O. A. Sklyarova

Carbonates in the sedimentary record of saline Tsagan-Tyrm Lake, west Baikal region: New type of high-resolution paleoclimatic signals

The reasons for catastrophic climate warming have been a matter of heated debates for the past few decades. The issue of the decisive role of anthropogenic factors or natural fluctuations in modern warming can be solved correctly only from paleoclimatic reconstructions, which are mainly based on study of bottom sediments of oceans, seas, and continental lakes. Despite significant intensification of paleoclimatic studies in recent years, one can sense a deficit in reliable data on past climates, especially for intracontinental regions of the large Asian continent. Reference data on this region are represented by the results of deep drilling within the framework of the International Baikal‐Hovsgol Drilling Project in the two largest lakes of the Baikal rift zone (Baikal and Hovsgol). Sedimentary sections of these lakes represent a unique continuous record of climatic and environmental changes in Central Asia for a few million years. In terms of detail, the sections are comparable with records obtained from oceanic muds and Greenland and Atlantic ices. However, intracontinental regions can be characterized by significant local climatic variations related to topography and atmospheric circulation. Therefore, we should examine a significantly greater number of objects. The most promising objects for paleoclimatic studies are the present-day systems of small saline lakes, which can exist only in arid and semiarid conditions [1‐3]. These lakes can provide higher resolution records, because they differ from large basins by lesser conservatism relative to the external impacts. Owing to small dimensions, they rapidly respond to any climatic variations. This paper reports the results of study of the evaporate sediments of one small saline lake in the Ol’khon region (western coast of Lake Baikal) with carbonatetype sedimentation. We attempted to reveal natural assemblages of low-temperature carbonates, crystallochemical and structural features of individual carbonate phases, and their formation sequence in lacustrine sediments depending on the past climatic and environmental variations.

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.

Hydrothermal Activity in the Baikal Rift Zone: Recent Hot Springs and Deposits of Paleothermal Waters

ISSN 1028-334X, Doklady Earth Sciences, 2007, Vol. 412, No. 1, pp. 101–105.

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.

Mineralized lakes of the Transbaikalia and Northeastern Mongolia: Specific features of occurrence and ore-generating potential

The paper presents a review of shallow lakes on two neighboring territories, Transbaikalia in Russia and Northeastern Mongolia. Five systems of shallow lakes are distinguished in the regions under study: Barguzin, Eravna-Gusinoozersk, Ingoda, Onon-Borzya, and Eastern-Mongolian systems. The shallow lakes are sub-grouped according to common chemical compositions and geochemical evolution types. Characteristics of ground- and surface waters feeding the lakes are considered. Based on results of trace element analyses of water samples from about 200 lakes and more than 100 springs, wells and boreholes, elements that manifest higher concentrations, resulting from evaporation of lacustrine waters, are determined. Prospects of assessment of ore-generating potential of the shallow lakes as ‘liquid ore’ sources in view of commercial extraction of Li, U, REE, and others metals are discussed.

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�

Baseline levels of chemical elements in the water of Lake Baikal

Evidence for levels of five major elements (Na, Mg, Si, Ca, and K) and 53 trace elements (Li, Be, B,..., Pb, Th, and U) in the water mass of Lake Baikal is provided. The baseline levels of the elements were obtained from analyzing and summarizing the most reliable data published during the last 15 years, including these authors’ data. Most of the article focuses on an overview of the methodologies as used in the investigations involved (sampling techniques, and sample storage, processing and analysis methods). The summary table provides the most reliable concentration ranges for 58 elements which are recommended by these authors as background (baseline) levels.

Geochemical features and fluid conditions of the formation of late quaternary geyserites in the Olkhon area and on Olkhon Island (Baikal rift zone)

In terms of chemical composition, the Late Quaternary geyserites of the Olkhon area and Olkhon Island are subdivided into the ferrosiliceous and carbonate–siliceous groups and are commonly characterized by low concentrations of rare elements. In several cases, the geyserites are enriched in Fe, Mn, Cr, Sb, As, and Y. Regardless of the chemical composition of geyserite, the key components of the gas phase are H2O, CO2, and CH4. The parent matter for the geyserites was constituted by aqueous solutions (fluids) of 400°C and higher temperatures, silica-saturated, and enriched in carbon dioxide and hydrocarbons, as well as in some ore components.