Holocene environments and climate in the Mongolian Altai reconstructed from the Hoton-Nur pollen and diatom records: a step towards better understanding climate dynamics in Central Asia |
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| Authors: | Natalia Rudaya Pavel Tarasov Nadezhda Dorofeyuk Nadia Solovieva Ivan Kalugin Andrei Andreev Andrei Daryin Bernhard Diekmann Frank Riedel Narantsetseg Tserendash Mayke Wagner |
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| Institution: | 1. Institute of Archaeology and Ethnography SB RAS, Ak. Lavrentieva Str. 17, 630090 Novosibirsk, Russia;2. Novosibirsk State University, Pirogova Str. 2, 630090 Novosibirsk, Russia;3. Altai State University, Dimitrova Str. 66, 656049 Barnaul, Russia;4. Kazan Federal University, Kremlevskaya Str. 18, 420008 Kazan, Russia;5. University of Potsdam, Institute of Earth and Environmental Science, Karl Liebknecht Str. 24-25, 14476 Potsdam, Germany;6. Department of Geography, Moscow State University, Vorobievy Gory 1, 119991 Moscow, Russia;7. Institute of Geography Russian Academy of Science, Staromonetny lane, 29, 119017 Moscow, Russia;8. Institute for Geology and Mineralogy, University of Cologne, Zülpicher Str. 49a, 50674 Cologne, Germany;9. Sobolev Institute of Geology and Mineralogy SB RAS, Ak. Koptyuga Str. 3, 630090 Novosibirsk, Russia;10. Department of Geosciences, National Taiwan University, Taipei 106, Taiwan, ROC;1. State Key Laboratory of Loess and Quaternary Geology, IEE, CAS, Xi''an 710075, China;2. Key Laboratory of Salt Lake Resources and Chemistry, Qinghai Institute of Salt Lake, Chinese Academy of Sciences, Xining, Qinghai 810008, China;3. University of Chinese Academy of Sciences, Beijing 100049, China;4. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, China;5. Department of Geology and Environmental Earth Science, Miami University, Oxford, OH 45056, USA;6. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;7. Department of Marine Sciences, The University of Georgia, Athens, GA 30602, USA;8. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China;9. Department of Earth Sciences, The University of Hong Kong, Hong Kong, China;10. Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education/Qingdao Collaborative Innovation Center of Marine Science and Technology, Qingdao 266100, China;11. School of Human Settlement and Civil Engineering, Xi''an Jiaotong University, Xi''an 710049, China;1. College of Environment and Resources, Inner Mongolia University, Huhhot 010021, China;2. Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China;1. Department of Earth Sciences, The University of Hong Kong, Hong Kong, China;2. School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK;3. Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, PA 18015, USA;4. Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia;5. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Science, Xi''an 710075, China;6. MOE Key Laboratory of Western China''s Environmental System, Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou 730000, China;1. MOE Key Laboratory of West China''s Environmental System, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China;2. State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730000, China;3. Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China;4. College of Resources and Environmental Sciences, Hunan Normal University, Changsha 410081, China;5. Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China |
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| Abstract: | This study presents the results of the palynological and diatom analyses of the sediment core recovered in Hoton-Nur Lake (48°37′18″N, 88°20′45″E, 2083 m) in 2004. Quantitative reconstruction of the Holocene vegetation and climate dynamics in the semiarid Mongolian Altai suggests that boreal woodland replaced the primarily open landscape of northwestern Mongolia at about 10 kyr BP (1 kyr = 1000 cal yr) in response to a noticeable increase in precipitation from 200–250 mm/yr to 450–550 mm/yr. A decline of the forest vegetation and a return to a predominance of open vegetation types occurred after 5 kyr BP when precipitation sums decreased to 250–300 mm/yr. Prior to 11.5 kyr BP diatom concentrations are relatively low and the lake is dominated by planktonic Cyclotella and small Fragilariaceae, suggesting the existence of a relatively deep and oligotrophic/mesotrophic lake. The great abundance of Staurosirella pinnata from the beginning of the record until 10.7 kyr BP might imply intensified erosion processes in the catchment and this is fully consistent with the presence of scarce and dry vegetation and the generally arid climate during this period. From about 10.7 kyr BP, more planktonic diatom taxa appeared and increased in abundance, indicating that the lake became more productive as diatom concentration increased. This change correlates well with the development of boreal woodland in the catchment. Decrease in precipitation and changes in the vegetation towards steppe are reflected by the rapid increase in Aulacoseira distans from about 5 kyr BP. The Holocene pollen and diatom records do not indicate soil and vegetation cover disturbances by the anthropogenic activities, implying that the main transformations of the regional vegetation occurred as a result of the natural climate change. Our reconstruction is in agreement with the paleomonsoon records from China, demonstrating an abrupt strengthening of the summer monsoon at 12 kyr BP and an associated increase in precipitation and in lake levels between 11 and 8 kyr BP, followed by the stepwise attenuation of the monsoon circulation and climate aridization towards the modern level. The records from the neighboring areas of Kazakhstan and Russia, situated west and north of Hoton-Nur, demonstrate spatially and temporally different Holocene vegetation and climate histories, indicating that the Altai Mountains as a climate boundary are of pivotal importance for the Holocene environmental and, possibly, habitation history of Central Asia. |
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