TY - JOUR A1 - Hoff, Ulrike A1 - Biskaborn, Boris A1 - Dirksen, Veronika G. A1 - Dirksen, Oleg A1 - Kuhn, Gerhard A1 - Meyer, Hanno A1 - Nazarova, Larisa B. A1 - Roth, Alexandra A1 - Diekmann, Bernhard T1 - Holocene environment of Central Kamchatka, Russia: Implications from a multi-proxy record of Two-Yurts Lake JF - Global and planetary change N2 - Within the scope of Russian German palaeoenvironmental research, Two-Yurts Lake (TYL, Dvuh-Yurtochnoe in Russian) was chosen as the main scientific target area to decipher Holocene climate variability on Kamchatka. The 5 x 2 km large and 26 m deep lake is of proglacial origin and situated on the eastern flank of Sredinny Ridge at the northwestern end of the Central Kamchatka Valley, outside the direct influence of active volcanism. Here, we present results of a multi-proxy study on sediment cores, spanning about the last 7000 years. The general tenor of the TYL record is an increase in continentality and winter snow cover in conjunction with a decrease in temperature, humidity, and biological productivity after 5000-4500 cal yrs BP, inferred from pollen and diatom data and the isotopic composition of organic carbon. The TYL proxy data also show that the late Holocene was punctuated by two colder spells, roughly between 4500 and 3500 cal yrs BP and between 1000 and 200 cal yrs BP, as local expressions of the Neoglacial and Little Ice Age, respectively. These environmental changes can be regarded as direct and indirect responses to climate change, as also demonstrated by other records in the regional terrestrial and marine realm. Long-term climate deterioration was driven by decreasing insolation, while the short-term climate excursions are best explained by local climatic processes. The latter affect the configuration of atmospheric pressure systems that control the sources as well as the temperature and moisture of air masses reaching Kamchatka. (C) 2015 Elsevier B.V. All rights reserved. KW - Kamchatka KW - North Pacific KW - Holocene Climate KW - Palaeolimnology KW - Diatoms KW - Pollen Y1 - 2015 U6 - https://doi.org/10.1016/j.gloplacha.2015.07.011 SN - 0921-8181 SN - 1872-6364 VL - 134 SP - 101 EP - 117 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nazarova, Larisa B. A1 - Bleibtreu, Annette A1 - Hoff, Ulrike A1 - Dirksen, Veronika A1 - Diekmann, Bernhard T1 - Changes in temperature and water depth of a small mountain lake during the past 3000 years in Central Kamchatka reflected by a chironomid record JF - Quaternary international : the journal of the International Union for Quaternary Research N2 - We investigated chironomid assemblages of a well-dated sediment core from a small seepage lake situated at the eastern slope of the Central Kamchatka Mountain Chain, Far East Russia. The chironomid fauna of the investigated Sigrid Lake is dominated by littoral taxa that are sensitive to fluctuations of the water level. Two groups of taxa interchangeably dominate the record responding to the changes in the lake environment during the past 2800 years. The first group of littoral phytophilic taxa includes Psectrocladius sordidellus-type, Corynoneura arctica-type and Dicrotendipes nervosus-type. The abundances of the taxa from this group have the strongest influence on the variations of PCA 1, and these taxa mostly correspond to low water levels, moderate temperatures and slightly acidified conditions. The second group of taxa includes Microtendipes pedellus-type, Tanytarsus lugens-type, and Tanytarsus pallidicornistype. The variations in the abundances of these taxa, and especially of M. pedellus-type, are in accordance with PCA 2 and correspond to the higher water level in the lake, more oligotrophic and neutral pH conditions. Water depths (WD) were reconstructed, using a modern chironomid-based temperature and water depth calibration data set (training set) and inference model from East Siberia (Nazarova et al., 2011). Mean July air temperatures (T July) were inferred using a chironomid-based temperature inference model based on a modern calibration data set for the Far East (Nazarova et al., 2015). The application of transfer functions resulted in reconstructed T July fluctuations of approximately 3 degrees C over the last 2800 years. Low temperatures (11.0-12.0 degrees C) were reconstructed for the periods between ca 1700 and 1500 cal yr BP (corresponding to the Kofun cold stage) and between ca 1200 and 150 cal yr BP (partly corresponding to the Little Ice Age [LIA]). Warm periods (modern T July or higher) were reconstructed for the periods between ca 2700 and 1800 cal yr BP, 1500 and 1300 cal yr BP and after 150 cal yr BP. WD reconstruction revealed that the lake level was lower than its present level at the beginning of the record between ca 2600 and 2300 cal yr BP and ca 550 cal yr BP. Between ca 2300 and 700 cal yr BP as well as between 450 and 150 cal yr BP, the lake level was higher than it is today, most probably reflecting more humid conditions. (C) 2016 Elsevier Ltd and INQUA. All rights reserved. KW - Kamchatka KW - Chironomids KW - Palaeoclimate KW - Late Holocene KW - Temperature KW - Water depth Y1 - 2017 U6 - https://doi.org/10.1016/j.quaint.2016.10.008 SN - 1040-6182 SN - 1873-4553 VL - 447 SP - 46 EP - 58 PB - Elsevier CY - Oxford ER -