Quaternary glaciations in southern Fennoscandia: evidence from southwestern Norway and the northern North Sea region

Abstract

Based on records from the northern North Sea and southern Norway, Quaternary Fennoscandian glaciations are described and discussed. Maximum glaciation, defined as the presence of shelf edge glaciation, an ice stream flowing out of the Norwegian Channel and most likely an ice divide over the central part of Fennoscandia (Sweden, Gulf of Bothnia), occurred for the first time in the late Cenozoic at ca. 1.1 myr (the Fedje Glaciation). This glaciation was followed by a ca. 600 kyr period with at least two glaciations with ice extension somewhat larger than the Younger Dryas event in the region. The first maximum glaciation of the Bruhnes Chron was during isotope stage 12 and was followed by repeated maximum glaciations within each of the light isotopic stages until stage 2. During the Weichselian, the southwestern part of the Fennoscandian ice sheet reached maximum position three times (sometime between 22 and 28, 37 and 50, and 60 and 80 ka). Limited glaciations probably occurred during stadials between the early and middle Weichselian interstadials, between 500 ka and 1.1 Myr, and most likely also prior to 1.1 Myr. Deep Norwegian Sea Ice Rafted Detritus (IRD) records, reflecting contributions from several different ice sheets (Fennoscandian, Barents Sea, Iceland and Greenland), each with large variations in history of ice extent to their respective margins, yet to some degree they reflect the glaciation of the northern North Sea region with an increasing IRD input around 1.1 Myr and a relatively low input of North Sea components, during some cycles around the B/M boundary. Maximum glaciations occurred during insolation minima in the earlier part of the Middle Pleistocene, however, not all such minima are reflected by maximum glaciation in southern parts of Fennoscandia. The relatively poor chronological control and non-continuous character of the data on Weichselian interstadials/stadials precludes a clear relationship to atmospheric changes recorded in Greenland ice cores, as well as to precession and/or obliquity cycles in insolation.