu1,2.1 state key {2. of Continental Dynamics, Department of Geology, northwest University, institute of Cenozoic Geology and environment, xi’an 710069, china 2.institute of earth environment, state key {2. of loess and quaternary Geology, {12., xi’an 710075, china 1. state key {2. of Continental Dynamics Department of Geology Northwest University Institute of Cenozoic Geology and Environment Xi’an 710069 China 2. institute of earth environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an 710075 China

Three microtine species are recovered from the Zhangping Caves of the Qingling Mountains, namely Microtus oeconomus, Caryomys inez and Caryomys eva. They are climate-sensitive ones with different ecological habits, therefore their distribution well corresponds to environmental variations. Statistical comparison of the distribution of fossil microtines and their counterparts nowadays displays that the climate variation of the studied area and its contiguity since the middle Pleistocene are: warm and humid at 493 ka ago, cool and humid at 2.9 ka ago―cold and humid at 2.5 ka ago―cool and humid at 2. ka ago, and warm and dry at present.

关键词： environmental variation since Middle Pleistocene microtine fossils Zhangping Caves of the Qinling Mountains

石膏改良碱化土壤中所发生的化学反应的初步研究

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土壤学报 2004年第3期41卷 484-488页

作者：赵锦慧乌力更红梅车慧正中国科学院地球环境研究所黄土与第四纪地质国家重点实验室内蒙古农业大学生态环境学院呼和浩特010019 内蒙古农业大学生态环境学院

利用石膏改良苏打盐碱化土壤，早在19世纪后期，Hilgad~[1,2.就开始指导农民改造黑碱了。当时他将含有nacl、na_2.O_4的土壤称为白碱，而将含有 na_2.O_3、naHCO_3的土壤称为黑碱，即苏打盐土或碱化盐土，并为石膏改良黑碱建立了两个化... 详细信息

利用石膏改良苏打盐碱化土壤，早在19世纪后期，Hilgad~[1,2.就开始指导农民改造黑碱了。当时他将含有nacl、na_2.O_4的土壤称为白碱，而将含有 na_2.O_3、naHCO_3的土壤称为黑碱，即苏打盐土或碱化盐土，并为石膏改良黑碱建立了两个化学方程式，即。

关键词：盐碱化土壤石膏土壤改良化学反应化学方程式

有关湖泊沉积137Cs深度分布资料解译的探讨

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山地学报 2005年第3期23卷 294-299页

作者：张信宝中国科学院水利部成都山地灾害与环境研究所四川成都610041

讨论了国内有关湖泊沉积137Cs断代资料解译的一些问题。一些高寒地区的湖泊,上世纪60年代主核爆期以后,入湖泥沙的137Cs含量变化不大,因此沉积剖面137Cs浓度达峰值后无明显降低趋势。一些浅水湖泊,由于人类活动扰动湖底表层泥沙,剖面表... 详细信息

讨论了国内有关湖泊沉积137Cs断代资料解译的一些问题。一些高寒地区的湖泊,上世纪60年代主核爆期以后,入湖泥沙的137Cs含量变化不大,因此沉积剖面137Cs浓度达峰值后无明显降低趋势。一些浅水湖泊,由于人类活动扰动湖底表层泥沙,剖面表层泥沙的137Cs浓度比较均一。根据核尘埃沉降监测资料,中国湖泊沉积应存在明显的1963年137Cs蓄积峰,不应存在所谓的1974年137Cs次蓄积峰,可能存在不很明显的1986年次蓄积峰。沉积剖面中137Cs浓度的深度变化,不仅和137Cs大气沉降通量变化有关,也和流域内近几十年来的环境变化有关,1963年以后的137Cs次蓄积峰的确定要慎重。黔中红枫湖沉积物137Cs面积活度高于滇西湖泊,主要是由于石漠化严重的喀斯特山地,裸岩面积大,裸岩坡地几无土壤吸附137Cs尘埃,核爆期间137Cs降尘随降雨径流直接流失进入湖泊比例高的缘故,不是青藏高原的大气污染物散落屏蔽效应的结果。

关键词：湖泊沉积 137Cs 深度分布解译

Magnetic properties of Jiaxian red clay sequences from northern chinese loess Plateau and its paleoclimatic significance

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Science china earth {2. 2005年第8期48卷 1234-1245页

作者： QIAnG xiaoke, An Zhisheng, LI Huamei, CHAnG Hong & SOnG Yougui 1. SKLLQG, institute of earth environment, chinese academy of sciences, xi’an {2., china 2. Guangzhou institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, china 1. chinese academy of sciences SKLLQG Institute of Earth Environment 710075 Xi’an China 2. chinese academy of sciences Guangzhou Institute of Geochemistry 510640 Guangzhou China

Detailed rock magnetism investigation of the Jiaxian red clay sequences indicated that there are common magnetic mineralogy properties in red clay and loess-paleosol sequences from the chinese loess Plateau as well as the marked properties of themselves, magnetic min-erals mainly with magnetite, maghemite, hematite, and possibly limonite/goethite contributing to the magnetic behavior. Meanwhile, it is found that the strong paleosol in red clay sequences has a lower coercivity and higher content of ultra-fine ferrimagnetic grains than that of the weak pa-leosol, which is similar to loess and paleosol in upper Wucheng loess sequences, and indicates that humid conditions and relatively strong pedogenesis play a significant role in the increase of ultra-fine magnetic minerals and transformation of the magnetic minerals. This suggests that, like quaternary loess-paleosols, the change of characteristics of paleoclimatic conditions of the late Tertiary red clay deposits is fluctuant. In addition, the results of magnetic hysteresis properties show that the applied saturated field for samples from the Jiaxian red clay sequences is higher than that of the samples from eastern and southern chinese loess Plateau. It is obviously shown that there exist more hard magnetic minerals and relatively weak biochemical processes in the Jiaxian red clay sequences on northern chinese loess Plateau. We conclude that the paleocli-matic environment is different between northern and eastern/southern chinese loess Plateau, and it should be more arid in northern chinese loess Plateau.

关键词： northern chinese loess Plateau, red clay, magnetic property, paleoclimatic significance.

environmental characteristics of Mid-Holocene recorded by lacustrine sediments from Lake Daihai, north environment sensitive zone,{2.

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Science china earth {2. 2006年第9期49卷 968-981页

作者： SUn Qianli1,2. ZHOU Jie1, SHEn Ji3, CHEn Peng1,2. WU Feng1,2.& xiE xiuping1,2.1. state key Lab of {2. and quaternary Geology, institute of earth environment, chinese academy of sciences, xi’an 710075, china 2. Graduate University of chinese academy of sciences, Beijing 100039, china 3. nanjing institute of Geography and Limnology, chinese academy of sciences, nanjing 2.0008, china 1. state key Lab of {2. and quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 2. Graduate University of chinese academy of sciences Beijing 100039 China 3. nanjing institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China

Climate proxies, such as total organic carbon and nitrogen (TOC, Tn), carbonate content (CaCO3), grain-size and pollen of the sediment core retrieved from enclosed Lake Daihai which lies in the north china environment sensitive zone are analyzed to reconstruct the environment evolution of the area based on high-resolution radiocarbon chronology. The results reveal that the TOC and Tn contents of the sediments correlate well with pollen percentage and pollen flux variations during the Holocene, and both reach their peak values simultaneously at 6.7―3.5 ka BP (calendar age, 7.6―3.6 ka BP). Since 6.7 ka BP, both the CaCO3 and organic matter contents of the core have simultaneous variations, and their high values also occur during 6.7―3.5 ka BP. While during 9.0―6.7 ka BP (calendar age, 10―7.6 ka BP) relatively lower level of organic matter content and pollen flux corre- spond to the higher level of carbonate content. The above relations suggest that during 6.7―3.5 ka BP, the productivity and effective precipitation were greatly improved in the lake drainage area, and this would probably strengthen the hydrodynamic conditions, enhancing organic matter, pollen and carbonate inputs from terrestrial sources. Such processes would account for the enrichment of both organic matter and carbonate in the sediments. While during 9.0―6.7 ka BP, the lower level of or- ganic matter, pollen flux but high carbonate content show depressed productivity and declined vege- tation coverage. The higher carbonate content at this stage would have probably resulted from the higher evaporation ratio of the lake water under relatively drier climate conditions. Therefore, it is in- ferred that during 6.7―3.5 ka BP, the climate was more humid with abundant rainfalls and vegetation was more flourishing in the Lake Daihai area. This can be seen as Holocene Climate Optimum (HCO). As a result, this has evident discrepancies with the traditional notion that the HCO occurs at Early Holocene or early Mid

关键词： Lake Daihai, Mid-Holocene, lacustrine sediments, environmental characteristics.

The new basic theory on quaternary environmental research

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Journal of Geographical sciences 2004年第2期14卷 242-250页

作者： ZHAO Jingbo 1, 2. 3 (1. Department of Geography, Shaanxi normal University, xi’an 710062. china 2. Center for Historical environment and Socio-Economic Development in northwest china, Shaanxi normal University, xi’an 710062. china 3. state key laboratory of loess and quaternary, institute of earth environment, CAS, xi’an 710075, china) Department of Geography Shaanxi Normal University Xi’an China Center for Historical environment and Socio-Economic Development in northwest china Shaanxi Normal University Xi’an China state key {2. of loess and quaternary Institute of Earth Environment CAS Xi’an China

On the basis of extensive survey to the quaternary paleosols, soils and weathering layers in the vast northern china and the {2. Plateau, we found some unusually special phenomena of chemical components such as unsuccessive illuvium, twin illuviums, unusually thick illuvium and multi-illuviums etc. According to the analysis on the content of CaCO 3 and the data of penetrating experiment, a new theory of illuvial depth or removal depth of CaCO 3 in weathering and leaching belt was constructed, which indicates that the time of CaCO 3 removing to the illuvial depth is very short, and the effect of time factor on illuvial depth can be ignored. The theory can be taken as a credible foundation for studying many geological and geographical problems in weathering and leaching belt. When the illuvial depth of CaCO 3 is bigger than the thickness of developing belt of soil or paleosol, it can be determined that the paleosol has turned into weathering crust. When the illuvial depth of CaCO 3 is bigger than the thickness of paleosol, paleosol is leaching moderately acid soil. When two, three layers or unusually thick CaCO 3 illuviums exist in the same weathering section or at the bottom of the same paleosol, there were two or more periods forming paleosol and corresponding climatic stages at that time. On the basis of the equation of relationship between mean annual rainfall (y) and illuvial depth of CaCO 3 (x) (y = 305.5x + 168.5) determined in the paper, mean annual precipitation during the development of paleosol can be calculated.

关键词： new illuvial theory quaternary soils CaCO_3 remove illuvial types illuvial depth

Preliminary reconstruction of the desert and sandy land distributions in china since the last interglacial period

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Science china earth {2. 2004年第z1期47卷 89-100页

作者： CHEn Huizhong, SU Zhizhu, YAnG Ping & DOnG Guangrongkey laboratory of Desert and Desertification, Cold and Arid Regions {2.al and Engineering Research institute, chinese academy of sciences, Lanzhou 730000, china state key laboratory of loess quaternary Geology, institute of earth environment, chinese academy of sciences, xi’an 710075, china institute of loess Plateau, Shanxi University, Taiyuan 030006, china 1. key laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences 730000 Lanzhou China 2. state key {2. of loess quaternary Geology Institute of Earth Environment Chinese Academy of Sciences 710075 Xi’an China 3. institute of loess Plateau Shanxi University 030006 Taiyuan China

The desert and sandy land are the products of arid climate. The spatial distribution of modern deserts and sandy land in china and their relation to climate show following characteristics: arid and hyper-arid desert zones, at isohyet of less than 2.0 mm, are dominated by mobile dunes; semi-arid steppe and arid desert steppe with the precipitation between 2.0?00 mm, are dominated by semi-fixed and fixed sand dunes; the precipitation of sub-humid forest grassland and humid forest zones with scattered fixed sand land is higher than 400 mm. With this as reference, in combination with considerable amount of paleoclimatic data in desert regions and adjacent regions, the distributions of desert and sandy land in china during the last intergla-cial period, the last glacial maximum (LGM), and the Holocene megathermal, were preliminarily reconstructed. The results compared with that of today show that the distribution of desert and sandy land in china was greatly dwindled during last interglacial period, and the mobile dune area was about two-thirds of that of today's, but greatly expanded during LGM. However, the dwindling area of desert and sandy land in the Holocene megathermal was smaller than that in the last interglacial period. The forcing mechanism was mainly related to the changes of East Asian winter and summer monsoon, south-northward swing of the westerlies and the variations of the Qinghai-Tibet Plateau monsoon intensity caused by global climate changes during the cold and warm intervals since the last interglacial period.

关键词： the glacial-interglacial period, desert, sandy land, spatial distribution.