AUTHIGENIC CARBONATE SEDIMENTATION IN ERAVNOE GROUP LAKES (western Transbaikalia): RESPONSE TO HOLOCENE CLIMATE CHANGE
E.P. Solotchina1, E.V. Sklyarov2,3, P.A. Solotchin1, L.V. Zamana4, I.V. Danilenko1, O.A. Sklyarova5, P.G. Tat’kov6
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia
3Far East Federal University, ul. Sukhanova 8, Vladivostok, 690950, Russia
4Institute of Natural Resourses, Environment, and Cryology, Siberian Branch of the Russian Academy of Sciences, ul. Butina 26, Chita, 672090, Russia
5Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, 664033, Irkutsk, Russia
6Geological Institute, Siberian Branch of the Russian Academy of Sciences, ul. Sakhyanovoi 6a, Ulan-Ude, 670047, Russia
Keywords: Bottom sediments, carbonates, XRD analysis, infrared spectroscopy, 18O and 13C isotopes, Late Holocene, paleoclimate, Lake Dolgoe, Eravnoe basin, East Siberia
Abstract
Sediments of intracontinental closed lakes are unique natural archives that store climate history records. We study Late Holocene carbonate-bearing sediments of Lake Dolgoe, a small saline lake in the Eravnoe basin on the Vitim Plateau (western Transbaikalia). Sediment samples have been analyzed by several methods: powder X-ray diffractometry, Infrared spectroscopy, stable isotope (18O and 13C) determination, laser diffraction particle size analysis, XRF elemental analysis, etc. The mineral phases of bottom sediments include clastic and carbonate components and hydromagnesite at the section top; carbonates are authigenic varieties of the calcite-dolomite series. Modeling of complex XRD profiles reveal Mg-calcite with various Mg contents and excess-Ca dolomites which are mixed-structure crystals compositionally close to stoichiometric dolomite. The crystal structure and relative percentages of carbonates from the dated sedimentary section controlled by climate and lake level changes allow reconstructing the Holocene history of Lake Dolgoe.
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