EARLY DIAGENESIS GEOCHEMISTRY OF BOTTOM SEDIMENTS IN THE PLEISTOCENE CORE OF LAKE KOTOKEL (Eastern Baikal Region)
Leonova G.A. Maltsev A.E. Kondratieva L.M. Bychinsky V.A. Miroshnichenko L.V. Krivonogov S.K.
December 2024Publishing House of Siberian Branch of the Russian Academy of Sciences
Russian Geology and Geophysics
2024#65Issue 121446 - 1467 pp.
Chemical composition of bottom sediments and pore waters of organic-mine-ral sediments (sapropel) of Lake Kotokel (Eastern Baikal region) has been studied, based on long drilling cores, 14.5 and 16.5 m. A reduction type of diagenesis has been established, during which destruction of organic matter, transformation of the chemical composition of pore waters and the formation of authigenic minerals oc-cur. Even in the uppermost intervals of sapropel, organic matter is being profound-ly transformed and differs significantly in composition from that of bioproducers (plankton). The major role in diagenetic transformations of organic matter belongs to different physiological groups of microorganisms, primarily heterotrophic, amonify-ing and sulfate-reducing bacteria. During diagenesis, the basic chemical composition of pore waters (HCO3–, SO42–, Cl–, Ca2+, Mg2+, K+, Na+) changes, trace elements (Fe, Mn, Sr, Ba, Pb, As, Co, Ni) redistribute, concentrations of HCO3–, NH4+, PO4 3– and Si increase; this is caused by destruction of organic matter. In the process of bacterial sulfate reduction in pore waters, the concentration of SO4 2– decreases along the depth of the section, and in the sediment the proportion of reduced forms of sulfur increases and the isotopic composition of sulphur δ34S changes. Transformation of chemical composition of pore waters and the activity of microorganisms leads to the formation of authigenic pyrite, rhodochrosite, and barite.
authigenic mineral formation , early diagenesis , Geochemistry , organic matter , pore waters , sulfate reduction
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V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciencespr, Akademika Koptyuga 3, Novosibirsk, 630090, Russian Federation
Institute for Water and Environmental Problems, Far Eastern Branch of the Russian Academy of Sciencesul, Dikopol’tseva 56, Khabarovsk, 680000, Russian Federation
Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russian Federation
Korkyt Ata Kyzylorda University, Aiteke bi 29A, Kyzylorda, 120014, Kazakhstan
V.S. Sobolev Institute of Geology and Mineralogy
Institute for Water and Environmental Problems
Vinogradov Institute of Geochemistry
Korkyt Ata Kyzylorda University
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