Late glacial environment and climate development in northeastern China derived from geochemical and isotopic investigations of the varved sediment record from Lake Sihailongwan (Jilin Province) |
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| Authors: | Jörn Parplies Andreas Lücke Heinz Vos Jens Mingram Martina Stebich Ulrich Radtke Jingtai Han Gerhard H Schleser |
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| Institution: | 1.Institute of Chemistry and Dynamics of the Geosphere V: Sedimentary Systems,Research Centre Juelich,Juelich,Germany;2.Department of Geography,University of Cologne,Cologne,Germany;3.GeoForschungsZentrum (GFZ),Potsdam,Germany;4.Forschungsinstitut Senckenberg,Forschungsstation für Quart?rpal?ontologie Weimar,Weimar,Germany;5.Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,China |
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| Abstract: | Total organic carbon (TOC) content, total nitrogen (TN) content, stable nitrogen isotope (δ15N) and stable organic carbon isotope (δ13Corg) ratios were continuously analysed on a high resolution sediment profile from Lake Sihailongwan (SHL), covering the time
span between 16,500 and 9,500 years BP. Strong variations of the investigated proxy parameters are attributed to great climatic
fluctuations during the investigated time period. Variations in organic carbon isotope ratios and the ratio of TOC/TN (C/N
ratio) are discussed with respect to changing proportions of different organic matter (OM) sources to bulk sedimentary OM.
Phases of high TOC content, high TN content, depleted δ13Corg values and high δ15N values are interpreted as times with increased productivity of lacustrine algae in relation to input of terrigenous organic
matter. Two distinct phases of enriched nitrogen isotope ratios from 14,200 to 13,700 and 11,550 to 11,050 years BP point
towards a reduced phytoplankton discrimination against 15N due to a diminished dissolved inorganic nitrogen pool. The combination of geochemical (TOC, TN, C/N ratio) and isotopic
(δ13Corg, δ15N) proxy parameters points to a division of climate development into four stages. A cold and dry stage before 14,200 years
BP, a warm optimum stage with high phytoplankton productivity from 14,200 to 12,450 BP, a colder and drier stage from 12,450
to 11,600 BP and a stage of climatic amelioration with high variability in TOC and TN contents after 11,600 BP. These results
are discussed in relation to monsoon variability and Northern Hemisphere climate development of the late glacial. |
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| Keywords: | Stable isotopes δ 13Corg δ 15N Late glacial East Asian monsoon Climate variability |
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