MINERALOGY OF HOLOCENE SEDIMENTS OF LAKE BOLSHOE YAROVOE (SOUTH OF WESTERN SIBERIA): THE ROLE OF THE CLIMATIC FACTOR
P.A. Solotchin1, E.P. Solotchina1, A.E. Maltsev1, G.A. Leonova1, A.N. Zhdanova1, S.K. Krivonogov1,2, I.V. Danilenko1
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences,
Novosibirsk, Russia
2Korkyt-Ama Kyzylordinsky University, Kyzylorda, Kazakhstan
Keywords: hypersaline lake, Holocene, bottom sediments, mineralogy, XRD analysis, carbonates, crystal chemistry, paleoclimate, Western Siberia
Abstract
The article presents the results of lithological and mineralogical studies of Holocene bottom sediments from the hypersaline Lake Bolshoe Yarovoe (salinity of 150 g/L), located on the territory of the Kulunda steppe (south of Western Siberia). Research methods: X-ray diffractometry (XRD), IR spectroscopy, laser grain-size analysis, elemental analysis, radiocarbon dating. The thickness of the uncovered sediments is 483 cm. Terrigenous minerals throughout the section are represented by quartz, plagioclase, and layered silicates (mica, chlorite, smectite, and kaolinite). Among the autigenic minerals, halite, gypsum, carbonates, and traces of pyrite are present everywhere in variable amounts. Mathematical modeling of XRD profiles in the assemblage of carbonate minerals identified Mg-calcites with different Mg contents and aragonite. The mineralogical and crystallochemical studies of sediments supplemented by the results of other analyses have provided information about the evolution of the climate of the Kulunda steppe in the Middle to Late Holocene. The comparatively arid regional climate of the Middle Holocene changed to a more humid one in the first half of the Subatlantic, but signs of aridization reappeared in the section about 600 years ago (Little Ice Age).
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