E. P. Solotchina

Climatic signals in the Holocene carbonate sedimentary record of Namshi-Nur lake, West Baikal region

A new high-resolution Holocene climate record of the Western Baikal region from the evaporite sediments of one of the small saline lakes with the carbonate type of sedimentation are obtained on the basis of detailed mineralogical and crystallochemical studies of chemogenic carbonates. All carbonate phases occurring in the sediment are identified by decomposition of complex XRD-profiles of carbonates into individual peaks using the Pearson VII function, and the quantitative relationships between them are determined. Mg-calcites provide the major paleoclimatic information. The carbonate record contains data on the stratigraphic distribution of Mg-calcites, in which the number and ratio between the phases of different magnesium contents are determined by the past values of the Mg/Ca ratio, salinity, and total alkalinity of lake water that vary according to climatic cycles and fluctuations of the lake level. The high potential of the approach proposed for paleoclimatic reconstructions is demonstrated.

Holocene climate history of the Western Baikal region: Carbonate sedimentary record of Kholbo-Nur Lake

ISSN 1028334X, Doklady Earth Sciences , 2010, Vol. 431, Part 2, pp. 490–496.

Mineralogy and crystal chemistry of carbonates in modern sediments of shallow lakes of Olkhon area (Baikal region)

The high degree of the influence of regional cli� matic and natural factors on sedimentation in intrac� ontinental water reservoirs necessitates a comprehen� sive study of their bottom sediments during paleocli� matic reconstructions. Shallow lake basins of the arid and semiarid zones with intense carbonate accumula� tion are quite promising in the world practice for reconstruction of the climate in the Holocene. The small sizes of lakes determine their exclusive sensitiv� ity to environmental changes impacted in sedimentary records. It is considered that deposition of one car� bonate or another proceeds from waters oversaturated in carbonate and is controlled by a number of factors: Mg 2+ /Ca 2+ in water, carbonate alkalinity (concentra� tions of HCO , CO , and H2CO3), salinity, pH, tem� perature, and organic productivity of the lake, which are controlled by the water balance depending on the climatic conditions [1, 2]. In recent years, we have worked out a new approach to paleoclimatic recon� structions based on detailed mineralogical and crystal chemical studies of endogenic carbonates from lake sediments. Identification of an association of carbon� ate minerals, their crystal chemical and structural peculiarities, and regularities in the distribution of individual carbonate phases in dated sedimentary sequences of shallow lakes allowed us to obtain a num�

Carbonate sedimentation in shallow saline lakes of Western Transbaikalia: The response to Holocene climate changes

New research results are presented on the processes of carbonate sedimentation in shallow saline lakes of Western Transbaikalia by the example of the Holocene bottom sediments of Sul’fatnoe Lake (the Selenga Dauria). The techniques of X-ray diffractometry (XRD), IR spectroscopy, laser granulometry, and isotope and elemental analyses were used. By means of decomposition the XRD profiles using the Pearson VII function, the carbonate phases were identified and their quantitative ratios were determined. The evolution of the lake basin caused by climate changes in the Holocene was reconstructed by comparing the carbonate record to the concentrations determined for the 18O and 13C stable isotopes and to lithological, geochemical, and palynological data in the dated sedimentary section.