Elena V. Bezrukova

The Lake Baikal drilling project in the context of a global lake drilling initiative

Abstract Records of the tectonic and climatic evolution of continental interiors are important for understanding the dynamics of the Earths climate system, evolutionary processes within the terrestrial biosphere, and human origins. Sediment drill cores recovered from Lake Baikal provide essential records not only for comparison with oceanic records of marine processes, but also benchmarks which can be used to help interpret other continental records including other lake archives scheduled to be drilled in the near future. Drilling of Lake Baikal made it possible for the first time to have a continental archive with the same scientific and chronostratigraphic integrity as marine records to address critical questions of the Quaternary and Pliocene. The Lake Baikal drilling project (BDP) rapidly progressed from piston coring and seismic reflection studies to conducting the first scientific drilling in 4 short years and to very deep drilling in over 8 years. BDP has taken advantage of the harsh Siberian winters by using the frozen surface of Lake Baikal as a drilling platform. The positioning of the drill sites was selected using seismic and piston coring surveys. By continuously improving the drilling operations and technology, BDP has achieved new core recovery and depth records over the last ten years and become the worlds leader in pioneering the recovery of high-quality, extremely long lacustrine sediment sequences from deep water. The success of BDP came at a time of growing interest in lake drilling among members of the paleoclimate community with few recent large-scale coordination efforts to draw upon. At the organizational, technological and financial levels, some recent changes are favorable for the development of a global lake drilling initiative, which could become as successful and efficient as the ocean drilling program.

Radiocarbon chronology of the late Pleistocene-Holocene paleogeographic events in lake Baikal region (Siberia)

New radiocarbon dates obtained from Late Pleistocene and Holocene deposits of the southern, eastern, and northern shores of Lake Baikal in 1995-2001 are presented, and the most important results of paleoenvironmental studies based on (super 14) C data are discussed. The following paleogeographic events were verified with the help of (super 14) C dating: 1) first Late Pleistocene glaciation (Early Zyryan); 2) Middle Zyryan interstadial; 3) loess formation during the Late Zyryan (Sartan) deglaciation; 4) warm and cold events in the Late Glacial; and 5) vegetation changes and forest successions during the Late Glacial and Holocene.

Pollen Record from the Chivyrkui Bay Outcrop on the Eastern Shore of Lake Baikal since the Late Glacial

Bogs have formed on the shore of Chivyrkui Bay near Svyatoy Nose Peninsula on the eastern shore of Lake Baikal. Two sediment columns were taken from the outcrop of one of bogs (53°39′N, 109°12′E) to investigate the vegetation history of the eastern shore area of Lake Baikal. The forests around the bog are composed mainly of Pinus sylvestris, Pinus sibirica, Larix sibirica, and Abies sibirica. The results of a palynological study of the cores with 14 radio-carbon dates revealed the following vegetation history since the late glacial. The late glacial and early Holocene vegetation from 12000 to 9000 14C years BP was a shrub tundra with spruce and birch trees, thickets of dwarf birch and alder, and herbs such as Gramineae and Artemisia. Between 9000 and 8000 14C years BP, spruce forests expanded in the area, accompanied by some fir and pine, indicating the initial development of the dark taiga. Pine trees gradually increased after 8000 14C years BP and then started a dramatic increase, to become dominant in 6000 14C years BP in the dark taiga forests. The vegetation from 6000 14C years BP to the present was mainly composed of pines (Pinus sylvestris and P. sibirica) and birch, accompanied by spruce, fir, and larch.

Lake Hovsgol in the Late Pleistocene and Holocene: On-Land Geological Evidence for a Change in Its Level

We present geomorphological and sedimentological evidence for a change in the level of Lake Hovsgol during the second half of the late Pleistocene and Holocene. Both transgressive and regressive stages of lake evolution have been deduced from a study of lacustrine, river, slope, and glacial sediments and landforms. The events which caused the lake level to rise took place in the Karginian,* late Sartanian, early Holocene, and recent time, and were a result of warming periods. The lowering of the level resulted from periods of glaciation and the middle Holocene arid stage.

High‐Resolution Mis 11 Record from the Continental Sedimentary Archive of Lake Baikal

The sedimentary record of Lake Baikal reveals details about the climatic response of continental Asia during the interval 423-362 Ka BP, corresponding to marine oxygen isotope stage MIS 11. The MIS 11 record in Lake Baikal is marked by two plateaus of high biogenic silica content corresponding to MIS 11.3 and 11.2. The middle part of MIS 11 (substage 11.2) exhibits the highest biogenic silica accumulation, reflecting the warmest regional climate, of the last 450 Ka. These interglacial conditions in continental Asia were uninterrupted for about 32 Ka, making MIS 11 the longest interglacial in Siberia, greatly exceeding the duration of interglacial conditions during MIS 5e, 7e and 9e. This extremely long and warm interglacial period of MIS 11.3-11.2 in Siberia ended abruptly with dramatic cooling at 394-390 Ka BP. This cooling resulted in brief mountain glaciation in Siberia due to the amplified response of continental Asia to insolation forcing. The cooling during MIS 11 produced irreversible change in the climate of continental Asia as suggested by diatom succession and by biogenic silica accumulation. Diatom species composition further reveals more complex structure of MIS 11 and makes a strong case for insolation control of diatom production in Lake Baikal.

Glaciations of central asia in the late cenozoic according to the sedimentary record from lake baikal

Publisher Summary This chapter describes the paleoclimatic record over the period of 5 million years based on variations in diatom abundance in the sediments of a 200 m core obtained from Lake Baikal. The data represent a long, continuous continental record of climate changes in Central Asia during the Late Cenozoic. The record shows the climatic cooling trend that started in Pleistocene and is superimposed on the short-term cyclic climatic variations controlled by the Earths orbital parameters. The record also reveals the presence of the two cold episodes (each about 300 Ka long) at the time intervals 2.82–2.48 Ma and 1.75–1.45 Ma characterized by glaciations at their maximum phases. These cooling periods in Lake Baikal record are also registered as global cooling in other paleoclimate records of the Northern Hemisphere. The continental record of Lake Baikal contains the majority of climatic events found in marine records and demonstrates that continental regions of Asia responded to all major changes in the Earths climate recorded in the long oxygen isotopic records.

Pliocene-Quaternary Vegetation and Climate History of the Lake Baikal Area, Eastern Siberia

A palynological study was carried out on the BDP-96 hole 1 core. We distinguished six major large stages (Al-6) characterized by vegetation changes in the Lake Baikal catchment area. The existence of the most abundant amount of pollen, Tsuga, is a specific feature of the pollen spectra of stage A6 from 3.1 to 2.6Ma.The pollen complex of dark coniferous arboreal plants such as Tsuga, Abies, and Picea, which are sensitive to air humidity, serves as an indicator of the amelioration of climatic conditions. There is a process of replacement of Tsuga pollen by Abies in the pollen spectra of stage A5. The age of this stage was determined to be from 2.6 to 2.35Ma. These are the first reliable palaeobotanical data obtained from continuous cross sections, which reflect the response of regional vegetation and flora to the first well-known significant cooling in the northern hemisphere—the Praetiglian. During stage A4 larch appears and is widely distributed. This is probably connected with the start of a temporary cold continental, climate. At the beginning of stage A3, about 1.85Ma, a new amelioration of climatic conditions takes place. The beginning of stage A2, about 1.5Ma, was characterized by an abrupt change in the composition of regional vegetation and flora. Tsuga disappears from the flora composition, and Larix and Betula are again widely distributed. Pinus pumila appears, and continues to exist. During stage Al, vegetation which was similar to that of the present started to persist in the region, and the climate became sharply continental, and moderately cold

First data on the environment and climate change within the Zhom-Bolok volcanic field (Eastern Sayan Mountains) in the Middle–Late Holocene

This paper considers the results of comprehensive lithological, biostratigraphic, and geochemical investigation of sediments in Khara-Nur Lake (Eastern Sayan Mountains) situated in the area of the greatest Holocene eruptions in the Central Asia Region. The age of the basal sediment layer is estimated at 6881 ± 53 years. The local natural environment and climate have undergone great changes since that time. The Holocene volcanic events did not exert a catastrophic impact on the regional landscape, but they caused dramatic changes in the local vegetation. The well-defined correlation of the regional events with the well-known records of the natural environment in the Northern Hemisphere is indicative of the decisive influence of global atmospheric circulation on restructuring the landscape and climate system in the Zhom-Bolok Region in the Middle–Late Holocene.

Reconstruction of the Holocene Climate of Transbaikalia: Evidence from the Oxygen Isotope Analysis of Fossil Diatoms from Kotokel Lake

Fossil diatoms or Bacillariophyta are microscopicunicellular organisms with siliceous cell–frustule consisting of two separate valves that play an importantrole in marine and lake sedimentation. The data ofdiatom analysis provide reliable spatial and temporalreconstructions of the natural environment and theclimate of past geological epochs [1].The possibility of investigation of fossil Bacillariophyta by the oxygen isotope method in order to obtainpaleoinformation was originally demonstrated by L.Labeyrie [2]. The plotted isotope curves indicate variations in the temperature and isotope composition ofwater (δ

New Data on Environments of Cisbaikalia in the Late Holocene

New data on changes in late Holocene environments of Cisbaikalia have been obtained based on integrated studies of the mode of occurrence, genetic types, stratigraphy, and data on absolute geochronology and morphology, as well as palynological, chemical, and grain size compositions of paragenetically related loose sediments of key sections in the central part of the western coast of Lake Baikal. The sections are located in piedmont‐saddle (the Bezymyannyi section) and floodplain‐valley (the Kuchelga section) geomorphological conditions (Fig. 1). Environments of the Subboreal and Subatlantic intervals of the Holocene were reconstructed based on the analysis of loose sediments of the Bezymyannyi section. The section is located in the water-logged, birch‐willow, underbrush (dogrose and currant), and moss‐sedge forest in the subaqueous (high floodplain) area between the Kuchelga River channel and the Bezymyannyi Creek at the foothill of the Primorskii Range. The forest is surrounded by petrophyte thin larch forest with stepped herbs and undergrowth (spiraea and cotoneaster), birch, and aspen. The section is located at the foothill‐saddle surface (slope 1°–3° ) characterized by the minimum influence of gravitational agents of morphogenesis. The basic results of the study of loose sediments in this section are presented below. The total thickness of the section is 95 cm. Mineralized peat deposits occur down to the depth of 42 cm. A fragment of a buried cedar trunk was found at a depth of 22‐32 cm. Five radiocarbon ages have been obtained for this part of the section (table). Interval 78‐95 cm. Sediments of this interval accumulated under hydrogeodynamic conditions with a stable regime of atmospheric precipitation, which afforded sand deposition and brought debris of medium roundness during snow melting, indicating a constancy of water flow. Such conditions seem to be typical for the end of the Atlantic interval of the Holocene. We failed to reconstruct paleovegetation due to the lack of pollen in this bed, probably because of the large size of sand grains in this bed (as compared to spore-and-pollen) and their consequent removal.