QUATERNARY SEQUENCES AND THEIR RELATIONS TO THE PRE-QUATERNARY IN THEVICINITY OF ANHOLT, KATTEGAT, SCANDINAVIA

The stratigraphic record from a boring penetrating the 104 m thick Qua ternary sequence on the island of Anholt is summarized. The spatial di stribution of the pre-Quaternary formations and the surface topography of these are described on the basis of reflection seismic profiles. I t is concluded that Anholt is located in the crestal zone of a southea st-northwest trending anticline in the pre-Quaternary. The anticline w as formed during the Late Cretaceous-Early Tertiary inversion episodes and was later deeply truncated by erosion. A southeast-northwest tren ding erosional channel, c. 2 km wide and with a maximum depth c. 250 m below sea level, is located southeast of Anholt along the crest of th e anticline. This channel is not present at the bore locality. Althoug h no direct correlation from the boring to the seismic profiles could be achieved it is argued that a strong reflection near the base of the Quaternary outside the channel may be correlated with the Saalian-Eem ian complex found in the boring. Three younger sequences of probable E arly and Middle Weichselian, Late Glacial and Holocene age respectivel y have been recognized. The Late Glacial and Holocene sediments appear to have been deposited in erosional troughs and channels cut into a s equence of Lower and Middle Weichselian sediments. Post-Eemian till de posits or other evidence unambiguously indicating the presence of Weic hselian glaciers have not been found, either in the boring or in the s eismic profiles. It is therefore assumed that the erosion of the Lower -Middle Weichselian sequence was of fluvial origin and can be ascribed to the lowstand period of the Weichselian glacial period. The western part of Anholt can possibly be regarded as an erosional remnant of th e Lower-Middle Weichselian sequence.