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Paleoglacial and paleoclimate reconstructions during the global Last Glacial Maximum in the Longriba area, eastern Tibetan Plateau

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Journal of Mountain Science 2021年第2期18卷 307-322页

作者： YANG Wei-lin HAN Ye-song PENG Xu RAN Ze-ze LIU Qing LIU Geng-nian College of Urban and Environmental Sciences Peking UniversityBeijing 100871China

Owing to the remoteness of the Longriba area and the lack of dating records,it is extremely challenging to reconstruct the chronology and extent of the paleoglaciers in this *** this paper,we combined limited observational data with automated modelling for paleoglacial *** first identified a broadly distributed paleoglacier from satellite imagery and field investigation based on the sediment-landform assemblage principle and dated it to 23.1±1.4~19.5±1.2 ka by ^(10)Be exposure dating,corresponding to the global Last Glacial Maximum(gLGM).Then,we reconstructed the extent and ice surface of 171 paleoglaciers formed during the similar period based on geomorphological evidence and‘ice surface profile’*** results showed that the paleoglacial coverage was 426.5 km2,with an ice volume of 38.1 km^(3),in the Longriba *** reconstructed equilibrium line altitudes(ELAs)based on modelled ice surfaces yielded an average of 4245±66 m above sea level(asl),~725±73 m lower than the present ELA(4970±29 m asl).The temperature was~5.51-6.68℃lower,and the precipitation was~30-34%less in Longriba,during the gLGM compared to the present *** glacial advance was mainly driven by colder climate that was synchronous with Northern Hemisphere cooling events.

关键词： Ice surface profile ^(10)Be surface exposure dating Paleoglacial reconstruction paleoclimate reconstruction Global Last Glacial Maximum Eastern Tibetan Plateau

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Latest Neogene paleoclimate Variation in Yunnan,Southwest China,Revealed by Fossil Leaf Physiognomy

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Acta Geologica Sinica(English Edition) 2023年第4期97卷 1268-1281页

作者： DAI Jing CHEN Weizhao HUANG Liang ZHANG Yi’nan School of Earth Science Yunnan UniversityKunming 650500China Ministry of Natural Resources Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization Kunming 650051China Yunnan Institute of Geological Survey Kunming 650216China Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of SciencesBeijing 100044China

Yunnan Province,located in the southeastern margin of the Tibetan Plateau,can provide important information on how climate change was influenced by global ***,its variation patterns in temperature and precipitation during the latest Neogene are not *** on the 357 specimens assigned to 31 morphotypes of plant fossils from the upper Pliocene Ciying Formation in Yiliang County,Yunnan Province,Southwest China,paleoclimate was estimated by Leaf Margin Analysis and Climate Leaf Analysis Multivariate *** to the present climate,the mean annual temperature and coldest month temperature have not changed significantly since the late Pliocene,whereas the warmest month temperature has decreased *** precipitation-related parameters have decreased,particularly winter *** with the climatic data of the same period in other areas of Yunnan,the western and eastern Yunnan has shown a similar pattern in temperature variation since the late Pliocene except for central Yunnan;whereas the variation in precipitation does not follow a common law except for a consistent decrease in winter *** study reinforced the fact that under the background of global cooling and intensified monsoon systems,different areas of Yunnan exhibit different climatic responses to these changes because of their topographic heterogeneities.

关键词： plant fossil paleoclimate reconstruction monsoon Pliocene Yunnan

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Influences of air CO2 on hydrochemistry of drip water and implications for paleoclimate study in a stream-developed cave, SW China

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Acta Geochimica 2016年第2期35卷 172-183页

作者： Xiaoxiao Wang Yanhong Wu Licheng Shen Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China University of Chinese Academy of Sciences Beijing 100049China School of Geographical Sciences Southwest UniversityChongqing 400715 China

Cave air CO_2 is a vital part of the cave environment. Most studies about cave air CO_2 variations are performed in caves with no streams; there are few studies to date regarding the relationship of cave air CO_2 variations and drip water hydrochemistry in underground stream–developed caves. To study the relationship of underground stream, drip water, and cave air CO_2, monthly and daily monitoring of air CO_2 and of underground stream and drip water was performed in Xueyu Cave from 2012 to *** results revealed that there was marked seasonal variation of air CO_2 and stream hydrochemistry in the cave. Daily variations of cave air CO_2, and of stream and drip water hydrochemistry, were notable during continuous monitoring.A dilution effect was observed by analyzing hydrochemical variations in underground stream and drip water after rainfall. High cave air CO_2 along with low p H and low δ^(13)C DIC in stream and drip water indicated that air CO_2 was one of the dominant factors controlling stream and drip water hydrochemistry on a daily scale. On a seasonal scale, stream flows may promote increased cave air CO_2 in summer; in turn, the higher cave air CO_2 could inhibit degassing of drip water and make calcite δ^(13)C more negative. Variation of calcite δ^(13)C(precipitated from drip water) was in reverse of monthly temperature, soil CO_2, and cave air CO_2. Therefore,calcite δ^(13)C in Xueyu Cave could be used to determine monthly changes outside the cave. However, considering the different precipitation rate of sediment in different seasons,it was difficult to use stalagmites to reconstruct environmental change on a seasonal scale.

关键词： Carbon dioxide - Underground stream Dripwater paleoclimate reconstruction Xueyu Cave

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Development background of Mesozoic high-quality source rocks: Evidence from microfossils in North Carnarvon Basin, Australia

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Petroleum Research 2019年第1期4卷 71-83页

作者： Xing Niu Xianghua Yang Detian Yan Xinguo Zhuang Bo Wang Shenjun Huo Xiaoming Xu Key Laboratory of Tectonics and Petroleum Resources of the Ministry of Education China University of Geosciences430074WuhanHubei ProvinceChina Faculty of Earth Resources China University of Geosciences430074WuhanHubei ProvinceChina CNOOC Research Institute Company Limited Beijing100028China

Based on numerous microfossils in Mesozoic of North Carnarvon Basin in Australia,the Mesozoic paleoclimate and paleoenvironment were analyzed,the paleogeographic background and development model of Mesozoic high-quality source rocks were investigated and *** of microfossil species and their relative contents in Mesozoic different intervals indicates changes of paleoclimate and *** paleoclimate shows a cycle variation of aridehumidearidehumid,the regression occurred in the Early TriassiceLate Triassic and the transgression occurred in the Late TriassiceLate *** sedimentary facieses including delta facies,littoral facies,restricted sea facies and open sea facies were developed in the *** open sea was mainly developed in the Early Triassic,the delta was distributed in the MiddleeLate Triassic,the restricted sea was especially well developed in the Jurassic,and the restricted sea and open sea were mainly distributed in the *** of microfossil assemblage in these four sedimentary facies are dramatically *** the delta facies,littoral facies,restricted sea facies to open sea facies,content of pollen gradually decreases,but content of the dinoflagellate+acritarch gradually *** delta facies and littoral facies are dominated by the *** the restricted sea facies,content of the pollen is equivalent to that of the dinoflagellate+*** open sea facies is dominated by the dinoflagellate and *** of sediment and formation of organic matter are influenced by the paleoclimate and paleoenvironment,and type of organic matter is controlled by the microfossil *** on the palaeogeographic background,paleoclimatic condition and microfossil assemblage,two developmental models of the Mesozoic source rocks such as the development model of terrestrial organic matter under the background of large delta and the development model of mixed organic matter under the

关键词： Microfossil assemblage Sporopollen Dinoflagellate and acritarchs paleoclimate reconstruction Evolution of sedimentary environment Development model of source rocks Mesozoic North Carnarvon basin

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Elevation-induced climate change as a dominant factor causing the late Miocene C4 plant expansion in the Himalayan foreland

Elevation-induced climate change as a dominant factor causin...

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中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： HAIBIN WU ZHENGTANG GUO JOЁL GUIOT CHRISTINE HATT CHANGHUI PENG YANYAN YU JUNYI GE QIN LI AIZHI SUN DEAI ZHAO Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences CNRS IRD CEREGE UM34 Aix-Marseille UniversitEurople de l’Arbois BP 80Aix-en-ProvenceCedex 4 F-13545 France Laboratory for Ecological Forecasting and Global Change College of Forestry Northwest A & F University

During the late Miocene, a dramatic global expansion of C4 plant distribution occurred with broad spatial and temporal variations. Although the event is well documented, whether subsequent expansions were caused by a decreased atmospheric CO2 concentration or climate change is a contentious issue. In this study, we used an improved inverse vegetation modeling approach that accounts for the physiological responses of C3 and C4 plants to quantitatively reconstruct the paleoclimate in the Siwalik of Nepal based on pollen and carbon isotope data. We also studied the sensitivity of the C3 and C4 plants to changes in the climate and the atmospheric CO2 concentration. We suggest that the expansion of the C4 plant distribution during the late Miocene may have been primarily triggered by regional aridification and temperature increases. The expansion was unlikely caused by reduced CO2 levels alone. Our findings suggest that this abrupt ecological shift mainly resulted from climate changes related to the decreased elevation of the Himalayan foreland.

关键词： C4 plant expansion inverse vegetation model paleoclimate reconstruction pollen biome late Miocene

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