Eruption of Mount Meager, British Columbia, during the early Fraser glaciation

2021 ◽  
Author(s):  
James K. Russell ◽  
Martin L. Stewart ◽  
Alexander M. Wilson ◽  
Glyn Williams-Jones
Keyword(s):  
British Columbia ◽  
Volcanic Eruption ◽  
Ice Sheet ◽  
High Elevation ◽  
Pyroclastic Density Current ◽  
Density Current ◽  
Volcanic Complex ◽  
Glacial Cycle ◽  
Volcanic Event ◽  
Field Evidence

A new 40Ar/39Ar date from a pyroclastic density current deposit preserved on the northern slopes of the Lillooet River valley, British Columbia, indicates an explosive volcanic eruption of the Mount Meager Volcanic Complex (MMVC) at 24.3 ± 2.3 ka. The age of this pyroclastic deposit is a record of the second youngest explosive volcanic event for the MMVC and indicates that Mount Meager has erupted, explosively, at least twice in the past ~25,000 years. The age of the volcanic eruption coincides with the early phase of growth of the Late Wisconsin (Fraser) Cordilleran ice sheet. The deposit constrains the distribution and timing of glacier build-up in southwestern British Columbia over the last glacial cycle and suggests that the ice sheet was absent or thin in the upper Lillooet valley at this time. Field evidence suggests the pyroclastic density current was sourced at high elevation near present-day Plinth Peak and was deposited and preserved on the adjoining Lillooet valley wall. Coeval, proximal valley-filling glacial ice was up to ~120 m thick.

scholarly journals Deglaciation of the Cordillera of Western Canada at the end of the Pleistocene

2017 ◽  
Vol 43 (2) ◽  
pp. 449 ◽  
Author(s):  
J.J. Clague
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Ice Cover ◽  
High Elevation ◽  
Coast Mountains ◽  
Western Margin ◽  
Warming Climate ◽  
Glacier Ice ◽  
Cordilleran Ice Sheet ◽  
Exposure Ages

Nearly all of what is now British Columbia and adjacent areas were covered by an ice sheet at the maximum of the Last Glaciation (MIS 2) about 18,000 years ago. By 11,000 years ago, the Cordilleran Ice Sheet had disappeared, a victim of warming climate, eustatic sea-level rise along its western margin, and perhaps a reduction in precipitation. Deglaciation proceeded by frontal retreat at the periphery of the ice sheet and by downwasting, complex frontal retreat, and localized stagnation in its interior areas. The chronology of deglaciation is constrained, albeit with inherent dating errors, by AMS radiocarbon and 10Be surface exposure ages. High-elevation sites at the western margin of the British Columbia Interior Plateau, east of the Coast Mountains, became ice-free between about 15,000 and 12,000 years ago. Ice cover in the southern Coast Mountains was sufficiently extensive during the Younger Dryas Chronozone (12,900-11,700 years ago) that glaciers advanced into low-lying areas north and east of Vancouver. At the same time, however, a labyrinth of dead or dying tongues of glacier ice covered some interior valleys. By 11,000 years ago, ice cover in the Canadian Cordillera was no more extensive than it is today.

Exposure ages from relict lateral moraines overridden by the Fennoscandian ice sheet

2006 ◽  
Vol 65 (1) ◽  
pp. 136-146 ◽  
Author(s):  
Derek Fabel ◽  
David Fink ◽  
Ola Fredin ◽  
Jon Harbor ◽  
Magnus Land ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Last Deglaciation ◽  
Glacial Cycle ◽  
Oxygen Isotope Stage ◽  
Last Glacial ◽  
Cosmogenic Nuclide ◽  
Field Evidence ◽  
Continental Ice Sheets ◽  
Exposure Ages ◽  
The Last Glacial

AbstractLateral moraines constructed along west to east sloping outlet glaciers from mountain centred, pre-last glacial maximum (LGM) ice fields of limited extent remain largely preserved in the northern Swedish landscape despite overriding by continental ice sheets, most recently during the last glacial. From field evidence, including geomorphological relationships and a detailed weathering profile including a buried soil, we have identified seven such lateral moraines that were overridden by the expansion and growth of the Fennoscandian ice sheet. Cosmogenic 10Be and 26Al exposure ages of 19 boulders from the crests of these moraines, combined with the field evidence, are correlated to episodes of moraine stabilisation, Pleistocene surface weathering, and glacial overriding. The last deglaciation event dominates the exposure ages, with 10Be and 26Al data derived from 15 moraine boulders indicating regional deglaciation 9600 ± 200 yr ago. This is the most robust numerical age for the final deglaciation of the Fennoscandian ice sheet. The older apparent exposure ages of the remaining boulders (14,600–26,400 yr) can be explained by cosmogenic nuclide inheritance from previous exposure of the moraine crests during the last glacial cycle. Their potential exposure history, based on local glacial chronologies, indicates that the current moraine morphologies formed at the latest during marine oxygen isotope stage 5. Although numerous deglaciation ages were obtained, this study demonstrates that numerical ages need to be treated with caution and assessed in light of the geomorphological evidence indicating moraines are not necessarily formed by the event that dominates the cosmogenic nuclide data.

Ice-free conditions in southwestern British Columbia at 16000 years BP

1988 ◽  
Vol 25 (6) ◽  
pp. 938-941 ◽  
Author(s):  
John J. Clague ◽  
Ian R. Saunders ◽  
Michael C. Roberts
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Radiocarbon Dates ◽  
Maximum Extent ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

New radiocarbon dates on wood from two exposures in Chilliwack valley, southwestern British Columbia, indicate that this area was ice free and locally forested 16 000 radiocarbon years ago. This suggests that the Late Wisconsinan Cordilleran Ice Sheet reached its maximum extent in this region after 16 000 years BP. The Chilliwack valley dates are the youngest in British Columbia that bear on the growth of the Cordilleran Ice Sheet.

scholarly journals East Antarctic ice sheet stability recorded in a high-elevation ice-cored moraine

2017 ◽  
Vol 159 ◽  
pp. 88-102 ◽  
Author(s):  
Nicole A. Bader ◽  
Kathy J. Licht ◽  
Michael R. Kaplan ◽  
Christine Kassab ◽  
Gisela Winckler
Keyword(s):  
Ice Sheet ◽  
High Elevation ◽  
Antarctic Ice Sheet ◽  
East Antarctic Ice Sheet

scholarly journals Investigating the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle

2009 ◽  
Vol 5 (3) ◽  
pp. 329-345 ◽  
Author(s):  
S. Bonelli ◽  
S. Charbit ◽  
M. Kageyama ◽  
M.-N. Woillez ◽  
G. Ramstein ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Climate Model ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Glacial Cycle ◽  
Last Glacial ◽  
Atmospheric Co2 Concentration ◽  
The Last Glacial

Abstract. A 2.5-dimensional climate model of intermediate complexity, CLIMBER-2, fully coupled with the GREMLINS 3-D thermo-mechanical ice sheet model is used to simulate the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle and to investigate the ice sheets responses to both insolation and atmospheric CO2 concentration. This model reproduces the main phases of advance and retreat of Northern Hemisphere ice sheets during the last glacial cycle, although the amplitude of these variations is less pronounced than those based on sea level reconstructions. At the last glacial maximum, the simulated ice volume is 52.5×1015 m3 and the spatial distribution of both the American and Eurasian ice complexes is in reasonable agreement with observations, with the exception of the marine parts of these former ice sheets. A set of sensitivity studies has also been performed to assess the sensitivity of the Northern Hemisphere ice sheets to both insolation and atmospheric CO2. Our results suggest that the decrease of summer insolation is the main factor responsible for the early build up of the North American ice sheet around 120 kyr BP, in agreement with benthic foraminifera δ18O signals. In contrast, low insolation and low atmospheric CO2 concentration are both necessary to trigger a long-lasting glaciation over Eurasia.

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