气候变化领域集成服务门户(CCPortal): Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics

CCPortal

DOI	10.5194/tc-15-1517-2021
	Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics
	Hofstede C.; Beyer S.; Corr H.; Eisen O.; Hattermann T.; Helm V.; Neckel N.; Smith E.C.; Steinhage D.; Zeising O.; Humbert A.
发表日期	2021
ISSN	19940416
起始页码	1517
结束页码	1535
卷号	15 期号:3
英文摘要	Curvilinear channels on the surface of an ice shelf indicate the presence of large channels at the base. Modelling studies have shown that where these surface expressions intersect the grounding line, they coincide with the likely outflow of subglacial water. An understanding of the initiation and the ice ocean evolution of the basal channels is required to understand the present behaviour and future dynamics of ice sheets and ice shelves. Here, we present focused active seismic and radar surveys of a basal channel, 950m wide and 200m high, and its upstream continuation beneath Support Force Glacier, which feeds into the Filchner Ice Shelf, West Antarctica. Immediately seaward from the grounding line, below the basal channel, the seismic profiles show an 6:75 km long, 3.2 km wide and 200m thick sedimentary sequence with chaotic to weakly stratified reflections we interpret as a grounding line fan deposited by a subglacial drainage channel directly upstream of the basal channel. Further downstream the seabed has a different character; it consists of harder, stratified consolidated sediments, deposited under different glaciological circumstances, or possibly bedrock. In contrast to the standard perception of a rapid change in ice shelf thickness just downstream of the grounding line, we find a flat topography of the ice shelf base with an almost constant ice thickness gradient along-flow, indicating only little basal melting, but an initial widening of the basal channel, which we ascribe to melting along its flanks. Our findings provide a detailed view of a more complex interaction between the ocean and subglacial hydrology to form basal channels in ice shelves. © 2021 BMJ Publishing Group. All rights reserved.
英文关键词	grounding line; ice shelf; ice thickness; outflow; sedimentary sequence; stratification; subglacial environment; Antarctica; West Antarctica
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202331
作者单位	Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, 27570, Germany; British Antarctic Survey, National Environmental Research Council, Cambridge, CB3 0ET, United Kingdom; Department of Geosciences, University of Bremen, Klagenfurter Straße 2-4, Bremen, 28359, Germany; Norwegian Polar Institute, Framsenteret, Hjalmar Johansens gate 14, Tromsø, 9296, Norway; School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom
推荐引用方式 GB/T 7714	Hofstede C.,Beyer S.,Corr H.,et al. Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics[J],2021,15(3).
APA	Hofstede C..,Beyer S..,Corr H..,Eisen O..,Hattermann T..,...&Humbert A..(2021).Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics.Cryosphere,15(3).
MLA	Hofstede C.,et al."Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics".Cryosphere 15.3(2021).