(Table 2) Age determination of sediments from lake basins near Polyarny, Russia

A relative sea-level curve for the Holocene is constructed for Polyarny on the Kola Peninsula, northwest Russia. The curve is based on 18 radiocarbon dates of isolation contacts, identified from lithological and diatomological criteria, in nine lake basins situated between 12 and 57 m a.s.l. Most of the lakes show a conformable, regressive I–II–III (marine–transitional–freshwater) facies succession, indicating a postglacial history comprising an early (10,000–9000 radiocarbon years BP) phase of rapid, glacio-isostatically induced emergence (~5 cm/year) and a later phase (after 7000 years BP,) having a moderate rate of emergence (<0.5 cm/year). Three lakes together record a phase of very low rate of emergence or slight sea-level rise at a level of ~27 m a.s.l., between 8500 and 7000 years BP, which correlates with the regional Tapes transgression. Pollen stratigraphy in the highest lake shows that the area was deglaciated before the Younger Dryas and that previously reconstructed Younger Dryas glacier margins along the north Kola coast lie too far nort

Table 1. Radiocarbon dated samples from lake basin cores from the Nikel-Kirkenes area

The marine-lacustrine transition (isolation contact) in sediment cores from eight lake basins situated 13.5–72 m a.s.l., in the Norwegian-Russian border area north of Nikel, northwest Russia, was identified based on lithological and diatom analysis, radiocarbon dated, and used to construct a relative sea-level (RSL) curve for the Holocene. All the lakes except one (interpreted as having an unconformable slumped transition) show a regressive I-II-III (marine-transitional-lacustrine) facies succession, indicating a postglacial history of continuous emergence. The RSL curve shows rapid emergence between 10 000 and 8000 BP, very slow emergence between 7000 and 5000 BP, increased rate of emergence between 4500 and 4000 BP, and a moderate rate of emergence after 3500 BP. The low rate of emergence around 6000 BP correlates with the Tapes transgression of more coastal regions, but corresponding sea level, at 25–26 ma. present s.l., lies 5–10 m lower than the elevation predicted based on existing isobase maps for the region. The discrepancy suggests a need for further work in order to more rigorously define and map the Tapes transgression and associated shoreline complex in the northern Fennoscandian-Kola region

Highly variable sediment deposition in Lake Imandra, NW Russia, since the Late Pleistocene

To understand the dynamics of sediment deposition and the potential influences of complex current systems in large lakes, Lake Imandra (Kola Peninsula) has been investigated. Seismic and echo-sounder data of the central part of Bolshaya Imandra reveal the sediment architecture in unprecedented detail. In addition, the sediment core data indicate highly variable depositional processes since the Late Pleistocene. The complex morphology of the lacustrine basin favoured accumulation of sediment in depressions, where they were preserved from erosion. Three main stratigraphic units (SU I-III) were identified above the acoustic basement. The oldest SU III is best preserved along a tectonic trench and interpreted as glacial deposits partly eroded by the Scandinavian Ice Sheet during Marine Isotope Stage (MIS) 2. The overlying SU II deposits are regarded as a till related to MIS 2 glaciation. The youngest SU I represents glaciofluvial, glaciolacustrine and lacustrine sediment deposited after ice retreat. As the north-south-trending main axis of Bolshaya Imandra runs parallel to the predominant wind direction, the basin is subject to strong wind-induced surficial currents and compensatory subsurface currents. These currents occur in water depth of 0-15 and deeper than 30 m, respectively, and their velocity prevents sediment accumulation

Lateglacial and Holocene environmental history of the central Kola region, northwestern Russia revealed by a sediment succession from Lake Imandra

Bolshaya Imandra, the northern sub-basin of Lake Imandra, was investigated by a hydro-acoustic survey followed by sediment coring down to the acoustic basement. The sediment record was analysed by a combined physical, biogeochemical, sedimentological, granulometrical and micropalaeontological approach to reconstruct the regional climatic and environmental history. Chronological control was obtained by 14C dating, 137Cs, and Hg markers as well as pollen stratigraphy and revealed that the sediment succession offers the first continuous record spanning the Lateglacial and Holocene. Following the deglaciation prior to c. 13 200 cal. a BP, the lake's sub-basin initially was occupied by a glacifluvial river system, before a proglacial lake with glaciolacustrine sedimentation established. Rather mild climate, a sparse vegetation cover and successive retreat of the Scandinavian Ice Sheet (SIS) from the lake catchment characterized the Bølling/Allerød interstadial, lasting until 12 710 cal. a BP. During the subsequent Younger Dryas chronozone, until 11 550 cal. a BP, climate cooling led to a decrease in vegetation cover and a re-advance of the SIS. The SIS disappeared from the catchment at the Holocene transition, but small glaciers persisted in the mountains at the eastern lake shore. During the Early Holocene, until 8400 cal. a BP, sedimentation changed from glaciolacustrine to lacustrine and rising temperatures caused the spread of thermophilous vegetation. The Middle Holocene, until 3700 cal. a BP, comprises the regional Holocene Thermal Maximum (8000–4600 cal. a BP) with relatively stable temperatures, denser vegetation cover and absence of mountain glaciers. Reoccurrence of mountain glaciers during the Late Holocene, until 30 cal. a BP, presumably results from a slight cooling and increased humidity. Since c. 30 cal. a BP Lake Imandra has been strongly influenced by human impact, originating in industrial and mining activities. Our results are in overall agreement with vegetation and climate reconstructions in the Kola region

Lateglacial and Holocene environmental history of the central Kola region, northwestern Russia revealed by a sediment succession from Lake Imandra

Bolshaya Imandra, the northern sub-basin of Lake Imandra, was investigated by a hydro-acoustic survey followed by sediment coring down to the acoustic basement. The sediment record was analysed by a combined physical, biogeochemical, sedimentological, granulometrical and micropalaeontological approach to reconstruct the regional climatic and environmental history. Chronological control was obtained by(14)C dating,Cs-137, and Hg markers as well as pollen stratigraphy and revealed that the sediment succession offers the first continuous record spanning the Lateglacial and Holocene. Following the deglaciation prior toc. 13 200 cal. aBP, the lake's sub-basin initially was occupied by a glacifluvial river system, before a proglacial lake with glaciolacustrine sedimentation established. Rather mild climate, a sparse vegetation cover and successive retreat of the Scandinavian Ice Sheet (SIS) from the lake catchment characterized the Bolling/Allerod interstadial, lasting until 12 710 cal. aBP. During the subsequent Younger Dryas chronozone, until 11 550 cal. aBP, climate cooling led to a decrease in vegetation cover and a re-advance of theSIS. TheSISdisappeared from the catchment at the Holocene transition, but small glaciers persisted in the mountains at the eastern lake shore. During the Early Holocene, until 8400 cal. aBP, sedimentation changed from glaciolacustrine to lacustrine and rising temperatures caused the spread of thermophilous vegetation. The Middle Holocene, until 3700 cal. aBP, comprises the regional Holocene Thermal Maximum (8000-4600 cal. aBP) with relatively stable temperatures, denser vegetation cover and absence of mountain glaciers. Reoccurrence of mountain glaciers during the Late Holocene, until 30 cal. aBP, presumably results from a slight cooling and increased humidity. Sincec. 30 cal. aBPLake Imandra has been strongly influenced by human impact, originating in industrial and mining activities. Our results are in overall agreement with vegetation and climate reconstructions in the Kola region

Multi-proxy data set of the sediment core Co1410 from Lake Imandra, NW Russia

The sediment succession of Lake Imandra in the central Kola region was investigated by a hydro-acoustic survey followed by sediment coring of site Co1410 (67°42'56.76"N, 33°5'6.42"E) down to the acoustic basement. We reconstructed the environmental history of Lake Imandra after the last deglaciation based on physical, biogeochemical, sedimentological, granulometrical, and micropalaeontological proxies. Our findings reveal the timing of the onset of lacustrine sediment deposition in the lake basin during the Late Glacial and the variability of climatic signals throughout the Holocene. All datasets comprise a depth and age column and: 1. S = Sulfur (%); TOC = Total Organic Content (%); TOC/TN = Total Organic Content / Total Nitrogen; Water Content (%); Grain Size d50 (µm); EM1 =Endmember 1 (%); EM2 =Endmember 2 (%); EM3 = Endmember 3 (%) 2. Acroperus harpae; Alona affinis; Alona guttata/Coronatella rectangula; Alona intermedia; Alona quadrangularis; Alona rustica; Alonella excisa; Alonella exigua; Alonella nana; Alonopsis elongata; Bosmina (Bosmina) longirostris; Bosmina (Eubosmina) cf. longispina/cf. coregoni; Chydorus cf. sphaericus; Daphnia longispina agg.; Eurycercus sp. Leptodora kindtii; Monospilus dispar; Paralona pigra; Pleuroxus truncatus; Rhynchotalona falcata; Planktonic; Littoral-benthic ; (%) Acroperus harpae; (%) Alona affinis; (%) Alona guttata/Coronatella rectangula; (%) Alona intermedia; (%) Alona quadrangularis; (%) Alona rustica; (%) Alonella excisa; (%) Alonella exigua; (%) Alonella nana; (%) Alonopsis elongata; (%) Bosmina (Bosmina) longirostris; (%) Bosmina (Eubosmina) cf. longispina/cf. coregoni; (%) Chydorus cf. sphaericus; (%) Daphnia longispina agg.; (%) Eurycercus sp.; (%) Leptodora kindtii; (%) Monospilus dispar; (%) Paralona pigra; (%) Pleuroxus truncatus; (%) Rhynchotalona falcata 3. magnetic susceptibility (SI * 10^-5) 4. Pinus(%); Artemisia (%); Total Pollen Concentration /1000; AP/NAP; Arboreale Pollen (%); Non-Arboreale Pollen (%) 5. Zr/Rb (log); Rb/Sr; Zr/Al; K/Al; Ti (cps); Ti/Al; Si (cps); Si/Ti; Br/Al; Fe (cps); Fe/M