Ice-free intervals continuing into Marine Isotope Stage 3 at Sokli in the central area of the Fennoscandian glaciations

Abstract

An unusually long and continuous Late Quaternary sedimentary sequence has been preserved in a sedimentary basin formed in the Sokli Carbonatite Massif in eastern-central Finnish Lapland. A nearly complete sediment recovery from the central Sokli basin combined with palynological results from sediments not earlier recovered and an independent OSL/AMS 14 C chronology allow us here to define the Late Quaternary climate-stratigra phy at Sokli and describe in detail the environmental record. Three interstadial intervals of Weichselian age are distinguished that correlate with MIS 5c, 5a and part of MIS 3 in the marine oxygen-isotope record. The interstadials of MIS 5c and 3 age are here defined as the Sokli and Tulppio Interstadials, respectively. The MIS 5a interstadial is correlated with the Maaselka/Perapohjola Interstadials of Finnish Lapland, which previously have been tentatively assigned a MIS 5c age. Till beds in the Sokli sequence (deposited during stadials 3– 1) correlate to MIS 5b, 4 and 3/2, respectively. Depositional environments and vegetational changes during the ice-free intervals at Sokli are discussed. The Sokli sedimentary sequence indicates significantly less extensive and more variable ice-cover over Finnish Lapland dur ing the Weichselian than has been earlier suggested based on the long-distance correlation of litho- and bio-stratigraphic fragmentary evidence.