DOI: 10.1016/j.quascirev.2016.09.002
Scopus记录号: 2-s2.0-84987973853
论文题名: Subglacial conditions and Scandinavian Ice Sheet dynamics at the coarse-grained substratum of the fore-mountain area of southern Poland
作者: Salamon T.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2016
卷: 151 起始页码: 72
结束页码: 87
语种: 英语
英文关键词: Coarse-grained substratum
; Fore-mountain area
; Ice sheet dynamics
; Pleistocene
; Subglacial till
Scopus关键词: Dynamics
; Glacial geology
; Glaciers
; Groundwater
; High pressure effects
; Interfaces (materials)
; Landforms
; Sea ice
; Sediments
; Coarse-grained
; Fore-mountain area
; Ice sheet dynamics
; Pleistocene
; Subglacial till
; Ice
; alluvial fan
; deformation
; film
; groundwater flow
; ice flow
; ice margin
; meltwater
; permafrost
; Pleistocene
; Scandinavian Ice Sheet
; sedimentology
; structural analysis
; subglacial deposit
; substrate
; temporal variation
; till
; Carpathians
; Poland [Central Europe]
英文摘要: The fore-mountain areas of southern Poland are locally composed of the coarse-grained sediments of alluvial fans, which created unusual conditions under the advancing Scandinavian Ice Sheet during the Elsterian glaciation. This highly permeable substratum potentially enabled rapid outflow of meltwater from the ice sheet base, thereby reducing the water pressure and strongly influencing the ice sheet dynamics. The subglacial conditions and the relationship between the ice sheet behaviour and its coarse-grained substratum were studied at the foreland of the western Carpathian Mountains. The sedimentological and structural analysis of the till and related sediments that were deposited above the alluvial gravel of the fore-mountain fans are presented. The study indicates that despite the high permeability of the coarse-grained substratum, it did not slow the ice sheet movement. Conversely, the ice sheet moved mainly due to basal slip and locally shallow deformations. This was a consequence of very high basal water pressure, which resulted largely from the presence of permafrost that restricted subglacial groundwater outflow. In addition, the ice sheet substratum was inclined opposite to the direction of its movement, increasing the pressure of the subglacial water. Numerous subhorizontal sandy laminae within the till indicate that the meltwater from the ice sheet base was drained by a water film along the ice/bed interface. The water escape structures within the till and subtill sediments indicate the occasional instability of the ice sheet hydrological system and suggest that the meltwater was periodically stored in the ice sheet base. Temporal changes occurring in the ice sheet hydrological system might indicate variations in the ice sheet behaviour; i.e. phases of relatively fast ice flow and phases of ice stagnation. The latter were probably correlated with the freezing of the ice margin to its base. The study shows how the coarse-grained substratum could potentially influence ice sheet behaviour and provides a broader look on the factors controlling the dynamics of the Pleistocene ice sheets, which soft-sediment substrata in many areas were texturally varied. © 2016 Elsevier Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59423
Appears in Collections: 过去全球变化的重建
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作者单位: Faculty of Earth Science, University of Silesia, Będzińska 60, Sosnowiec, Poland
Recommended Citation:
Salamon T.. Subglacial conditions and Scandinavian Ice Sheet dynamics at the coarse-grained substratum of the fore-mountain area of southern Poland[J]. Quaternary Science Reviews,2016-01-01,151