Seismic stratigraphy of the Quaternary and its substratum in southeastern Kattegat, Scandinavia

Abstract

Based on c. 1500 km reflection seismic profiles, the Quaternary formations and their pre‐Quaternary substratum in the southeastern Kattegat are described and a geological interpretation is suggested. The major volume of Quaternary deposits is found in a broad north‐northwest south‐southeast trending topographic depression. The substratum consists of Upper Cretaceous limestone in the region north of the Sorgenfrei–Tornquist Zone, and inside this zone older Mesozoic sedimentary rocks and Precambrian crystalline rocks are found. The Quaternary is divided into four seismic units. No direct stratigraphic control is available, but the units are assumed to represent a period ranging from Late Saalian to Holocene. The oldest unit (unit 3) is composed of deposits of supposed Late Saalian to Middle Weichselian age. This unit was severely eroded probably by the Late Weichselian ice sheets in a zone extending 40–50 km from the Swedish coast. Unit 2 represents the Late Weichselian till deposits. North and east of the island of Anholt unit 3 is cut by a system of channels eroded by glacial meltwater. By the erosion a relief up to c. 100 m was formed. After the recession of the Late Weichselian ice, an up to 100 m thick sequence of water‐lain sediments (unit 1) was deposited in the erosional basin and channels. Holocene deposits (unit 0) of considerable thickness have only been identified in the channels in the northern part of the area.

Absolute sea levels and isostatic changes of the eastern North Sea to central Baltic region during the last 900 years

“…In line with a tectonic interpretation of the Sorgenfrei-Tornquist Zone, high-resolution seismic surveys of Kattegat have identified a number of gentle dome structures (Vangkilde-Petersen et al 1993) in the 160-200 m thick early Weichselian to early Holocene marine clays underlying most parts of the northern Kattegat Sea (Knudsen 1986;Lykke-Andersen 1990;Gyldenholm et al 1993;Lykke-Andersen et al 1993a,b;Knudsen et al 1996Knudsen et al , 2009). The domes are comparable to Hornfiskrøn and other islets south of Laesø in terms of size and orientation.…”

“…) in the 160–200 m thick early Weichselian to early Holocene marine clays underlying most parts of the northern Kattegat Sea (Knudsen ; Lykke‐Andersen ; Gyldenholm et al . ; Lykke‐Andersen et al . ,; Knudsen et al .…”

The salt industry on the Danish Kattegat island of Læsø (1150–1652): Hypersaline source, climatic dependence, and environmental impact

“…This assumption is based on reflection seismic studies by Larsen et al ( 1986}, LykkeAndersen et al (1993a, Gyldenholm et al ( 1993) and Vangkilde-Petersen et al ( 1993) of the area between Lres0 and the island Anholt, southeast of Lres0. Such local deformation appears to be particularly important for the fast growth ofHorntiskr0n, Kringelmn, and Langer0n and may have been caused by clay diapirism triggered by dextral strike/slip movements in the well-known large-scale tectonic Sorgenfrei-Tornquist Zone passing through Kattegat, Skane, Bornholm, and Poland (see Mogensen & Korstgard, 2003 ).…”

Seismic stratigraphy of Late Quaternary deposits in the eastern Skagerrak

“…Although there are considerable overlaps with the study by Fa¨lt (1982), the higher resolution in the present investigation allows a more detailed interpretation. Several studies have also been performed in the Kattegat, to the south (Nordberg and Bergsten, 1988;Nordberg, 1989Nordberg, , 1991Gyldenholm et al, 1993;Lykke-Andersen et al, 1993;Klingberg, 1996).…”