scholarly journals Late Weichselian base temperatures of the Scandinavian ice sheet

2019 ◽  
Author(s):  
Anonymous
2019 ◽  
Author(s):  
Dmitry Y. Demezhko ◽  
Anastasia A. Gornostaeva ◽  
Alexander N. Antipin

Abstract. Geothermal estimates of the ground surface temperatures for the last glacial cycle in Northern Europe has been analyzed. During the Middle and Late Weichselian (55–12 kyr BP) a substantial part of this area was covered by the Scandinavian Ice Sheet. The analysis of geothermal data has allowed reconstructing limits of the ice sheet extension and its basal thermal state in the Late Weichselian. Ground surface temperatures outside the ice sheet were extremely low (from −8 to −18 °C). Within the ice sheet, there were both thawed and frozen zones. The revealed temperature pattern is generally consistent with the modern one for the ground surface temperatures in Greenland that makes it possible to consider these ice sheets as analogues. The anomalous climatically induced surface heat flux and orbital insolation of the Earth varied consistently outside the glaciation and independently within the limits of the ice sheet.


2012 ◽  
Vol 60 ◽  
pp. 61-80
Author(s):  
Tillie M. Madsen

The coastal cliff of Halk Hoved, southern Jutland, Denmark, is a major glaciotectonic complex formed by proglacial deformation of the North-East (NE) advance from the Scandinavian Ice Sheet in Late Weichselian. We describe and interpret the pre-, syn- and post-tectonic sedimentary successions and macro-scale architecture of this complex. Initially, the Lillebælt Till Formation (unit 1) and the overlying glaciofluvial sediments (unit 2) were deposited during the Warthe glaciation in Late Saalian. During the NE advance towards the Main Stationary Line (MSL) in Late Weichselian, these sediments were pushed along a décollement surface whereby a thrust-fault complex was formed. In a cross section the complex extends for more than 900 m and consists of eighteen c. 15–20 m thick thrust sheets stacked by piggyback thrusting. Accumulated displacement amounts to at least 235 m along thrust faults dipping at 30–40° towards N-NE, resulting in at least 24% glaciotectonic shortening of the complex. Deformation was presumably facilitated by elevated pore-water pressure in the Lillebælt Till Formation. As the compressive stress exceeded the shear strength of the weakened till, failure occurred, and a décollement horizon formed along the lithological boundary between the Lillebælt Till Formation and the underlying aquifer. During deformation, piggyback basins formed wherein sediments of hyperconcentrated flow (unit 3) and glaciolacustrine diamicton (unit 4) were deposited. The whole thrust-fault complex and the intervening sediments were truncated subglacially as the NE advance finally overrode the complex. Following the retreat of the NE advance, a succession of glaciofluvial sediments (unit 5) and finally the East Jylland Till Formation (unit 6) were deposited during the advance of the Young Baltic Ice Sheet. The Halk Hoved thrust-fault complex is a prominent example of glaciotectonism at the southern fringe of the Scandinavian Ice Sheet.


Boreas ◽  
2005 ◽  
Vol 34 (2) ◽  
pp. 176-185 ◽  
Author(s):  
Cornelia Winguth ◽  
David Mickelson ◽  
Eiliv Larsen ◽  
Jessica Darter ◽  
Carolyn Moeller ◽  
...  

2014 ◽  
Vol 60 (219) ◽  
pp. 29-40 ◽  
Author(s):  
C.C. Clason ◽  
P.J. Applegate ◽  
P. Holmlund

AbstractWe simulated the Late Weichselian extent and dynamics of the Eurasian ice sheets using the shallow-ice approximation ice-sheet model SICOPOLIS. Our simulated Last Glacial Maximum ice-sheet extents closely resemble geomorphological reconstructions, and areas of modelled fast flow are consistent with the known locations of palaeo-ice streams. Motivated by documented velocity response to increased meltwater inputs on Greenland, we tested the sensitivity of the simulated ice sheet to the surface meltwater effect (SME) through a simple parameterization relating basal sliding to local surface melt rate and ice thickness. Model runs including the SME produce significantly reduced ice volume during deglaciation, with maximum ice surface velocities much greater than in similar runs that neglect the SME. We find that the simple treatment of the SME is not applicable across the whole ice sheet; however, our results highlight the importance of the SME for dynamic response to increased melting. The southwest sector of the Scandinavian ice sheet is most sensitive to the SME, with fast flow in the Baltic ice stream region shutting off by 15 ka BP when the SME is turned on, coincident with a retreat of the ice-margin position into the Gulf of Bothnia.


Boreas ◽  
2008 ◽  
Vol 34 (2) ◽  
pp. 176-185 ◽  
Author(s):  
CORNELIA WINGUTH ◽  
DAVID M. MICKELSON ◽  
EILIV LARSEN ◽  
JESSICA R. DARTER ◽  
CAROLYN A. MOELLER ◽  
...  

1999 ◽  
Vol 28 ◽  
pp. 202-208 ◽  
Author(s):  
Anders Clarhäll ◽  
Johan Kleman

AbstractThe Ultevis plateau, northwestern Sweden, has a relief of less than 200 m, yet bears three different kinds of landscape, classified according to the degree of glacial erosion. The first type is restricted mainly to topographic highs and has almost entirely escaped erosion, despite complete and prolonged ice cover during the late Weichselian. The other two landscape types are distinguished depending on whether older land- forms have been completely erased or not. The latter two appear to have undergone erosion only briefly. The transitions between landscape zones are usually sharp, and specific boundary landforms occur. The Scandinavian ice sheet was cold-based in its central areas during its maximum. During the deglaciation, both the dry/wet-base boundary and ice margin migrated inwards, at different speeds. When the ice front retreated faster than the thermal transition zone, the wet-base marginal zone shrank and erosion was reduced or avoided. Where the wet-base zone was of limited longitudinal extent, as on the Ultevis plateau, conversion from a frozen to a thawed bed was incomplete, leaving a patchwork of preserved glacial and non-glacial morphologies.


Boreas ◽  
2007 ◽  
Vol 36 (3) ◽  
pp. 286-306 ◽  
Author(s):  
DAG OTTESEN ◽  
JULIAN A. DOWDESWELL ◽  
JON Y. LANDVIK ◽  
JUERGEN MIENERT

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