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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： Northeastern Tajik Basin Paleogene Eolian deposits Paratethys aridification

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Onset of Xiashu loess deposition in southern China by 0.9 Ma and its implications for regional aridification

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Science China Earth Sciences 2018年第3期61卷 256-269页

作者： Xusheng LI Zhiyong HAN Huayu LU Yingyong CHEN Yang LI Xiaokang YUAN Yuwen ZHOU Mengyao JIANG Cunjuan LV School of Geographic and Oceanographic Sciences Nanjing University Nanjing 210023 China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101 China College of Environment and Planning Henan University Kaifeng 475001

The Xiashu loess is a typical Quaternary eolian deposit in southem China and represents an important terrestrial paleoclimate archive in this low-latitude monsoon region. However, the chronological framework of Xiashu loess deposition has yet to be established. Determining the timing of the onset of Xiashu loess deposition will allow researchers to better understand late Quaternary aridification across the Asian continent, the evolution of the East Asian monsoon and regional environmental changes in subtropical regions. Therefore, in this study, a systematic chronological study of the Xiashu loess is conducted to answer this question. For the first time, magnetostratigraphic classification reveals that the Matuyama/Bnmhes （M/B） reversal is present in the Xiashu loess at two sites in Jiangsu Province, the Qingshan profile at Yizheng and the Dagang core in Zhenjiang. Based on the results of magnetostratigraphy and optically stimulated luminescence （OSL） dating, the age of the lower boundary of the Xiashu loess is estimated to be approximately 0.9 Ma. Consequently, this Xiashu loess deposit is the oldest reported to date and is comparable in age to the red soil deposit in Xuancheng, Anhui Province. The onset of Xiashu loess deposition by 0.9 Ma represents the further expansion of arid range in Asia in the late Quaternary in response to significant aridification and winter monsoon strengthening in this subtropical region. We suggest that these climate changes were primarily driven by global cooling and an increase in high-latitude ice volume in the Northern Hemisphere and that the initiation of Xiashu loess accumulation was a regional response of southern China to the 0.9 Ma global cooling event.

关键词： Xiashu loess Chronology Magnetic stratigraphy aridification East Asian monsoon

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Late Miocene stepwise aridification in the Asian interior and the interplay between tectonics and climate

Late Miocene stepwise aridification in the Asian interior an...

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中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： Jimin Sun Zhijun Gong Zhonghua Tian Yingying Jia Brian Windley Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences Department of Geology The University of Leicester

The mid-latitudinal central Asian continent is characterized by large sand deserts and Gobi(stony desert). In this context, it is of interest to study the timing and forcing mechanisms of aridification in the region. Here we present multiple geochemical climatic proxies from late Cenozoic strata in the Tarim Basin of northwestern China, a region sensitive to climatic change. The results yield long-term climatic records covering a time interval of 13.3 to2.5 Ma. We find that a general trend towards a dry climate was superimposed by two stepwise aridification events, the first lesser aridity phase occurred at 7–5.3 Ma and the second extreme aridity episode was initiated at 5.3 Ma. Based on the correlation between climatic change and regional tectonic events, we propose a mechanism to explain the climatic variations. The general long-term drying trend since the mid-Miocene was a response to global climatic cooling, while the stepwise aridification since the latest Miocene was controlled mainly by regional tectonic uplift.

关键词： Late Cenozoic aridification Paleoclimate Forcing mechanism Central Asia

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Evidence of late early Miocene aridification intensification in the Xining Basin caused by the northeastern Tibetan Plateau uplift

Evidence of late early Miocene aridification intensification...

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中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： Chunxia Zhang Guoqiao Xiao Zhengtang Guo Haibin Wu Qingzhen Hao Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences

Few early Miocene terrestrial climate records exist from the Asian interior and as a result the evolution of Central Asian aridification and the driving forces behind it remain unclear. Here we report sedimentary, mineralogy and geochemical proxies from an early Miocene sedimentary sequence(ca. 22.1 to 16.5 Ma) from Xining Basin on the northeastern side of the Tibetan Plateau. Multiple proxies indicate a change of sedimentary facies of a distal alluvial fan from subfluvial to subatmospheric under a dominantly arid climate coupled with a clear two-stage climate change. During 22.1–19.7 Ma(Unit I), the enrichment of I/S(irregular mixed-layers of illite and smectite) content, high values of a*/L*(redness/lightness), and stronger degree of chemical weathering suggest relatively warm and humid climate conditions during a generally arid climate. During 19.7–16.5 Ma(Unit II), the increase of chlorite and dolomite content, the upward decrease of a*/L*, and weaker degree of chemical weathering than Unit I suggest gradually increasing aridity since ca. 19.7 Ma. Comprehensive comparisons among records from central western China demonstrate that the aridification since ca. 19.7 Ma is widespread in northeastern part of the Tibetan Plateau. The climate changes in inner Asia are different to that of globalscale changes, which indicates that global climate changes and the retreat of the Para-Tethys Sea possibly had little influences on this region. The episodic, but persistent tectonic uplift of the north and northeastern Tibetan Plateau during the early Miocene likely played a key role in the aridification of the Xining Basin.

关键词： Inner Asia Early Miocene Clay minerals aridification Tibetan Plateau uplift

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Phylogeography of the desert scorpion illuminates a route out of Central Asia

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Current Zoology 2023年第4期69卷 442-455页

作者： Cheng-Min SHI Xue-Shu ZHANG Lin LIU Ya-Jie JI De-Xing ZHANG State Key Laboratory of North China Crop Improvement and Regulation College of Plant ProtectionHebei Agricultural UniversityBaoding 071001China State Key Laboratory of Integrated Management of Pest Insects and Rodents Institute of ZoologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences 19 Yuquan RoadBeijing 100049China

A comprehensive understanding of phylogeography requires the integration of knowledge across different organisms,ecosystems,and geographic ***,a critical knowledge gap exists in the arid biota of the vast Asian *** narrow this gap,here we test an“out-of-Central Asia”hypothesis for the desert scorpion Mesobuthus mongolicus by combining Bayesian phylogeographic reconstruction and ecological niche *** analyses of one mitochondrial and three nuclear loci and molecular dating revealed that *** represents a coherent lineage that diverged from its most closely related lineage in Central Asia about 1.36 Ma and underwent radiation ever *** phylogeographic reconstruction indicated that the ancestral population dispersed from Central Asia gradually eastward to the Gobi region via the Junggar Basin,suggesting that the Junggar Basin has severed as a corridor for Quaternary faunal exchange between Central Asia and East *** major dispersal events occurred probably during interglacial periods(around 0.8 and 0.4 Ma,respectively)when climatic conditions were analogous to present-day status,under which the scorpion achieved its maximum distributional *** underwent demographic expansion during the Last Glacial Maximum,although the predicted distributional areas were smaller than those at present and during the Last *** of desert ecosystems in northwest China incurred by intensified aridification might have opened up empty habitats that sustained population *** results extend the spatiotemporal dimensions of trans-Eurasia faunal exchange and suggest that species’adaptation is an important determinant of their phylogeographic and demographic responses to climate changes.

关键词： aridification ecological niche modeling drylands Mesobuthus Pleistocene population expansion

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The Mid-Miocene Pollen Record of the Xunhua Basin, NE Tibetan Plateau: Implications for Global Climate Change

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Acta Geologica Sinica(English Edition) 2015年第5期89卷 1649-1663页

作者： XU Zenglian ZHANG Jianyu JI Junliang ZHANG Kexin School of Earth Sciences China University of GeoscienceWuhan State Key Laboratory of Biogeology and Envicronmental Geology China University of GeoscienceWuhan China Geological Survey Wuhan Center

The northeastern Tibetan Plateau is located at the convergence of the Asian winter and summer monsoons and westerlies; thus, this area has witnessed historic climate *** Xunhua basin is an intermontane basin on the northeastern margin of the Tibetan *** basin contains more than 2000 m of Cenozoic fluvial–lacustrine sediments, recording a long history of climate and environmental *** collected the mid-Miocene sediments from the Xunhua basin and used palynological methods to discuss the relationship between aridification in the interior of Asia, global cooling, and uplift of the Tibetan *** on the palynological analysis of the Xigou section, Xunhua basin, the palynological diagram is subdivided into three pollen zones and past vegetation and climate are *** I, Ephedripites–Nitraridites–Chenopodipollis–Quercoidites（14.0–12.5 Ma）, represents mixed shrub–steppe vegetation with a dry and cold *** zone II, Pinaceae–Betulaepollenites–Ephedripites–Chenopodipollis–Graminidites（12.5–8.0 Ma）, the vegetation and climate conditions improved, even though the vegetation was still dominated by shrub–steppe *** III, Ephedripites–Nitrariadites–Chenopodipollis（8.0–5.0 Ma）, represents desert steppe vegetation with drier and colder *** palynological records suggest that shrub–steppe dominated the whole Xigou section and the content gradually increased, implying a protracted aridification process, although there was an obvious climate improvement during 12.5–8.0 *** aridification in the Xunhua basin and surrounding mountains during 14.0–12.5 Ma was probably related to global cooling induced by the rapid expansion of the East Antarctic ice-sheets and the relatively higher evaporation *** the 12.5–8.0 Ma period, although topographic changes（uplift of Jishi Shan） decreased precipitation and strengthened aridification in the Xunhua basin on leeward slopes, the improved vegetation and climate conditions were probab

关键词： pollen mid-miocene aridification Xunhua basin northeastern Tibetan Plateau

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Loess in the Tian Shan and its implications for the development of the Gurbantunggut Desert and drying of northern Xinjiang

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Chinese Science Bulletin 2002年第16期47卷 1381-1387页

作者： FANG Xiaomin SHI Zhentao YANG Shengli YAN Maodu LI Jijun JIANG Ping’an National Laboratory of Western China’s Environmental Systems of Ministry of Education of China&Department of Geography Lanzhou UniversityLanzhou 730000China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710054China Institute of Cold and Arid Region&Environment and Engineering of Chinese Academy of Sciences Lanzhou 730000China Department of Geological Sciences University of MichiganAnn ArborMI 48103USA School of Agriculture Xinjiang Agriculture UniversityUrumqi 830000China

Eolian loess is widely distributed on the various geomorphic surfaces between 700-2400 m a.s.l. on the northern slope of the Tian Shan. It is formed in a synchronous manner with dust transported from the Gurbantunggut Desert in the Junggar Basin. The thickest section of loess was found in the Shawan and Shihezi regions. Paleomagnetic and climatic proxy analyses of over 71 m of a loess-paleosol sequence on the highest terrace of the Qingshui He (River) in the Shawan show that the paleomagnetic Bruhues/Matuy-ama (B/M) boundary lies at the bottom of paleosol S8, at a depth of 69.5 m, and the bottom of the sequence was estimated to be -0.8 Ma. This implies that the extremely dry climatic conditions in the Junggar Basin and the initial Gurbantunggut Desert were present at least by 0.8 Ma. High-resolution grain size series demonstrate that this area and desert expansion experienced two dramatic periods of desert expansions that occurred at -0.65 Ma and 0.5 Ma, respectively; and the subsequent continuous

关键词： Tian Shan loess Gurbantunggut Desert aridification global change.

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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.

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

Extension of drylands in northern China around 250 kaBP link...

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中国科学院地质与地球物理研究所2002学术年会

作者： Wu haibin~a Guo Zhengtang~c Fang Xiaomin~(bc) Zhang Jiawu~b and Chen Fahu~b a Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China b.Department of Geography,Lanzhou University,Lanzhou 730000,China c.Institute of Earth Environment,Chinese Academy of Sciences,Xi’an 710075,China

Study on two 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 *** 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 *** 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 *** 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,*** 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 *** decrease in monsoon moisture is attributable to the uplift of the Hengduan Mountains,the southeast margin of the Tibetan Plateau at～250 ka ago.

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

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从模拟研究看青藏高原的隆升形式与亚洲季风——干旱环境演化的区域差异（英文）

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地球环境学报 2011年第3期2卷 401-416页

作者：刘晓东尹志勇 State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of Sciences Xi'an Jiaotong University University of San Diego

Tectonic uplift of the Tibetan Plateau(TP) is a major event in the recent geological history of the earth,which produced far-reaching impacts on the Asian and global climates and *** the 1970 s,with the development of theories in planetary fluid dynamics and the improvement of computational environment,numerical simulation based on general circulation models(GCMs) has become an increasingly effective tool in investigations of the physical mechanisms and evolutionary processes of paleoclimate associated with the TP *** this paper,we provide a timely review on representative works in the past four decades on the paleoclimatic responses to the plateau *** simulations to study the paleoclimatic effects of the plateau uplift experienced three stages with increasing complexity:1) plateau uplift as a whole in a single episode,as represented by the no-mountain/with-mountain experiments;2) phased uplift in which the uplifting process was divided into multiple stages and within each the plateau rose by a certain proportion of its current height;and3) sub-regional uplift,in which the focus was the effects of the uplift of a certain area within the TP,such as the northern Tibetan *** studies discovered the cause-effect relations between the plateau uplift and paleoclimate change,especially for the effects on the evolution of Asian monsoon system and aridification of inland *** this review,we also included examples of current on-going studies,such as the relative impacts of the Himalayas *** of the TP as the rain barrier and comparative studies on the paleoclimatic effects of the uplifts of the TP and African *** the end,we identified five areas as the focus of future research regarding the TP uplift:1) the differences in the evolutionary processes of the South Asian and East Asian monsoons in response to the Himalayas-TP uplift at the regional and sub-regional scales;2) climatic feedbacks;3) long-distance effects(

关键词： tectonic uplift Tibetan plateau paleoclimate modeling Asian monsoon aridification

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