DOI: 10.1016/j.quascirev.2014.01.015
Scopus记录号: 2-s2.0-84894297811
论文题名: Glacially-megalineated limestone terrain of Anticosti Island, Gulf of St. Lawrence, Canada; onset zone of the Laurentian Channel Ice Stream
作者: Eyles N. ; Putkinen N.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2014
卷: 88 起始页码: 125
结束页码: 134
语种: 英语
英文关键词: Eastern Canada
; Laurentian Channel Ice Stream
; Laurentide Ice Sheet
; Onset zone
英文摘要: Anticosti is a large elongate island (240km long, 60km wide) in eastern Canada within the northern part of a deep water trough (Gulf of St. Lawrence) that terminates at the Atlantic continental shelf edge. The island's Pleistocene glaciological significance is that its long axis lay transverse to ice from the Quebec and Labrador sectors of the Laurentide Ice Sheet moving south from the relatively high-standing Canadian Shield. Recent glaciological reconstructions place a fast-flowing ice stream along the axis of the Gulf of St. Lawrence but supporting geologic evidence in terms of recognizing its hard-bedded onset zone and downstream streamlined soft bed is limited. Anticosti Island consists of gently southward-dipping limestone plains composed of Ordovician and Silurian limestones (Vaureal, Becscie and Jupiter formations) with north-facing escarpments transverse to regional ice flow. Glacial deposits are largely absent and limestone plains in the higher central plateau of the island retain a relict apparently 'preglacial' drainage system consisting of deeply-incised dendritic bedrock valleys. In contrast, the bedrock geomorphology of the lower lying western and eastern limestone plains of the island is strikingly different having been extensively modified by glacial erosion. Escarpments are glacially megalineated with a distinct 'zig-zag' planform reflecting northward-projecting bullet-shaped 'noses' (identified as rock drumlins) up to 2km wide at their base and 4km in length with rare megagrooved upper surfaces. Drumlins are separated by southward-closing, funnel-shaped 'through valleys' where former dendritic valleys have been extensively altered by the streaming of basal ice through gaps in the escarpments. Glacially-megalineated bedrock terrain such as on the western and eastern flanks of Anticosti Island is elsewhere associated with the hard-bedded onset zones of fast flowing ice streams and provides important ground truth for the postulated Laurentian Channel Ice Stream (LCIS) within the Gulf of St. Lawrence sector of the Laurentide Ice Sheet. © 2014 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60355
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Physical and Environmental Sciences, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, ON M1C 1A4, Canada; Geological Survey of Finland, P.O. Box 97, F1-67101 Kokkola, Finland
Recommended Citation:
Eyles N.,Putkinen N.. Glacially-megalineated limestone terrain of Anticosti Island, Gulf of St. Lawrence, Canada; onset zone of the Laurentian Channel Ice Stream[J]. Quaternary Science Reviews,2014-01-01,88