Growth of an Intermittent Ice Sheet in Iceland during the Late Pliocene and Early Pleistocene

Deep-sea paleoclimatic records show that the Quaternary climate around Iceland was, and probably still is, very sensitive to rapid shifts in North Atlantic oceanic circulation. Studies of several key sections in Iceland indicate that similar oscillations are reflected in the late Pliocene and early Pleistocene terrestrial stratigraphy. Correlations between six rock sequences in western, northern, eastern, and southern Iceland show a fairly distinct trend during the Pliocene-Pleistocene transition indicating the progressive growth of an ice sheet from southeast toward the north and west. The correlations are based on K/Ar dates and paleomagnetic studies. A total of 11 glacial horizons are recorded in a stratigraphic column from eastern Iceland extending back 6.5 myr. In western Iceland, 7 glacial horizons are preserved in a rock section dated from 7.0 to 1.8 myr, and in northern Iceland 14 glacial horizons are identified in a section that extends back to 9.0 myr. Well over 20 glacial horizons have been identified in the stratigraphic column in Iceland. Full-scale glacial-interglacial cyclicity with regional ice cover is indicated at approximately 2.6 myr. A further amplification leading to islandwide glaciations is identified at 2.2-2.1 myr. These results show that changes in the ice cover in Iceland correlate with the deep-sea oxygen isotope records from benthic and planktonic foraminifera as well as IRD studies from the North Atlantic.