HR: 1340h
AN: PP33B-0924    [Abstracts]
TI: Severnaya Zemlya, Arctic Russia: a Middle to Late Quaternary Kara Sea Ice Sheet(s) Nucleation Area
AU: * M\H{o}ller, P
EM: per.moller@geol.lu.se
AF: Department of Geology, Centre for GeoBiosphere Science, Lund university, S\H{o}lvegatan 12, Lund, SE-223 62 Sweden
AU: Ing\'{o}lfsson, \
EM: oi@hi.is
AF: Department of Geology and Geography, University of Island, Dunhagi 3, Reykjavik, IS-101 Iceland
AU: Lubinski, D
EM: david.lubinski@spot.colorado.edu
AF: Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Campus Box 450, Boulder, CO 80309-0450 United States
AU: Forman, S L
EM: slf@uic.edu
AF: Department of Earth & Environmental Sciences, Luminescence Dating Research Laboratory, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, IL 60607-7059 United States
AB: With a position on the north-eastern flank of any Kara Sea-based ice sheet, stratigraphic data from the Severnaya Zemlya islands (ZS) is crucial for any ice-sheet reconstruction. This areas was, however, excluded during the recently terminated QUEEN project, covering the glacial history of the last glacial cycle from the Kola Peninsula in the west to the Taymyr Peninsula in the east. In order to resolve this we launched a research programme with two field seasons (2002 and 2003) on SZ, with key locations on October Revolution Island. Our main effort was put into the stratigraphy along the Ozernaya River. Here we mapped four marine sequences, divided by glacial tills. The lowermost marine sequence is shallow-marine deltaic sand (M-1), containing numerous in situ fossil mollusc shells, as well as driftwood and whalebones. It is underlain by the lowermost till unit (T-1) and tectonized by a glacier which advanced southwards from inland SZ towards the Kara Sea, depositing the second till (T-2). Clayey, deeper-water marine sediments (M-2) in turn overlie this till, containing numerous in situ fossil mollusc shells. Clast fabrics from the above-lying till (T-3) show that also this glacier advance was southwards into the Kara Sea. The next marine unit (M-3) shows a transition from marine clay to sandy sublittoral deposit and beach gravels, containing numerous in situ fossil mollusc shells. The beach gravels, in turn, are covered by a thin glacial till (T-4), showing incorporation of the underlying beach gravels and a clast fabric indicating glacier advance southwards into the Kara Sea. Our youngest marine sequence (M-4), not present in our key locality, reveal a transition from marine clay into well-developed beach ridges, which could be mapped over long distances on altitudes not higher than c. 40 m a.s.l. The data indicate at least four Late Quaternary major glaciations on October Revolution Island, spanning - according to our extensive but not yet completed dating programme - Marine Isotope Stages (MIS) 10 to MIS 4. During stadial conditions local ice caps grew and expanded and probably coalesced with ice from Taymyr and Novaya Zemlya to form Kara Sea-based ice sheets. The significant isostatic depression, causing subsequent deposition of marine sediments and formation of raised beaches at altitudes up to 100-130 m a.s.l. suggests that these glaciations were on regional scales, not only expansions of local glaciers, and that SZ was an ice-sheet nucleation area.
DE: 9315 Arctic region
DE: 9604 Cenozoic
DE: 4556 Sea level variations
DE: 3022 Marine sediments--processes and transport
DE: 1827 Glaciology (1863)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting