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Late Pleistocene and Holocene deposits in the witch and fladen ground area, Northern North Sea

1979; Elsevier BV; Volume: 13; Issue: 1 Linguagem: Inglês

10.1016/0077-7579(79)90031-0

1873-1406

J H Fred Jansen, J.W.C. Doppert, K. Hoogendoorn-Toering, John Jong, G. Spaink,

Geological formations and processes

Determinations of carbonate, total N, and organic C content, grain size distributions, analyses of Foraminifera, molluscs and pollen, as well as two 14C data of cores taken in the Witch and Fladen Ground area, were used to supplement earlier interpretations of acoustical reflection records, in an attempt to clarify the Late Pleistocene and Holocene history of the northern North Sea. Starting from below, the Lower and Upper Swatchway Beds, containing not only glaciomarine deposits but also temperate marine sediments, are shown to be of at least Middle Weichselian and possibly of Eemian age. The overlying Hills Deposits consist of a subglacial till, forming the base of a morainic facies, with arctic glaciomarine sediments above and alongside it. The postglacial rise of the sea level and the increase of sea water temperature were recorded in the glaciomarine Fladen Deposits and marine Lower Witch Deposits. For the greater part sedimentation ended during Boreal times (pollen zone IIa2) with the formation of the Upper Witch Deposits, a veneer of fine sands which is correlated with the development of the East Bank Deposit northeast of Dogger Bank. The succession is correlated with a sequence of deposits in a system of buried channels between Witch Ground and Dogger Bank. A belt of tunnel valleys marks the maximum Weichselian ice extension, which occurred at roughly the time of formation of the Hills Deposits. A Witch Ground shore line, probably of about 15 000 y BP, is present at approximately 110 m below sea level, and is proposed to represent the lowest level of the last Weichselian substage.