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Lateglacial and Holocene environmental history of the central Kola region,northwestern Russia revealed by a sediment succession from Lake Imandra |
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| Authors: | Matthias Lenz Larisa Savelieva Larisa Frolova Anna Cherezova Matthias Moros Marlene M Baumer Raphael Gromig Natalia Kostromina Niyaz Nigmatullin Vasili Kolka Benrd Wagner Grigory Fedorov Martin Melles |
| Institution: | 1. Institute of Geology and Mineralogy, University of Cologne, Zülpicher Str. 49a, Cologne, D-50674, Germany;2. St. Petersburg State University, Universitetskaya Nab. 7/9, St. Petersburg, 199034, Russia;3. Laboratory of Paleoclimatology, Paleoecology, Paleomagnetism, Kazan Federal University, Kremlevskaya Street 18, Kazan, 420008, Russia;4. Karpinski Russian Geological Research Institute, Sredny Prospect 74,, St. Petersburg, 199106, Russia;5. Leibniz Institute for Baltic Sea Research Warnemünde, Seestrasse 15, Rostock, D-18119, Germany;6. St. Petersburg State University, Universitetskaya Nab. 7/9, St. Petersburg, 199034, Russia
Gramberg All-Russia Scientific Research Institute for Geology and Mineral Resources of the Ocean (VNIIOkeangeologia), Angliyskiy av., 1, St. Petersburg, 190121 Russia;7. St. Petersburg State University, Universitetskaya Nab. 7/9, St. Petersburg, 199034, Russia Arctic and Antarctic Research Institute, Bering Str. 38, St. Petersburg, 199397 Russia |
| Abstract: | Bolshaya Imandra, the northern sub-basin of Lake Imandra, was investigated by a hydro-acoustic survey followed by sediment coring down to the acoustic basement. The sediment record was analysed by a combined physical, biogeochemical, sedimentological, granulometrical and micropalaeontological approach to reconstruct the regional climatic and environmental history. Chronological control was obtained by 14C dating, 137Cs, and Hg markers as well as pollen stratigraphy and revealed that the sediment succession offers the first continuous record spanning the Lateglacial and Holocene for this lake. Following the deglaciation prior to c. 13 200 cal. a BP, the lake's sub-basin initially was occupied by a glacifluvial river system, before a proglacial lake with glaciolacustrine sedimentation established. Rather mild climate, a sparse vegetation cover and successive retreat of the Scandinavian Ice Sheet (SIS) from the lake catchment characterized the Bølling/Allerød interstadial, lasting until 12 710 cal. a BP. During the subsequent Younger Dryas chronozone, until 11 550 cal. a BP, climate cooling led to a decrease in vegetation cover and a re-advance of the SIS. The SIS disappeared from the catchment at the Holocene transition, but small glaciers persisted in the mountains at the eastern lake shore. During the Early Holocene, until 8400 cal. a BP, sedimentation changed from glaciolacustrine to lacustrine and rising temperatures caused the spread of thermophilous vegetation. The Middle Holocene, until 3700 cal. a BP, comprises the regional Holocene Thermal Maximum (8000–4600 cal. a BP) with relatively stable temperatures, denser vegetation cover and absence of mountain glaciers. Reoccurrence of mountain glaciers during the Late Holocene, until 30 cal. a BP, presumably results from a slight cooling and increased humidity. Since c. 30 cal. a BP Lake Imandra has been strongly influenced by human impact, originating in industrial and mining activities. Our results are in overall agreement with vegetation and climate reconstructions in the Kola region. |
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