1. Mineralogical Indicators of the Holocene Climate in Sediments of the High-Mountain Lake Sagan-Nur (East Sayan Mountains).
- Author
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Solotchina, E. P., Solotchin, P. A., Bezrukova, E. V., Zhdanova, A. N., Shchetnikov, A. A., Danilenko, I. V., and Kuzmin, M. I.
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LAKE sediments , *HOLOCENE Epoch , *COMPOSITION of sediments , *X-ray diffraction , *ORE deposits , *QUARTZ , *PLAGIOCLASE , *KAOLINITE , *MOUNTAINS - Abstract
The results of studying bottom sediments taken from the high-mountain lake Sagan-Nur located on the Oka plateau (East Sayan Mountains), which is insufficiently studied, are presented. The lake is freshwater and has a glacial origin. Comprehensive investigations of the mineral composition of the lake sediments accumulated over the past ~8600 cal. years have been carried out for the first time. The research methods include X-ray diffraction (XRD), infrared spectroscopy, laser granulometry, SiO2 bio determination, AMS, and 210Pb dating. The mineral composition of the bottom sediments is dominated by layered silicates, quartz, and plagioclase; furthermore, the X-ray amorphous component consisting of biogenic silica and organic matter is present. The method of mathematical modeling of their complex XRD patterns is used for correct identification of the layered silicates. It is established that the layered silicate assemblage is stable and is represented by muscovite, chlorite, illite, mixed-layer illite–smectite and chlorite–smectite, and kaolinite. At the same time, the structural characteristics and quantitative ratios of these minerals in the deposits changed significantly in response to changes in the natural environment of the region, which reveals the potential of a number of phyllosilicates (illite, mixed-layer minerals) as indicators of the paleoclimate in the bottom sediments of freshwater basins. The results of studying the sediment composition and, especially, the precision mineralogical–crystallochemical analysis of layered silicates have made it possible to reconstruct the paleolandscapes and climatic conditions of sediment accumulation and to assign them to the respective Holocene sub-stages. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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