Ice-free conditions in eastern Fennoscandia during early Marine Isotope Stage 3 : lacustrine records

• The traditional notion that Fennoscandia was glaciated throughout Marine Isotope Stages (MIS) 4-2, from c. 70 kyr BP to the deglaciation 15-10 kyr BP ago, has been challenged during the last decade. Recent studies have shown that climate and environmental settings during MIS 3 were more dynamic than previously assumed, and lacustrine sediment bodies indicate open-water conditions for several sites in eastern Fennoscandia. In this study, three sediment sequences from western, eastern and northeast Finland are compared in detail with respect to their chronology, vegetation reconstruction and climatic inferences. OSL-dating places the sediments in early MIS 3. Pollen evidence suggests the presence of isolated birch trees and open birch forest close to the retreating ice margin, in contrast to vegetation reconstructions from central Europe, which indicate tree-less vegetation. Furthermore, reconstructions of climate using transfer functions have yielded surprising results, indicating present-day summer temperatures in northeast Finland. The combined results suggest ice-free and warm conditions in major parts of eastern Fennoscandia in early MIS 3, possibly during Greenland Interstadial (GIS) 14 around 53 kyr BP ago.

Keyword

NATURAL SCIENCES

NATURVETENSKAP

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ref (subject category)

art (subject category)