E. G. Vologina

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.

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.

The “methane eruption” on Lake Baikal in 1912 as an effect of a strong earthquake

New factual materials on methane eruptions into the water of Lake Baikal in August 1912 are considered. The regional press is used as the information source. The spatio-temporal relationship between the gas eruptions and earthquakes, observed in South Baikal in 1912, is revealed, which permits us to consider this effect as a consequence of seismic activity intensification. Intensive methane discharge into water is a potential danger for the lake’s ecosystem as was proved by massive death of water organisms in South Baikal in 1912 during the described phenomena.

Reconstruction of the conditions of Late Holocene sedimentation by integrated analysis of a core of the bottom sediments from the Chukchi Sea

Integrated studies were performed on bottom sediments collected in the Chukchi Sea in the northern part of the Gerald Canyon 150 km northeast from Wrangel Island. The recent sedimentation rate amounted to 0.9 mm/year by 210Pb at the sampling site. The concentrations of biogenic components (SiO2bio, Сorg, Ntot, and Br) were minimum at the lower part of the core, where an increase of Thalassiosira antarctica antarctica, probably results from low biological productivity during the Maunder Minimum. The increased concentrations of biogenic components, as well as the decreased values of magnetic susceptibility and X-ray density, in the upper part of the core (1–2 cm) correspond to the last decade of recent of global warming.

Chukchi Sea Ice Conditions for the Last Few Centuries: Reconstruction from Sedimentation Records

For the first time, the reconstruction of variations in the duration over several hundred years was conducted on the basis of models developed by comparing hydrometeorological observations and detailed scanning of the chemical composition of bottom sediments accumulated during the corresponding period. The gauge models for the reconstruction of air temperature and ice cover of the water area for three sites in the northern part of the Chukchi Sea have been developed. During the reconstruction, an insignificant increase in the duration of the ice-free period during the Little Ice Age was established, which does not coincide with the changes in the temperature regime that took place. It is concluded that the dynamics of the inflow of warm Pacific waters through the Bering Strait had the predominant influence on the ice regime of the Chukchi Sea.