TY - JOUR
T1 - The last Scandinavian ice sheet in northwestern Russia: ice flow patterns and decay dynamics
AU - Demidov, L.
AU - Houmark-Nielsen, Michael
AU - Kjær, Kurt Henrik
AU - Larsen, E.
PY - 2006
Y1 - 2006
N2 - Advance of the Late Weichselian (Valdaian) Scandinavian Ice Sheet (SIS) in northwestern Russia took place after a period of periglacial conditions. Till of the last SIS, Bobrovo till, overlies glacial deposits from the previous Barents and Kara Sea ice sheets and marine deposits of the Last Interglacial. The till is identified by its contents of Scandinavian erratics and it has directional properties of westerly provenance. Above the deglaciation sediments, and extra marginally, it is replaced by glaciofluvial and glaciolacustrine deposits. At its maximum extent, the last SIS was more restricted in Russia than previously outlined and the time of termination at 18-16 cal. kyr BP was almost 10 kyr delayed compared to the southwestern part of the ice sheet. We argue that the lithology of the ice sheets' substrate, and especially the location of former proglacial lake basins, influenced the dynamics of the ice sheet and guided the direction of flow. We advocate that, while reaching the maximum extent, lobe-shaped glaciers protruded eastward from SIS and moved along the path of water-filled lowland basins. Ice-sheet collapse and deglaciation in the region commenced when ice lobes were detached from the main ice sheet. During the Lateglacial warming, disintegration and melting took place in a 200-600 km wide zone along the northeastern rim of SIS associated with thick Quaternary accumulations. Deglaciation occurred through aerial downwasting within large fields of dead ice developed during successively detached ice lobes. Deglaciation led to the development of hummocky moraine landscapes with scattered periglacial and ice-dammed lakes, while a sub-arctic flora invaded the region.
Udgivelsesdato: August 2006
AB - Advance of the Late Weichselian (Valdaian) Scandinavian Ice Sheet (SIS) in northwestern Russia took place after a period of periglacial conditions. Till of the last SIS, Bobrovo till, overlies glacial deposits from the previous Barents and Kara Sea ice sheets and marine deposits of the Last Interglacial. The till is identified by its contents of Scandinavian erratics and it has directional properties of westerly provenance. Above the deglaciation sediments, and extra marginally, it is replaced by glaciofluvial and glaciolacustrine deposits. At its maximum extent, the last SIS was more restricted in Russia than previously outlined and the time of termination at 18-16 cal. kyr BP was almost 10 kyr delayed compared to the southwestern part of the ice sheet. We argue that the lithology of the ice sheets' substrate, and especially the location of former proglacial lake basins, influenced the dynamics of the ice sheet and guided the direction of flow. We advocate that, while reaching the maximum extent, lobe-shaped glaciers protruded eastward from SIS and moved along the path of water-filled lowland basins. Ice-sheet collapse and deglaciation in the region commenced when ice lobes were detached from the main ice sheet. During the Lateglacial warming, disintegration and melting took place in a 200-600 km wide zone along the northeastern rim of SIS associated with thick Quaternary accumulations. Deglaciation occurred through aerial downwasting within large fields of dead ice developed during successively detached ice lobes. Deglaciation led to the development of hummocky moraine landscapes with scattered periglacial and ice-dammed lakes, while a sub-arctic flora invaded the region.
Udgivelsesdato: August 2006
KW - Faculty of Science
KW - Scandinavian ice sheet
KW - northwest Russia
KW - flow pattern
U2 - 10.1080/03009480600781883
DO - 10.1080/03009480600781883
M3 - Journal article
SN - 0300-9483
VL - 35
SP - 425
EP - 443
JO - Boreas
JF - Boreas
IS - 3
ER -