Detailed Holocene climate record from the carbonate section of saline Lake Tsagan-Tyrm (West Baikal area)

Abstract

We present results of a complex study of evaporite sediments from one of the small saline lakes with carbonate sedimentation in the Ol’khon area and substantiate their high significance for paleoclimatic reconstructions. The mineral composition of the bottom sediments was studied by XRD analysis, IR spectroscopy, scanning electron microscopy, elemental analysis (SR-XFA), etc. By decomposition of the complex XRD profiles of carbonate minerals into individual peaks by Pearson VII function, we identified carbonate phases in each sample and determined their proportions. A high-resolution carbonate record has been obtained for the first time for the lacustrine sediments. It bears the information about the stratigraphic distribution of Mg-calcites (a continuous series of structurally disordered low- to high-Mg calcites, up to Ca-dolomites), in which the amount and proportions of phases with different Mg contents are controlled by Mg/Ca, salinity, and total alkalinity of the lake water changing depending on the climatic cycles and lake level fluctuations. Comparison of the carbonate record for the Holocene section dated by the radiocarbon (14C) method with results of lithological, diatom, and palynological analyses, data on stable isotopes (δ18O and δ13C), and the distribution of some geochemical indicators of climatic changes permitted the reconstruction of the intricate evolution of the Lake Tsagan-Tyrm basin, which was controlled by the regional climate from the Atlantic period to the present time. The directed change in various characteristics of essentially carbonate sediments evidences that the Ol’khon regional climate has become more arid in recent 6.5 kyr. Moreover, drastic frequent changes of climate and, correspondingly, the Lake Tsagan-Tyrm water level in different periods of its existence have been revealed. The widespread saline and brackish lakes in southern East Siberia, Mongolia, and North China and the highly informative (in terms of paleoclimate and paleolimnology) carbonate sediments might help to recognize the general tendencies of paleoclimate changes and local fluctuations in Central Asia.

Oxygen isotope composition of diatoms from sediments of Lake Kotokel (Buryatia)

“…Lithology, mineralogy, and chemistry of bottom sediments have important implications for the history of lakes, sediment provenance, and responses of lake systems to global change (Sklyarov et al, 2010;Kuzmin et al, 2014). Variations in oxygen isotope composition (δ 18 O) of limnic fossils found in sediments, such as foraminifera, ostracods, or gastropods, bear imprint of their environments and can be used as a climate proxy (Faure, 1986).…”

“…According to interdisciplinary results (Bezrukova et al, 2010;Müller et al, 2010Müller et al, , 2014Sklyarov et al, 2010), bottom sediments of small lakes furnish valuable information for reconstructions of Late Pleistocene climates and environments on different scales. Specifically, the ecosystem of Lake Kotokel located at the taiga/steppe boundary ( Fig.…”

The last glacial maximum and late glacial environmental and climate dynamics in the Baikal region inferred from an oxygen isotope record of lacustrine diatom silica

“…1a) located far from oceanic influences is one of the world's most sensitive regions to abrupt climate shifts and multimillennial variability (Prokopenko et al, 2001;Mackay, 2007;Tarasov et al, 2007;Kuzmin et al, 2009;Sklyarov et al, 2010;Shichi et al, 2013). To date, the last and late glacial climate and environment development history in the region was primarily reconstructed based on multi-proxy data from Lake Baikal (Prokopenko et al, 2001;Karabanov et al, 2004;Bo€ es et al, 2005;Demske et al, 2005;Morley et al, 2005;Mackay, 2007;Kuzmin et al, 2009;Mackay et al, 2011) and using pollen and diatom records from the relatively small (about 69 km 2 ) and shallow (about 4 m mean water depth) Lake Kotokel ) located near Lake Baikal ( Fig.…”

Characterization of modern dolomite stromatolites from hypersaline Petukhovskoe Soda Lake, Russia

“…Cryptocrystalline silica species, including opal, can represent a mixture of α ‐quartz, α ‐cristobalite and α ‐tridymite with a noticeable presence of molecular water (Sklyarov et al . ).…”