Foraminifera in the Early Pleistocene Part of the Breiðavík Group, North Iceland

Foraminiferal assemblages have been studied in the Early Pleistocene sediments of the Tjornes section, North Iceland. A systematic description of the foraminiferal contents in three different formations of the Breiðavik Group, i.e., the Horgi Formation, the Þrengingar Formation (Svarthamar Member), and the Mana Formation, is presented. Only the 1.5 Ma old Svarthamar Member (upper part of the Þrengingar Formation) contained enough foraminifera for stratigraphical and environmental interpretations of the Breiðavik Group sediments. The foraminiferal assemblage compositions in the Svarthamar Member indicate a change from arctic to boreal-arctic (subarctic) or even boreal conditions in the sea around Iceland just after the Olduvai event of the Matuyama time interval. This climatic cycle is comparable to the Late Pleistocene glacial-interglacial cycles in the North Atlantic and indicates a northward shift of the Polar Front to a position off North Iceland during at least a part of the Early Pleistocene.