Unstable early-Holocene climatic and environmental conditions in northwestern Russia derived from a multidisciplinary study of a lake-sediment sequence from Pichozero, southeastern Russian Karelia

Abstract

A HOLOCENE RESEARCH PAPER Abstract: A sediment core from Lake Pichozero (61°46'; N, 37°25'; E 118 m a.s.l.) provides information on the environmental and climatic conditions in southeastern Russian Karelia during the Lateglacial and early Holocene (12 800-9300 cal. BP). The chronology of the sequence is constrainied by varve counting and AMS 14C measurement of terrestrial plant macrofossils. Multiproxy analyses (magnetic susceptibility, grain size, TOC, TN, TS, Rock Eval, pollen and macrofossils) imply that cold and dry regional climatic conditions with sparse Arctic vegetation prevailed prior to 11500 cal. BP. Coincident with the transition to the Holocene at 11 500 cal.BP, air temperatures and lake productivity increased and Betula pubescens and Populus treinula started to migrate into the area, followed by Picea abies at 10 750 cal. BP. Although lake productivity decreased at around 11 000 cal. BP and remained low until 9600 cal. BP, pollen-based climate reconstructions imply variable climatic conditions in the region over time. Drier and colder summers prevailed from 11200 to 10900 cal. BP, followed by an interval of higher annual temperatures and precipitation from 10900 to 10750 cal. BP. Lower annual temperatures and drier conditions existed from 10750 to 10200 cal. BP, and higher temperatures and precipitation are inferred between 10200 and 10000 cal. BP. Finally, declining temperatures and precipitation occurred from 10 000 cal. BP onwards, with a minimum at around 9600 cal. BP. These climatic shifts are temporally coincident with those recorded in North Atlantic terrestrial, marine and ice-core archives and indicate that relatively minor climate signals were transmitted further to the east.

Deglaciation history of Lake Ladoga (northwestern Russia) based on varved sediments

“…Low meltwater supply was probably due to low temperatures, as suggested by regional pollen-based climate reconstructions (Subetto et al 2002;Wohlfarth et al 2004) as well as ice-core data (e.g. ka BP.…”

Rapid Lateglacial tree population dynamics and ecosystem changes in the eastern Baltic region

“…Permafrost affected the land and soils as far south as $548 N and evidence for periglacial phenomena is found to $508 N (Isarin, 1997). At the end of the YD mean July temperatures rose 4-108C Wohlfarth et al, 2004).…”

The last Scandinavian Ice Sheet in northwestern Russia: ice flow patterns and decay dynamics

“…The age of the oldest organic remnants in sediments from lakes across the downwasting zone belongs to the Allerød interstadial (Ekman & Iljin 1995;Davydova et al 1998). Deposition of organic debris in small lakes on the watersheds covered by dead ice began as late as the Preboreal and Boreal Wohlfarth et al 2002Wohlfarth et al , 2004. Huge areas in the peripheral parts of the SIS therefore stagnated rapidly, fields of debris-covered dead ice spent 4Á7 kyr of degradation as the climate was cold and permafrost still prevailed and because thick overburden retarded heat transfer, thereby delaying downwasting.…”

“…The sub-arctic flora arrived in the region at the beginning of the Allerød period (Baranovskaya et al 1977;Wohlfarth et al 2002Wohlfarth et al , 2004, while buried glacier ice was melting causing inversion of the landscape, as was also the case in the area northeast of the Arkhangelsk district which was covered by an older Weichselian ice sheet from the BarentsÁKara Seas (Tveranger et al 1995). From the eastern North Sea across the southern Baltic to northwest Russia, Late Weichselian streamlined terrains separated by belts of terminal moraines possibly generated by narrow and rapidly flowing ice lobes are overprinted by landforms that relate to aerial downwasting (cf.…”