PALAEORUNOFF FROM LAKE LADOGA TO THE BALTIC SEA DURING THE HOLOCENE

The article presents the results of the palaeohydrological analysis of the river system reorganization in the North-West of Russia, the Karelian Isthmus. This study aimed at the hydrological calculation of the runoff through the Heinjoki water connection of Lake Ladoga, the Gulf of Finland and PalaeoVuoksa during different periods of the Holocene. The methods of the equation of water balance, hydraulic-morphometric dependencies and the method of geographical analogy were used in this research. The main result of the carried work is the refinement of the existing regional flow model. In particular, the role of the Heinjoki Strait and the Neva River channel in different stages of the Holocene is considered. The authors came to the conclusion that Lake Ladoga always had a runoff to the Baltic Sea. It is shown that most probably in the period of 10,200-3,500 years ago the runoff was carried out through the Heinjoki waterway. The study underlines that the isostatic factor played a significant role in the forming of the water flow. The change in the runoff direction from the Heinjoki waterway to the Neva River is mainly related to the isostatic uplift of the Karelian Isthmus and the northern part of Lake Ladoga. Quantitative parameters of the Heinjoki palaeoflow (flow rate, annual runoff, runoff layer, runoff coefficient) seem to be roughly equivalent to the modern parameters of the flow of the Neva River. The article is dedicated to our colleague, a talented geographer and teacher, PhD Oleg Borisovich Averichkin (1979-2010) who first performed the calculations of the paleorunoff of Lake LadogaThe article presents the results of the palaeohydrological analysis of the river system reorganization in the North-West of Russia, the Karelian Isthmus. This study aimed at the hydrological calculation of the runoff through the Heinjoki water connection of Lake Ladoga, the Gulf of Finland and PalaeoVuoksa during different periods of the Holocene. The methods of the equation of water balance, hydraulic-morphometric dependencies and the method of geographical analogy were used in this research. The main result of the carried work is the refinement of the existing regional flow model. In particular, the role of the Heinjoki Strait and the Neva River channel in different stages of the Holocene is considered. The authors came to the conclusion that Lake Ladoga always had a runoff to the Baltic Sea. It is shown that most probably in the period of 10,200-3,500 years ago the runoff was carried out through the Heinjoki waterway. The study underlines that the isostatic factor played a significant role in the forming of the water flow. The change in the runoff direction from the Heinjoki waterway to the Neva River is mainly related to the isostatic uplift of the Karelian Isthmus and the northern part of Lake Ladoga. Quantitative parameters of the Heinjoki palaeoflow (flow rate, annual runoff, runoff layer, runoff coefficient) seem to be roughly equivalent to the modern parameters of the flow of the Neva River. The article is dedicated to our colleague, a talented geographer and teacher, PhD Oleg Borisovich Averichkin (1979-2010) who first performed the calculations of the paleorunoff of Lake Ladog

In search for fingerprints of an extraterrestrial event: Trace element characteristics of sediments from the lake Medvedevskoye (Karelian Isthmus, Russia)

Concentration and distribution of trace elements across the sequence of the Late Pleistocene sediments from the lake Medvedevskoye suggest the addition of materials other than those from a common source for the lake sediments of the region. The sediments of the lake Medvedevskoye carry some geochemical fingerprints which could be related the ET event that occurred at ca. 12.9 ka. Because such fingerprints are extremely subtle, the NW Russia can be considered to be the most remote eastern region of the extent of the Late Pleistocene airborne ET material. The sediments of the lake Medvedevskoye can also contain volcanic material from the eruption of the Laacher See (Germany) volcano and probably from other Late Pleistocene volcanoes of Western Europe and/or Iceland. © 2014 Pleiades Publishing, Ltd

Paleolimnological studies in Russian northern Eurasia: A review

© 2017, Pleiades Publishing, Ltd. This article presents a review of the current data on the level of paleolimnological knowledge about lakes in the Russian part of the northern Eurasia. The results of investigation of the northwestern European part of Russia as the best paleolimnologically studied sector of the Russian north is presented in detail. The conditions of lacustrine sedimentation at the boundary between the Late Pleistocene and Holocene and the role of different external factors in formation of their chemical composition, including active volcanic activity and possible large meteorite impacts, are also discussed. The results of major paleoclimatic and paleoecological reconstructions in northern Siberia are presented. Particular attention is given to the databases of abiotic and biotic parameters of lake ecosystems as an important basis for quantitative reconstructions of climatic and ecological changes in the Late Pleistocene and Holocene. Keywords: paleolimnology, lakes, bottom sediments, northern

Northern Eurasian large lakes history: sediment records obtained in the frame of Russian-German research project PLOT

Russian-German project PLOT (Paleolimnological Transect) aims at investigating the regional responses of the quaternary climate and environment on external forcing and feedback mechanisms along a more than 6000 km long longitudinal transect crossing Northern Eurasia. The well-dated record from Lake El´gygytgyn used as reference site for comparison the local climatic and environmental histories. Seismic surveys and sediment coring up to 54 m below lake floor performed in the frame of the project on Ladoga Lake (North-West of Russia; 2013), Lake Bolshoye Shchuchye (Polar Ural; 2016), Lake Levinson-Lessing and Lake Taymyr (Taymyr Peninsula; 2016-2017), Lake Emanda (Verkhoyansk Range; 2017). Fieldwork at Polar Ural and Taymyr Peninsula was conducted in collaboration with the Russian-Norwegian CHASE (Climate History along the Arctic Seaboard of Eurasia) project. Here, we present the major results of the project obtained so far

Late Quaternary vegetation and lake system dynamics in north-eastern Siberia: Implications for seasonal climate variability

© 2015 Elsevier Ltd. Although the climate development over the Holocene in the Northern Hemisphere is well known, palaeolimnological climate reconstructions reveal spatiotemporal variability in northern Eurasia. Here we present a multi-proxy study from north-eastern Siberia combining sediment geochemistry, and diatom and pollen data from lake-sediment cores covering the last 38,000cal. years. Our results show major changes in pyrite content and fragilarioid diatom species distributions, indicating prolonged seasonal lake-ice cover between ~13,500 and ~8900cal. years BP and possibly during the 8200cal. years BP cold event. A pollen-based climate reconstruction generated a mean July temperature of 17.8°C during the Holocene Thermal Maximum (HTM) between ~8900 and ~4500cal. years BP. Naviculoid diatoms appear in the late Holocene indicating a shortening of the seasonal ice cover that continues today. Our results reveal a strong correlation between the applied terrestrial and aquatic indicators and natural seasonal climate dynamics in the Holocene. Planktonic diatoms show a strong response to changes in the lake ecosystem due to recent climate warming in the Anthropocene.We assess other palaeolimnological studies to infer the spatiotemporal pattern of the HTM and affirm that the timing of its onset, a difference of up to 3000 years from north to south, can be well explained by climatic teleconnections. The westerlies brought cold air to this part of Siberia until the Laurentide ice-sheet vanished 7000 years ago. The apparent delayed ending of the HTM in the central Siberian record can be ascribed to the exceedance of ecological thresholds trailing behind increases in winter temperatures and decreases in contrast in insolation between seasons during the mid to late Holocene as well as lacking differentiation between summer and winter trends in paleolimnological reconstructions

Late Quaternary vegetation and lake system dynamics in north-eastern Siberia: Implications for seasonal climate variability

© 2015 Elsevier LtdAlthough the climate development over the Holocene in the Northern Hemisphere is well known, palaeolimnological climate reconstructions reveal spatiotemporal variability in northern Eurasia. Here we present a multi-proxy study from north-eastern Siberia combining sediment geochemistry, and diatom and pollen data from lake-sediment cores covering the last 38,000 cal. years. Our results show major changes in pyrite content and fragilarioid diatom species distributions, indicating prolonged seasonal lake-ice cover between ∼13,500 and ∼8900 cal. years BP and possibly during the 8200 cal. years BP cold event. A pollen-based climate reconstruction generated a mean July temperature of 17.8 °C during the Holocene Thermal Maximum (HTM) between ∼8900 and ∼4500 cal. years BP. Naviculoid diatoms appear in the late Holocene indicating a shortening of the seasonal ice cover that continues today. Our results reveal a strong correlation between the applied terrestrial and aquatic indicators and natural seasonal climate dynamics in the Holocene. Planktonic diatoms show a strong response to changes in the lake ecosystem due to recent climate warming in the Anthropocene. We assess other palaeolimnological studies to infer the spatiotemporal pattern of the HTM and affirm that the timing of its onset, a difference of up to 3000 years from north to south, can be well explained by climatic teleconnections. The westerlies brought cold air to this part of Siberia until the Laurentide ice-sheet vanished 7000 years ago. The apparent delayed ending of the HTM in the central Siberian record can be ascribed to the exceedance of ecological thresholds trailing behind increases in winter temperatures and decreases in contrast in insolation between seasons during the mid to late Holocene as well as lacking differentiation between summer and winter trends in paleolimnological reconstructions

Arctic Holocene proxy climate database – New approaches to assessing geochronological accuracy and encoding climate variables

We present a systematic compilation of previously published Holocene proxy climate records from the Arctic. We identified 170 sites from north of 58° N latitude where proxy time series extend back at least to 6 cal ka (all ages in this article are in calendar years before present - BP), are resolved at submillennial scale (at least one value every 400 ± 200 years) and have age models constrained by at least one age every 3000 years. In addition to conventional metadata for each proxy record (location, proxy type, reference), we include two novel parameters that add functionality to the database. First, "climate interpretation" is a series of fields that logically describe the specific climate variable(s) represented by the proxy record. It encodes the proxy-climate relation reported by authors of the original studies into a structured format to facilitate comparison with climate model outputs. Second, "geochronology accuracy score" (chron score) is a numerical rating that reflects the overall accuracy of 14C-based age models from lake and marine sediments. Chron scores were calculated using the original author-reported 14C ages, which are included in this database. The database contains 320 records (some sites include multiple records) from six regions covering the circumpolar Arctic: Fennoscandia is the most densely sampled region (31% of the records), whereas only five records from the Russian Arctic met the criteria for inclusion. The database contains proxy records from lake sediment (60%), marine sediment (32%), glacier ice (5%), and other sources. Most (61%) reflect temperature (mainly summer warmth) and are primarily based on pollen, chironomid, or diatom assemblages. Many (15%) reflect some aspect of hydroclimate as inferred from changes in stable isotopes, pollen and diatom assemblages, humification index in peat, and changes in equilibrium-line altitude of glaciers. This comprehensive database can be used in future studies to investigate the spatio-temporal pattern of Arctic Holocene climate changes and their causes. The Arctic Holocene data set is available from NOAA Paleoclimatology. © Author(s) 2014