Lithostratigraphy of the Late Saalian to Middle Weichselian Skærumhede Group in Vendsyssel, northern Denmark

Abstract

The Quaternary sedimentary succession in Vendsyssel, northern Denmark, contains a unique, high-resolution record of the last interglacial and glacial periods. There is still much debate, however, about the timing and ice extent in this southwestern part of the Scandinavian Ice Sheet, particularly during the Middle Weichselian. In this study, a detailed lithostratigraphical subdivision is established for the Late Saalian to Middle Weichselian Skaerumhede Group on the basis of numerous, up to 250 m deep, boreholes in Vendsyssel. The sediments mainly consist of marine clays, glaciolacustrine sediments and tills, and the total thickness of the Skaerumhede Group is up to 140 m. Marine intervals have been used as stratigraphical marker units to separate the formations indicative of ice-sheet activity in Vendsyssel, and the timing of the events has been constrained by a large number of optically stimulated luminescence (OSL) and radiocarbon ages. The Skaerumhede Group is subdivided into seven formations and two members, reflecting shifts between marine and terrestrial sedimentation caused by fluctuations of the Scandinavian Ice Sheet and changes in sea level. The lowermost Skaerumhede Till Formation was deposited directly on top of the bedrock during the Warthe advance c. 160-140 kyr BP. Above, there are fine-grained marine sediments, subdivided into the Lower, Middle and Upper Skaerumhede Clay Formations. The marine formations are separated by the Brønderslev Formation related to the Sundsøre ice advance from the north c. 65-60 kyr BP, and the Å sted Formation, deposited during the Ristinge advance from an east-southeastern direction c. 55-50 kyr BP. The uppermost formation in the group is the Lønstrup Klint Formation, which is an upwards-coarsening sequence of mainly glaciolacustrine sediments deposited prior to the Kattegat advance c. 30-29 kyr BP. The new evidence from Vendsyssel has shown that the Skaerumhede Group covers a large area, and that it can be used as a regional stratigraphical marker horizon. Furthermore, it contributes to a better understanding of the timing and extent of glacial events during the Late Saalian to Middle Weichselian in southwest Scandinavia.

Drumlinised glaciofluvial and glaciolacustrine sediments on the Småland peneplain, South Sweden – new information on the growth and decay history of the Fennoscandian Ice Sheets during MIS 3

“…during the climatically very complex MIS 3 (when compared to the preceding very cold MIS 4) and correlate with the suggested time spans for the Ristinge and Klintholm advances into Denmark from streaming ice in the Baltic basin westwards, terminating in fan-shaped patterns. Larsen et al (2009aLarsen et al ( , 2009b, whereas the stratigraphies from southern Denmark build on the work of Houmark-Nielsen (1994, 2003 and Bennike et al (2007). The stratigraphical positions of key localities in southernmost Sweden (the Alnarp valley and Kriegers Flak) are according to discussion in Anjar et al (2014b).…”

“…1A) is now challenged from two very different standpoints. According to Houmark-Nielsen (2004, 2011 and Larsen et al (2009aLarsen et al ( , 2009b, Denmark and southern Sweden were invaded by ice sheets at four different stages during MIS 4e3, from the north across the Norwegian Channel and Kattegatt during very late MIS 4 (the Sundsøre Advance, c. 65e60 ka) and late MIS 3 (the Kattegatt Advance, c. 29e27 ka), and from the east over southern Sweden and through the Baltic Basin with two prominent ice advances into Denmark during MIS 3 (the Ristinge Advance, c. 56e46 ka and the Klintholm Advance, c. 34e30 ka) (Fig. 1A).…”

Substratum control on tunnel-valley formation in Denmark

“…However, as profile B shows (Fig. 6), the ice-marginal hill is dominated by high-resistivity, sandy sediments of the Ribjerg and the Troldbjerg formations Larsen et al 2009). The clayey marine sediments of the Skaerumhede Group are found at depths of 30-50 m b.s.l.…”

“…More than 150-200 m of predominantly clayey and silty marine and glaciolacustrine sediments can be found throughout this area Larsen et al 2009). These sediments constituted the substratum for the Middle and Late Weichselian ice advances.…”

“…5) shows that the interior of the icemarginal hill is composed of low-resistivity sediments, with high-resistivity sediments found on either side of the hill. The low-resistivity sediments comprise silty marine clays of the Skaerumhede Group, whereas the high-resistivity sediments to the west and east comprise glaciolacustrine sandy sediments of the Morild and Ribjerg formations and predominantly sandy valley in-fill of the Morild and Vendsyssel formations, respectively Larsen et al 2009). The marine clays have been glaciotectonically dislocated from depths of c. 40 m b.s.l.…”