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

Abstract

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.