DOI: 10.1016/j.quascirev.2014.06.027
Scopus记录号: 2-s2.0-84903993824
论文题名: Timing of terminal Pleistocene deglaciation at high elevations in southern and central British Columbia constrained by 10Be exposure dating
作者: Margold M. ; Stroeven A.P. ; Clague J.J. ; Heyman J.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2014
卷: 99 起始页码: 193
结束页码: 202
语种: 英语
英文关键词: Be-10 exposure dating
; Cordilleran ice sheet
; Deglaciation
Scopus关键词: Geochronology
; Glacial geology
; Glaciers
; Isotopes
; Landforms
; Marble
; Sea level
; Shielding
; Snow
; Be-10 exposure dating
; Climate fluctuations
; Cordilleran ice sheet
; Deglaciations
; Last Glacial Maximum
; Marine oxygen isotopes
; Northwest british columbia
; Younger dryas chronozone
; Ice
; beryllium isotope
; climate variation
; data set
; dating method
; deglaciation
; geochronology
; ice cover
; ice sheet
; Last Glacial Maximum
; Pleistocene
; North America
英文摘要: The Cordilleran Ice Sheet (CIS) covered most of British Columbia and southern Yukon Territory at the local Last Glacial Maximum (lLGM) during Marine Oxygen Isotope Stage 2. However, its subsequent demise is not well understood, particularly at high elevations east of its ocean-terminating margin. We present 10Be exposure ages from two high-elevation sites in southern and central British Columbia that help constrain the time of initial deglaciation at these sites. We sampled granodiorite erratics at elevations of 2126-2230m a.s.l. in the Marble Range and 1608-1785m a.s.l. in the Telkwa Range at the western margin of the Interior Plateau. The erratics at both sites are near ice-marginal meltwater channels that delineate the local ice surface slope and thus the configuration of the ice sheet during deglaciation. The locations of the erratics and their relations to meltwater channels ensure that the resulting 10Be ages date CIS deglaciation and not the retreat of local montane glaciers. Our sample sites emerged above the surface of the CIS as its divide migrated westward from the Interior Plateau to the axis of the Coast Mountains. Two of the four samples from the summit area of the Marble Range yielded apparent exposure ages of 14.0±0.7 and 15.2±0.8 ka. These ages are 1.8-3.0 ka younger than the well-established lLGM age of ca17 ka for the Puget lobe of the CIS in Washington State; they are 1.7 ka younger than the lLGM age for the Puget lobe if a snow-shielding correction to their uncertainty-weighted mean age is applied. The other two samples yielded much older apparent exposure ages (20.6±1.4 and 33.0±1.5 ka), indicating the presence of inherited isotopes. Four samples collected from the summit area of the Telkwa Range in the Hazelton Mountains yielded well clustered apparent exposure ages of 10.1±0.6, 10.2±0.7, 10.4±0.5, and 11.5±1.1 ka. Significant present-day snow cover introduces a large uncertainty in the apparent exposure ages from this site. A snow-shielding correction based on present-day snow cover data increases the uncertainty-weighted mean exposure age of the Telkwa Range erratics to 12.4±0.7 ka, consistent with deglacial 14C ages from areas near sea level to the west. Our exposure ages show a thinning of the southern portion of the CIS shortly after the lLGM and persistence of a remnant mountain ice cap in the central Coast Mountains into the Younger Dryas Chronozone. Our data also show that the summit area of the Marble Range was ice-covered during the lLGM. The presence of an ice body of considerable dimension in north-central British Columbia until, or possibly even after, the Younger Dryas highlights the need for geomorphological and geochronological studies of the ice dispersal centre over the Skeena Mountains in northwest British Columbia and the need for better understanding of the response of the CIS to Lateglacial climate fluctuations. © 2014 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60189
Appears in Collections: 过去全球变化的重建
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作者单位: Durham University, Department of Geography, Lower Mountjoy, South Road, Durham DH1 3LE, United Kingdom; Stockholm University, Department of Physical Geography and Quaternary Geology, Bolin Centre for Climate Research, 106 91 Stockholm, Sweden; Simon Fraser University, Department of Earth Sciences, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
Recommended Citation:
Margold M.,Stroeven A.P.,Clague J.J.,et al. Timing of terminal Pleistocene deglaciation at high elevations in southern and central British Columbia constrained by 10Be exposure dating[J]. Quaternary Science Reviews,2014-01-01,99