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 i n 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 souther n Iceland show a fairly distinct trend during the Pliocene-Pleistocene transition indicating the progressive growth of an ice sheet from sou theast toward the north and west. The correlations are based on K/Ar d ates and paleomagnetic studies. A total of 11 glacial horizons are rec orded 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. Wel l over 20 glacial horizons have been identified in the stratigraphic c olumn in Iceland. Full-scale glacial-interglacial cyclicity with regio nal ice cover is indicated at approximately 2.6 myr. A further amplifi cation 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. (C) 1994 University of Washington.