scholarly journals The Middle Wisconsinan History of the Laurentide Ice Sheet

2008 ◽  
Vol 41 (2) ◽  
pp. 215-235 ◽  
Author(s):  
Lynda A. Dredge ◽  
L. Harvey Thorleifson
Keyword(s):  
Great Lakes ◽  
Dynamic Instability ◽  
Ice Sheet ◽  
Ice Cover ◽  
The Arctic ◽  
Hudson Bay ◽  
Sea Level Changes ◽  
Hudson Bay Lowlands ◽  
Climate Indicators ◽  
Western Arctic

ABSTRACT Evidence for Middle Wisconsinan ice limits and climates comes from sites scattered around the periphery of the Laurentide Ice domain and from the Hudson Bay Lowlands. Interpretations are based on dated wood, peat, shell and sediment; biological climate indicators (chiefly cool-climate indicators); and stratigraphie sequences of both glacial and nonglacial units. The best evidence comes from the prairie provinces and the Great Lakes areas, both of which indicate substantial ice retreat from earlier southern glacial limits, and cool, boreal-tundra climates. The western arctic may have experienced an early warm period but both the western arctic — northwestern plains and eastern maritime areas may later have become ice accumulation areas. Three maps portray various possible ice limits. The first shows substantial ice cover in the arctic, but reduced ice cover in the prairies and Great Lakes, and expanded maritime ice caps (rather than Laurentide Ice) in the southeast and on Baffin Island. This ice mass distribution may reflect Middle Wisconsinan shifts in air masses and ocean currents. Ice volumes generated by this model are in accord with the marine oxygen isotope record and perceived global sea level changes. A modification to this model, which resolves some of the controversy in the Hudson Bay Lowlands, shows a calving bay penetrating into the heart of the ice sheet, induced by dynamic instability of the marine-based ice mass in Hudson Bay during relatively high glacial isostatic and eustatic seas. A third reconstruction portrays extensive climatically induced déglaciation and retains Laurentide ice only in parts of the northwest and Labrador-Ungava, with local ice in the Appalachian-Atlantic region. This model is based on alternative genetic interpretations of lithologic units and reassessment of age assignments.

scholarly journals The Canadian Water Resource Vulnerability Index to Permafrost Thaw (CWRVIPT)

2020 ◽  
Vol 6 (4) ◽  
pp. 437-462
Author(s):  
C. Spence ◽  
M. Norris ◽  
G. Bickerton ◽  
B.R. Bonsal ◽  
R. Brua ◽  
...  
Keyword(s):  
Water Resources ◽  
Water Resource ◽  
Vulnerability Index ◽  
Climatic Conditions ◽  
The Arctic ◽  
Small Scale ◽  
Hudson Bay ◽  
Hudson Bay Lowlands ◽  
Permafrost Thaw ◽  
Canadian North

This study developed and applied a framework for assessing the vulnerability of pan-Canadian water resources to permafrost thaw. The national-scale work addresses a key, but neglected, information gap, as previous research has focused on small scale physical processes and circumpolar trends. The framework was applied to develop the Canadian Water Resources Vulnerability Index to Permafrost Thaw (CWRVIPT) and map the index across the Canadian North. The CWRVIPT is a linearly additive index of permafrost, terrain, disturbance, and climatic conditions and stressors that influence water budgets and aquatic chemistry. Initial results imply water resources in the western Northwest Territories and Hudson Bay Lowlands are most vulnerable to permafrost thaw; however, water resources on Banks, Victoria and Baffin Islands are also relatively vulnerable. Although terrain and permafrost sub-indices are the largest component of the CWRVIPT across a wide swath from the Mackenzie River Delta to the Hudson Bay Lowlands, the climate sub-index is most important farther north over parts of the southern portion of the Arctic Archipelago. The index can be used to identify areas of water resource vulnerability on which to focus observation and research in the Canadian North.

scholarly journals Sedimentary record from the Canada Basin, Arctic Ocean: implications for late to middle Pleistocene glacial history

2017 ◽  
Vol 13 (5) ◽  
pp. 511-531 ◽  
Author(s):  
Linsen Dong ◽  
Yanguang Liu ◽  
Xuefa Shi ◽  
Leonid Polyak ◽  
Yuanhui Huang ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Ice Sheet ◽  
Mineralogical Composition ◽  
Detailed Examination ◽  
Canada Basin ◽  
The Arctic ◽  
Middle Pleistocene ◽  
Sediment Delivery ◽  
Sea Levels ◽  
Western Arctic

Abstract. Sediment core ARC4-BN05 collected from the Canada Basin, Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stage – MIS – 1–15, ca. 0.5–0.6 Ma) as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktic foraminiferal numbers in core ARC4–BN05 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from mineralogical composition. Notably, peaks of dolomite debris, including large dropstones, track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) are inferred from peaks of smectite, kaolinite, and chlorite associated with coarse sediment. Major ESIS sedimentary events occurred in the intervals estimated as MIS 4, MIS 6 and MIS 12. Differences in LIS vs. ESIS inputs can be explained by ice-sheet configurations at different sea levels, sediment delivery mechanisms (iceberg rafting, suspension plumes, and debris flows), and surface circulation. A long-term change in the pattern of sediment inputs, with an apparent step change near the estimated MIS 7–8 boundary (ca. 0.25 Ma), presumably indicates an overall glacial expansion at the western Arctic margins, especially in North America.

scholarly journals Laurentide Ice-Flow Patterns: A Historical Review, and Implications of the Dispersal of Belcher Islands Erratics

2007 ◽  
Vol 44 (2) ◽  
pp. 113-136 ◽  
Author(s):  
Victor K. Prest
Keyword(s):  
Ice Sheet ◽  
Historical Review ◽  
Flow Patterns ◽  
The Arctic ◽  
Laurentide Ice Sheet ◽  
Complex Nature ◽  
Hudson Bay ◽  
Ice Flow ◽  
Flow Models ◽  
The North

ABSTRACTThis paper deals with the evolution of ideas concerning the configuration of flow patterns of the great inland ice sheets east of the Cordillera. The interpretations of overall extent of Laurentide ice have changed little in a century (except in the Arctic) but the manner of growth, centres of outflow, and ice-flow patterns, remain somewhat controversial. Present geological data however, clearly favour the notion of multiple centres of ice flow. The first map of the extent of the North American ice cover was published in 1881. A multi-domed concept of the ice sheet was illustrated in an 1894 sketch-map of radial flow from dispersal areas east and west of Hudson Bay. The first large format glacial map of North America was published in 1913. The binary concept of the ice sheet was in vogue until 1943 when a single centre in Hudson Bay was proposed, based on the westward growth of ice from Labrador/Québec. This Hudson dome concept persisted but was not illustrated until 1977. By this time it was evident from dispersal studies that the single dome concept was not viable. Dispersal studies clearly indicate long-continued westward ice flow from Québec into and across southern Hudson Bay, as well as eastward flow from Keewatin into the northern part of the bay. Computer-type modelling of the Laurentide ice sheet(s) further indicates their complex nature. The distribution of two indicator erratics from the Proterozoicage Belcher Island Fold Belt Group help constrain ice flow models. These erratics have been dispersed widely to the west, southwest and south by the Labrador Sector of more than one Laurentide ice sheet. They are abundant across the Paleozoic terrain of the Hudson-James Bay lowland, but decrease in abundance across the adjoining Archean upland. Similar erratics are common in northern Manitoba in the zone of confluence between Labrador and Keewatin Sector ice. Scattered occurences across the Prairies occur within the realm of south-flowing Keewatin ice. As these erratics are not known, and presumably not present, in Keewatin, they indicate redirection and deposition by Keewatin ice following one or more older advances of Labrador ice. The distribution of indicator erratics thus test our concepts of ice sheet growth.

scholarly journals Sedimentary record from the Canada Basin, Arctic Ocean: implications for late to middle Pleistocene glacial history

2017 ◽  
Author(s):  
Linsen Dong ◽  
Yanguang Liu ◽  
Xuefa Shi ◽  
Leonid Polyak ◽  
Yuanhui Huang ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Ice Sheet ◽  
Mineralogical Composition ◽  
Detailed Examination ◽  
Canada Basin ◽  
The Arctic ◽  
Middle Pleistocene ◽  
14C Dating ◽  
Sediment Delivery ◽  
Western Arctic

Abstract. Sediment core ARC4–BN05 collected from the Canada Basin, Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stages (MIS) 1–15, ca. 0.5–0.6 Ma) as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS 14C dating of the youngest sediments. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktonic foraminiferal numbers in core ARC4–BN05 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from mineralogical composition. Notably, peaks of dolomite debris, including large dropstones, track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) are inferred from peaks of smectite, kaolinite, and chlorite associated with coarse sediment. Major ESIS sedimentary events occurred in the intervals estimated as MIS 4, MIS 6 and MIS 12. Differences in LIS vs. ESIS inputs can be explained by ice-sheet configurations at different sea levels, sediment delivery mechanisms (iceberg rafting, suspension plumes, and debris flows), and surface circulation. A long-term change in the pattern of sediment inputs, with an apparent step change near the estimated MIS 7/8 boundary (ca. 0.25 Ma), presumably indicates an overall glacial expansion at the western Arctic margins, especially in North America.

Correlation of sea-level curves for the Lower Silurian of the Bruce Peninsula and Lake Timiskaming District (Ontario)

1982 ◽  
Vol 19 (5) ◽  
pp. 962-974 ◽  
Author(s):  
Valerie R. Colville ◽  
Markes E. Johnson
Keyword(s):  
Great Lakes ◽  
Sea Level ◽  
Hudson Bay ◽  
Strong Correlations ◽  
The South ◽  
Upper Peninsula ◽  
Level Curves ◽  
Lower Silurian ◽  
Hudson Bay Lowlands ◽  
Open Connection

Paleobathymetric interpretation of strata from the Bruce Peninsula and Lake Timiskaming District of Ontario shows strong correlations with data from the Michigan Upper Peninsula and Ontario's Manitoulin Island. Three to four cycles of fluctuating sea level occurred during Early Silurian (Llandoverian) time throughout much of the northern Great Lakes area, and involved the highly regular replacement of ostracode–vermiform, coral–algal, and pentamerid communities by one another. Although exposure is more limited than on Manitoulin Island or the Michigan Upper Peninsula, important clues regarding Early Silurian geography are found in strata of the Bruce Peninsula and Lake Timiskaming District. Continued thinning of stratigraphic units and an increased incidence of disconformities from north to south on the Bruce Peninsula suggest the episodic rise of the Algonquin Arch farther to the south and west. Contrary to earlier paleogeographic reconstructions, the patterns of community changeovers preserved in the Silurian outlier of the Lake Timiskaming District indicate a persistent, open connection between the seas of the northern Great Lakes area and the Hudson Bay Lowlands. This interpretation is more in keeping with recent paleontologic work on faunal distributions.

scholarly journals Global warming triggers the loss of a key Arctic refugium

2013 ◽  
Vol 280 (1772) ◽  
pp. 20131887 ◽  
Author(s):  
K. M. Rühland ◽  
A. M. Paterson ◽  
W. Keller ◽  
N. Michelutti ◽  
J. P. Smol
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Sediment Cores ◽  
Freshwater Ecosystems ◽  
The Arctic ◽  
Hudson Bay ◽  
Native Communities ◽  
Hudson Bay Lowlands ◽  
Short Period

We document the rapid transformation of one of the Earth's last remaining Arctic refugia, a change that is being driven by global warming. In stark contrast to the amplified warming observed throughout much of the Arctic, the Hudson Bay Lowlands (HBL) of subarctic Canada has maintained cool temperatures, largely due to the counteracting effects of persistent sea ice. However, since the mid-1990s, climate of the HBL has passed a tipping point, the pace and magnitude of which is exceptional even by Arctic standards, exceeding the range of regional long-term variability. Using high-resolution, palaeolimnological records of algal remains in dated lake sediment cores, we report that, within this short period of intense warming, striking biological changes have occurred in the region's freshwater ecosystems. The delayed and intense warming in this remote region provides a natural observatory for testing ecosystem resilience under a rapidly changing climate, in the absence of direct anthropogenic influences. The environmental repercussions of this climate change are of global significance, influencing the huge store of carbon in the region's extensive peatlands, the world's southern-most polar bear population that depends upon Hudson Bay sea ice and permafrost for survival, and native communities who rely on this landscape for sustenance.

scholarly journals Investigating the Local Scale Influence of Sea Ice on Greenland Surface Melt

2017 ◽  
Author(s):  
Julienne C. Stroeve ◽  
John R. Mioduszewski ◽  
Asa Rennermalm ◽  
Linette N. Boisvert ◽  
Marco Tedesco ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Rapid Decline ◽  
Baffin Bay ◽  
Sheet Surface ◽  
Surface Melt

Abstract. Rapid decline in Arctic sea ice cover in the 21st century may have wide-reaching effects on the Arctic climate system, including the Greenland ice sheet mass balance. Here, we investigate whether local changes in sea ice around the Greenland ice sheet have had an impact on Greenland surface melt. Specifically, we investigate the relationship between sea ice concentration, the timing of melt onset and open water fraction surrounding Greenland with ice sheet surface melt using a combination of remote sensing observations, and outputs from a reanalysis model and a regional climate model for the period 1979–2015. Statistical analysis points to covariability between Greenland ice sheet surface melt and sea ice within Baffin Bay and Davis Strait. While some of this covariance can be explained by simultaneous influence of atmospheric circulation anomalies on both the sea ice cover and Greenland melt, within Baffin Bay we find a modest correlation between detrended melt onset over sea ice and the adjacent ice sheet melt onset. This correlation appears to be related to increased transfer of sensible and latent heat fluxes from the ocean to the atmosphere in early sea ice melt years, increasing temperatures and humidity over the ice sheet that in turn initiate ice sheet melt.

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