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Science China Earth Sciences 2007年第8期50卷 1218-1224页

作者： ZHOU AiFeng chen fahu QIANG MingRui YANG MeiLin ZHANG JiaWu CAEP Key Laboratory of West China’s Environmental System(Ministry of Education)Lanzhou UniversityLanzhou 730000China

Detailed examination of sedimentary cores retrieved from Sugan Lake in the northern Qaidam Basin of northwest China’s Tibetan Plateau reveal that fine laminated beddings form in the sediments where water depth exceeds 3 m. Seasonal surface sediments trapped at the bottom of the lake suggest that sediments deposited during summer and autumn are mainly light colored monohydrocalcites, while those deposited in winter are dark organic matter, indicating that varve layers form under modern limnological conditions. Continuous varve sediments comprising four types have accumulated in the upper 5.5 m of Core SG03I from the center of the lake. All types exhibit clear seasonality indicative of annual deposition. Varve counts correspondence with 210Pb dates on recent sediments in the upper core suggest the continuous varves of the upper 5.5 m of the core formed in the late Holocene (2670 a BP). The Sugan Lake varve sequence is the first demonstration of annually laminated sediments re-ported in arid western China.

关键词： Sugan Lake varve Tibetan Plateau arid China

A study of the construction times of the ancient cities in Ganjia Basin,Gansu Province,China

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Journal of Geographical Sciences 2020年第9期30卷 1467-1480页

作者： XIA Huan ZHANG Dongju WANG Qiang WU Duo DUAN Yanwu chen fahu Key Laboratory of Western China's Environmental Systems(Ministry of Education) College of Earth Environmental SciencesLanzhou UniversityLanzhou 730000China Key Laboratory of Alpine Ecology Institute of Tibetan Plateau ResearchCASBeijing 100101China Center for Excellence in Tibetan Plateau Earth Sciences CASBeijing 100101China

The Ganjia Basin in Xiahe County,Gansu Province,China,is located on the northeastern edge of the Tibetan Plateau.The area lies in the transitional zone between the Plateau ethnic groups dominated by ancestral Tibetans,and the Central Plains dynasties dominated by ancestral Han in history.The Ganjia Basin is therefore well suited to studying the history of the intermixing of the Han and Tibetan peoples.In this study,we collected samples of organic materials from two ancient cities,Bajiaocheng(BJC) and Sirougucheng(SRGC),in the Ganjia Basin,which were used for radiocarbon dating.Our aims were to determine the construction times and function of the cities,based on the radiocarbon ages,Bayesian age modeling,and the analysis of relevant historical records.The results are used to discuss the role of the Ganjia Basin in the conflicts between and the integration of the two ethnic groups during the historical period.We conclude that BJC was established during 663–732 CE(Common Era);its early occupation history can be divided into an initial establishment phase(670–780 CE) and a phase of regeneration(880–1030 CE).SRGC was probably built at the time of the transition between the Song and Yuan dynasties(~1271 CE).Combining the dating results with an analysis of the architectural styles and historical records,we conclude that BJC was originally built by the Tubo Kingdom as a military stronghold,and its major functions were military,economic and religious,and to support the major eastward expansion of the Tubo.SRGC was most likely a temple-focused city intended to promote Tibetan Buddhism which was a major political and religious leadership for the Tibetans at that time,reflecting changes in the status of different religions in the Ganjia Basin.In addition,the intermixing and blending of the Han and Tibetan groups,reflected by the human activities in the Ganjia Basin,was an important demographic and cultural foundation for the formation of the culturally-diverse but spiritually-united modern Chinese people.

关键词： Ganjia Basin radiocarbon dating Bajiaocheng Sirougucheng ethnic amalgamation Tubo

Extension of drylands in northern China around 250 kaBP linked with the uplift of the southeast margin of Tibetan Plateau

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Chinese Science Bulletin 2002年第20期47卷 1739-1745页

作者： WU Haibin GUO Zhengtang FANG Xiaomin ZHANG Jiawu chen fahu Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Department of Geography Lanzhou UniversityLanzhou 730000China Institute of Earth Environment Chinese Academy of SciencesXi'an 710075China

Study on two loess sections, one located at Wu-wei near the Tengger Desert in northwestern China, another located near Ganzi at the southeast margin of the Tibetan Plateau in southwest China, reveals a coeval drying step occurred at -250 kaBP. It is expressed by the increase in eolian grain-size at Wuwei, and by a drastic extension of C4 plants and a decrease of loess chemical weathering intensity at Ganzi. Examination of the available eolian data indicates that the event has also been clearly documented in the loess sections near the deserts in northern China, and in the eolian records from the North Pacific. On the contrary, the signal is rather weak for the central and southern Loess Plateau regions as well as for Central Asia, where the climates are influenced by the southeast Asian monsoon and the westerlies, respectively. Since the climate at Ganzi is under strong control of the southwest Asian monsoon, we interpret this drying step as a result of decreased influence of the southwest summer

关键词： aridification loess-paleosol sequences organic carbon isotope chemical weathering intensity Tibetan Plateau.

Climatic changes documented by stable isotopes of sedimentary carbonate in Lake Sugan,northeastern Tibetan Plateau of China,since 2 kaBP

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Chinese Science Bulletin 2005年第17期50卷 1930-1939页

作者： QIANG Mingrui chen fahu ZHANG Jiawu GAO Shang-yu ZHOU Aifeng China Center of Desert Research at Beijing Normal University and Key Laboratory of Environmental Changes and Natural Disaster Ministry of Education of China Beijing Normal University Beijing 100875 China Center for Arid Environment and Paleoclimate Research (CAEP) Natiunal Laboratory of Western China's Environmental System Ministry of Education of China Lanzhou University Lanzhou 730000 China

Lake Sugan at the northern edge of the Qaidam Basin was selected as the research object. The temporal se-quence of sedimentary cores retrieved from Lake Sugan since 2 kaBP was reconstructed using the 210Pb, AMS 14C and conventional 14C dating methods. Carbon and oxygen iso-topes of carbonate in the fine-grained lake sediments were analysed. Combined with the changes of δ 18O values of sur-face water and air temperature observation data in the study area, it might be thought that the δ 18O value of the carbon-ate indicates effective moisture, and the changes in δ 13C val-ues are related to annual freeze-up duration of the lake and indirectly indicate air temperature changes in winter half year. From the above, the sequence of climatic changes in the region since 2 kaBP was established. The climatic changes experienced five stages: Warm-dry climate during 0-190 AD; cold-dry climate during 190-580 AD; warm-dry cli-mate during 580-1200 AD (MWP); cold-wet climate during 1200-1880 AD (LIA); cold-dry climate during 1880-1950 AD; and climate warming since 1950s. The air temperature changes in winter half year reflected by carbon isotope since 2 kaBP are in good agreement with the historical literature records and other geologic records, which shows that the climate changes recorded by the stable isotopes from Lake Sugan since 2 kaBP are of universal significance.

关键词：气候变化同位素稳定性碳酸盐沉积作用青藏高原

A 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau,China using tree-ring records

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Chinese Science Bulletin 2013年第10期58卷 1107-1114页

作者： GOU XiaoHua YANG Tao GAO LinLin DENG Yang YANG MeiXue chen fahu Key Laboratory of Western China's Environmental Systems(Ministry of Education) and Research School of Arid Environment and Climate Change Lanzhou University State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

This paper presents a 457-year reconstruction of precipitation in the southeastern Qinghai-Tibet Plateau using tree-ring records.Tree-ring samples were collected from the Hengduan Mountains in the southeastern part of the Qinghai-Tibet Plateau,China.A nearly 500-year chronology was developed using tree-ring width records.Correlation analysis shows moisture is the main factor limiting tree growth in this region.Ring-widths were significantly positively correlated with the Palmer Drought Severity Index(PDSI) and precipitation in many months.The highest correlation coefficient was found between the annual growth of trees and precipitation from the previous September to the current June(0.738).Based on this relationship,we reconstructed the precipitation history from 1509 to 2006.The reconstruction explains 54.4%(Radj2=53.5%,N=49,F=56.12) of the actual precipitation variation during the calibration period(1958-2006).During the reliable period of the reconstruction(1549-2006),some low-frequency climate signals are included,indicating this region has been getting wetter in the last 20 years.The reconstruction documents six apparently dry and five pluvial periods and the 17th century dry period lasted longer than any other.When compared with other recent studies,this study and these earlier reconstructions show a similar trend in the variation of drought and pluvial.Further spatial correlation analysis confirms that the reconstructed precipitation adequately represents the rainfall history of the entire Hengduan Mountain area.The Multi-taper method,a type of spectral analysis,reveals that precipitation in this area had significant(P<0.01) spectral peaks at 3-5 a,60 a and 79-85 a.

关键词：青藏高原东南部降水重建树木年轮中国降水量变化树轮宽度干旱指数相关性分析

Central Asian aridification during the late Eocene to early Miocene inferred from preliminary study of shallow marine-eolian sedimentary rocks from northeastern Tajik Basin

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Science China Earth Sciences 2016年第6期59卷 1242-1257页

作者： WANG Xin Brian KRAATZ Jin MENG Barbara CARRAPA Peter DECELLES Mark CLEMENTZ Sherzod ABDULOV chen fahu Key Laboratory of Western China's Environmental Systems(Ministry of Education) College of Earth and Environmental Sciences Lanzhou UniversityLanzhou 730000China Western University of Health Sciences Pomona 91766USA American Museum of Natural History New York 10024USA Department of Geosciences University of ArizonaTucson 85721USA Department of Geology and Geophysics University of WyomingLaramie 82071USA Institute of Geology Earthquake Engineering and Seismology of the Academy of SciencesTajikistan CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China

The tempo-spatial development of the Cenozoic Asian aridification across the Eocene-Oligocene and its controlling factors are important scientific topics in Earth Sciences, which are pertinent to regional and global tectonic and climatic events. However, sedimentary rocks preserving the record of aridification during this time from central Asia(ACA) are rare. Here we present a preliminary analysis of sedimentary facies of the lower Paleogene in the northeastern Tajik Basin, which reveals that: the lower part of the studied section is dominated by shallow marine deposits of the Paratethys, the middle part is typical of alternations of eolian dune and fluvial deposits, the upper part is represented by eolian loess-sandy loess(L&SL) like facies, and the top exhibits alternations of fluvial-lacustrine and loess like facies. Based on a chronological framework derived from preliminary magnetostratigraphy, published U-Pb dating of a volcanic ash, and regional litho-stratigraphic correlations, we determine that eolian and L&SL facies accumulated in the northeastern Tajik Basin during the Late Eocene and through most of the Oligocene. These sedimentary units indicate that semi-arid to arid environments of ACA had developed at least since the late Eocene. This initial aridification is closely linked to the westward retreat of the Paratethys that was likely driven by a combination of tectonic activity and sea level changes.

关键词：塔吉克盆地晚始新世干旱化沉积岩东北部中亚中新世海风

A 1000-year chironomid-based salinity reconstruction from varved sediments of Sugan Lake,Qaidam Basin,arid Northwest China,and its palaeoclimatic significance

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Chinese Science Bulletin 2009年第20期54卷 3749-3759页

作者： chen JianHui chen fahu ZHANG EnLou BROOKS Stephen J ZHOU AiFeng ZHANG JiaWu MOE Key Laboratory of Western China's Environmental Systems Lanzhou University Lanzhou 730000 China State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China Department of Entomology Natural History Museum London SW7 5BD UK

A 1000-year high-resolution(～10 years) chironomid record from varved sediments of Sugan Lake,Qaidam Basin on the northern Tibetan Plateau,is presented.The chironomid assemblages are mainly composed of the relatively high-saline-water taxa Psectrocladius barbimanus-type and Orthocladius/Cricotopus,and the relatively low-saline-water taxa Procladius and Psectrocladius sordidellus-type.Variations in the chironomid fauna and inferred salinities suggest that over the last millennium,the Sugan Lake catchment has alternated between contrasting climatic conditions,having a dry climate during the period 990―1550 AD,a relatively humid climate during the Little Ice Age(LIA)(1550―1840 AD),and a dry climate again from 1840 AD onwards.At the decadal to centennial scale,a wet event around 1200―1230 AD,interrupting the generally arid period(990―1550 AD),and a dry event around 1590―1700 AD,punctuating the generally humid period(1550―1840 AD),are clearly documented.Trends in the chironomid-based salinity time series indicate a highly unstable climate during the LIA when salinity fluctuations were of greater magnitude and higher frequency.The effective moisture evolution in the Sugan Lake catchment during the last millennium reconstructed by chironomid analysis is in broad agreement with previous palaeo-moisture data derived from other sites in arid Northwest China(ANC).The LIA,characterized by generally humid conditions over the west-erly-dominated ANC was distinctly different from that in monsoonal China,implying an "out-of-phase" relationship between moisture evolution in these two regions during the past 1000 years.

关键词：西北干旱地区柴达木盆地古气候意义沉积物中国盐度纹层

On the timing of the East Asian summer monsoon maximum during the Holocene—Does the speleothem oxygen isotope record reflect monsoon rainfall variability?

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Science China Earth Sciences 2016年第12期59卷 2328-2338页

作者： chen JianHui RAO ZhiGuo LIU JianBao HUANG Wei FENG Song DONG GuangHui HU Yu XU QingHai chen fahu Key Laboratory of West China s Environmental System(Ministry of Education) College of Earth and Environmental SciencesLanzhou University Department of Geosciences University of Arkansas Institute of Nihewan Archaeology Research Hebei Normal University

The evolution of the East Asian summer monsoon(EASM) during the Holocene has long been of significant interest.Knowledge of past EASM variability not only increases our understanding of monsoon dynamics on a long timescale,but it also provides an environmental and climatic background for research into Chinese cultural development.However,the timing of the EASM maximum remains controversial.The popular concept of an "early Holocene maximum" is mainly based on speleothemδ18O(δ18Oc) records from caves in southern China;however,the interpretation of δ18OCas a reliable proxy for EASM intensity is being increasingly challenged.The present paper is a critical review of the climatic significance of the δ18OCrecord from China.Firstly,we suggest that precipitation in northern China is an appropriate index of EASM intensity,the variation of which clearly indicates a mid-Holocene monsoon maximum.Secondly,an interregional comparison demonstrates that the precipitation record in northern China is quite different from that in southern China on a range of timescales,and is inconsistent with the spatial similarity exhibited by speleothem oxygen isotope records.Furthermore,both modeling and observational data show that the δ18OCrecords from southern China indeed reflect changes in precipitation δ18O(δ18OP) rather than precipitation amount,and therefore that their use as an EASM proxy is inappropriate.Finally,we address several significant monsoon-related issues-including the driving mechanism of the EASM on an orbital timescale,the climatic significance of speleothem oxygen isotopes,and the relationship between atmospheric circulation and precipitation in monsoonal regions.

关键词： East Asian summer monsoon Holocene Speleothem oxygen isotopes

Effects of climate change and human activity on lake shrinkage in Gonghe Basin of northeastern Tibetan Plateau during the past 60 years

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Journal of Arid Land 2016年第4期8卷 479-491页

作者： WU Duo chen fahu LI Kai XIE Yaowen ZHANG Jiawu ZHOU Aifeng College of Earth and Environmental Sciences MOE Key Laboratory of Western China's Environmental SystemsLanzhou University

Changes in the status of freshwater resources are a topic of major global, regional and local concern. This is especially so in the arid and semi-arid regions of China, where shortage of water resources plays a crucial role in limiting sustainable socioeconomic development, as well as in sustaining natural ecosystems. Recent climate change, as well as the effects of localized human activity, such as the use of water for irrigation agriculture, may have significant effects on the status of the water resources in the region. Here, we report the results of a study of changes in the areas of lakes in Gonghe Basin, northeastern Tibetan Plateau of China, over the last 60 years. The data were acquired from optical satellite images and demonstrate that the total water area of lakes in Gonghe Basin decreased significantly from the 1950s to 1980s. The cause is ascribed mainly to human activity including exploitation of farmland, against a background of increasing population; in addition, climatic data for the region demonstrate a minor drying trend during this period as the temperature increased slightly. After the construction of several reservoirs, significant amounts of water were redistributed to promote irrigation agriculture and we conclude that this caused a significant shrinkage of the natural lakes. However, both the area of farmland and the population size remained approximately constant after 1990. We conclude that the variation of the total area of lakes during the second period was mainly controlled by climatic factors （precipitation and temperature）. As the regional temperature reached a new high, the area of some of the lakes decreased sharply before finally maintaining a relatively steady state. We emphasize that anthropogenic climate change and human activity have both significantly influenced the status of water resources in the arid and semi-arid regions of China.

关键词： Gonghe Basin lake shrinkage climate change human activity

Humid Medieval Warm Period recorded by magnetic characteristics of sediments from Gonghai Lake, Shanxi, North China

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Chinese Science Bulletin 2011年第23期56卷 2464-2474页

作者： LIU JianBao chen fahu chen JianHui XIA DunSheng XU QingHai WANG ZongLi LI YueCong Key Laboratory of Western China's Environmental System (Ministry of Education) Lanzhou University Lanzhou 730000 China College of Resources and Environment Hebei Normal University Shijiazhuang 0500161 China

Variations in monsoon strength, moisture or precipitation in eastern China during the MWP reflected by different climatic records have shown apparent discrepancies. Here, detailed environmental magnetic investigations and mineralogical analyses were conducted on lacustrine sediments of Core GH09B1 (2.8 m long) from Gonghai Lake, Shanxi, North China, concerning the monsoon history during the MWP. The results demonstrate that the main magnetic mineral is magnetite. The sediments with relatively high magnetic mineral concentrations were characterized by relatively fine magnetic grain sizes, which were formed in a period of relatively strong pedogenesis and high precipitation. In contrast, the sediments with low magnetic mineral concentrations reflected an opposite process. The variations of magnetic parameters in Gonghai Lake sediments were mainly controlled by the degree of pedogenesis in the lake drainage basin, which further indicated the strength of the Asian summer monsoon. The variations in the and S 300 parameters of the core clearly reveal the Asian summer monsoon history over the last 1200 years in the study area, suggesting generally abundant precipitation and a strong summer monsoon during the Medieval Warm Period (MWP, AD 910–1220), which is supported by pollen evidence. Furthermore, this 3–6-year resolution environmental magnetic record indicates a dry event around AD 980–1050, interrupting the generally humid MWP. The summer monsoon evolution over the last millennium recorded by magnetic parameters in sediments from Gonghai Lake correlates well with historical documentation (North China) and speleothem oxygen isotopes (Wanxiang Cave), as well as precipitation modeling results (extratropical East Asia), which all indicate a generally humid MWP within which centennial-scale moisture variability existed. It is thus demonstrated that environmental magnetic parameters could be used as an effective proxy for monsoon climate variations in high-resolution lacustrine sediments.

关键词：湖泊沉积物中世纪暖期磁性矿物中国北方潮湿特征记录山西季风强度