PLIOPLEISTOCENE FORAMINIFERAL STRATIGRAPHY AND CORRELATION IN THE CENTRAL NORTH-SEA

A detailed foraminiferal stratigraphy is presented for the Plio-Pleistocene sequence of the Central North Sea region. These results are based on investigations carried out on seven boreholes, and a detailed foraminiferal stratigraphy is presented here for the Josephine borehole 30/13-2x. The Pliocene-Pleistocene boundary is placed at the last common occurrence of Cibicides grossa in the Josephine hole at a depth of 700 m. Cassidulina teretis is the dominant species in the Pliocene, and it continues with decreasing frequencies into the Early Pleistocene. The boundary between Early and Middle Pleistocene occurs at a depth of about 210 m in the borehole. Correlation from west to east in the Central North Sea reveals an extremely thick Pliocene (> 400 m) and Early Pleistocene (500 m) sequence at the Josephine site. This sequence thins out both to the west and to the east. This, together with the palaeoenvironmental evidence present at the Josephine site, indicates that continuous tectonic subsidence occurred during the Pliocene and Early Pleistocene in the Central Graben. Variations in the thickness of the Middle and Late Pleistocene units in the region is probably due to pronounced glacial chanelling.