Possible Causes of the Variability of Postglacial Uplift in North America

1971 ◽  
Vol 1 (4) ◽  
pp. 522-531 ◽  
Author(s):  
Richard H. Fillon
Keyword(s):  
North America ◽  
Ice Sheet ◽  
Tectonic Activity ◽  
Laurentide Ice Sheet ◽  
Uplift Rate ◽  
Geophysical Research ◽  
Northeastern North America ◽  
Isostatic Uplift ◽  
Uplift Rates ◽  
Consistent Manner

Postglacial uplift data from 33 sites in northeastern North America reveal that during the period from 11,000 years B.P. to 7000 years B.P., glacio-isostatic uplift rates varied in a consistent manner with distance from the former margin of the Laurentide Ice Sheet. The consistent trends of these uplift rate variations with distance from the former ice sheet margin suggest that they were not the result of changes in the rate of ice sheet retreat or local tectonic activity. They instead may have resulted from rebound affected significantly by the earth's viscosity at a depth approximately equal to the wavelength of isostatic deformation [McConnell, R.K., Jr., Journal of Geophysical Research70, 5171 (1965)]. Extremely high viscosities below 600 km, however, probably provide the lower limit for this relationship.

Glaciation of the Torngat Mountains, Northern Labrador

ARCTIC ◽  
1957 ◽  
Vol 10 (2) ◽  
pp. 66 ◽  
Author(s):  
J.D. Ives
Keyword(s):  
North America ◽  
Ice Sheet ◽  
Field Work ◽  
Glacial Period ◽  
Large Area ◽  
International Union ◽  
Northeastern North America ◽  
Glacial Periods

Considers role of these mountains in glaciation of Labrador-Ungava, assessing particularly events in late-Wisconsin times with respect to final disappearance of both continental and local ice masses. Conflicting theories are discussed, and evidence presented, based on physiography and findings from summer 1956 field work, including unmistakable erratics on summits at 4,000-5,000 ft. The highest summits were completely submerged by eastward moving continental ice during the Wisconsin glaciation; local glaciers never reached significant dimensions; rapid melting in situ of thick masses of ice occurred during the final Wisconsin stages. Two or three separate glacial periods are recognized from the morphology of the area. Instantaneous glaciation of a large area of the Labrador-Ungava Plateau probably initiated a continental ice sheet in northeastern North America at the onset of each glacial period. Also pub. in International Union of Geodesy and Geophysics, Association of Scientific Hydrology, 11th assembly report of proceedings 1958, v. 4, p. 372-86.

Holocene Deglaciation, Sea-Level Change, and the Emergence of the Windmill Islands, Budd Coast, Antarctica

1993 ◽  
Vol 40 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Ian D. Goodwin
Keyword(s):  
Sea Level ◽  
Late Pleistocene ◽  
Ice Sheet ◽  
Sea Level Change ◽  
Adélie Penguin ◽  
Adelie Penguin ◽  
Level Change ◽  
Isostatic Uplift ◽  
Uplift Rates ◽  
Windmill Islands

AbstractA Holocene deglaciation sequence for the Windmill Islands was determined from the 14C age of raised marine shorelines, lakebottom sediments, and Adelie penguin remains found in abandoned rookeries. A north-south gradient in the elevation of the upper marine limit was observed, with the highest marine limit (31-32 m) observed on Browning Peninsula and Hull Island at the southern edge of the islands. Correspondingly, the southern islands were found to have been deglaciated by 8000 (corr.) yr B.P. while the northern islands were deglaciated by 5500 (corr.) yr B.P. Isostatic uplift rates were calculated as 0.5 to 0.6 m/100 yr, with an estimated total uplift of around 53 m which indicates late Pleistocene ice sheet thicknesses of 200 and 400 m over the islands and adjacent Petersen Bank, respectively. The margin of the Late Pleistocene grounded ice sheet extended an estimated 8-15 km offshore which coincides with the location of the 200 m isobath.

scholarly journals The Effects of the Laurentide Ice Sheet on North American Climate during the Last Glacial Maximum

2008 ◽  
Vol 41 (2) ◽  
pp. 291-299 ◽  
Author(s):  
A. J. Broccoli ◽  
S. Manabe
Keyword(s):  
North America ◽  
Last Glacial Maximum ◽  
North American ◽  
Ice Sheet ◽  
Glacial Maximum ◽  
Laurentide Ice Sheet ◽  
Last Glacial ◽  
North American Climate ◽  
The Last Glacial Maximum ◽  
The Last Glacial

ABSTRACT A climate model, consisting of an atmospheric general circulation model coupled with a simple model of the oceanic mixed layer, is used to investigate the effects of the continental ice distribution of the last glacial maximum (LGM) on North American climate. This model has previously been used to simulate the LGM climate, producing temperature changes reasonably in agreement with paleoclimatic data. The LGM distribution of continental ice according to the maximum reconstruction of HUGHES et al. (1981) is used as input to the model. In response to the incorporation of the expanded continental ice of the LGM, the model produces major changes in the climate of North America. The ice sheet exerts an orographic effect on the tropospheric flow, resulting in a splitting of the midlatitude westerlies in all seasons but summer. Winter temperatures are greatly reduced over a wide region south of the Laurentide ice sheet, although summer cooling is less extensive. An area of reduced soil moisture develops in the interior of North America just south of the ice margin. At the same time, precipitation increases in a belt extending from the extreme southeastern portion of the ice sheet eastward into the North Atlantic. Some of these findings are similar to paleoclimatic inferences based on geological evidence.

scholarly journals Cosmogenic nuclide dating of the sediments of Bulmer Cavern: Implications for the uplift history of southern Northwest Nelson, South Island New Zealand

2021 ◽  
Author(s):  
◽  
Gavin Holden
Keyword(s):  
Late Miocene ◽  
Plate Boundary ◽  
Sedimentary Basins ◽  
Tectonic Activity ◽  
Published Data ◽  
Uplift Rate ◽  
Cosmogenic Nuclide ◽  
Alpine Fault ◽  
Uplift Rates ◽  
Rapid Uplift

<p>The landscape of Northwest Nelson shows evidence of significant tectonic activity since the inception of the Austro-Pacific plate boundary in the Eocene. Evidence of subsidence followed by rapid uplift from the Eocene to the late Miocene is preserved in the sedimentary basins of Northwest Nelson. However, the effects of erosion mean there is very little evidence of post-Miocene tectonic activity preserved in the Northwest Nelson area. This is a period of particular interest, because it coincides with the onset of rapid uplift along the Alpine Fault, which is located to the south, and the very sparse published data for this period suggest very low uplift rates compared to other areas close to the Alpine Fault.  Cosmogenic nuclide burial dating of sediments preserved in Bulmer Cavern, indicate an uplift rate of 0.13mm/a from the mid-Pliocene to the start of the Pleistocene and 0.067mm/a since the start of the Pleistocene.  The Pleistocene uplift rate is similar to other published uplift rates for this period from the northern parts of Northwest Nelson, suggesting that the whole of Northwest Nelson has experienced relative tectonic stability compared to other areas close to the Alpine Fault during this period. The mid-Pliocene uplift rate is possibly the first precisely constrained uplift rate in the area for this period, and suggests that there has been a progressive decrease in uplift rates from much higher rates in the late Miocene.</p>

scholarly journals Palimpsest tunnel valleys: evidence for relative timing of advances in an interlobate area of the Laurentide ice sheet

1999 ◽  
Vol 28 ◽  
pp. 47-52 ◽  
Author(s):  
Alan E. Kehew ◽  
Linda P. Nicks ◽  
W. Thomas Straw
Keyword(s):  
North America ◽  
Lake Michigan ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Great Lakes Region ◽  
Relative Timing ◽  
Outburst Flood ◽  
Flow Lines ◽  
Lake Michigan Lobe ◽  
East West

AbstractDuring retreat from the lateWisconsinan maximum advance in the Great Lakes region of North America, the Laurentide ice sheet margin became distinctly lobate. The Lake Michigan, Saginaw, and Huron—Erie lobes converged in southern Michigan and Indiana, U.S.A. to form a complex interlobate region. Some time after the glacial maximum, the Lake Michigan lobe advanced over landscapes previously formed by the Saginaw lobe. This can be explained by an asynchronous advance of the Lake Michigan lobe during a Saginaw lobe retreat or by an increase in size of the Lake Michigan lobe relative to the Saginaw lobe during a synchronous readvance.Cross-cutting relationships in southwestern Michigan, including palimpsest tunnel valleys, document the overriding of Saginaw lobe terrain. Deep, generally straight trenches parallel to glacial flow lines with hummocky, irregular sides and bottoms are interpreted as tunnel valleys. Saginaw lobe tunnel valleys trend northeast—southwest and Lake Michigan lobe tunnel valleys generally trend east—west.At some time after a Saginaw lobe retreat in southern Michigan, the drumlinized landscape was overridden by an advance of the Lake Michigan lobe to an ice-marginal position at the Tekonsha moraine. Saginaw lobe tunnel valleys in the overridden area were completely filled with ice and debris from the Saginaw lobe retreat at the time of the Lake Michigan lobe advance. Supraglacial and proglacial sediments were deposited over the buried valleys by the Lake Michigan lobe, sometimes by meltwater streams that flowed at high angles to the trends of the valleys. After entrenchment of the Kalamazoo River valley, probably by a subglacial outburst flood, short tributaries were cut nearly at right angles across and through the debris and ice within several buried Saginaw lobe tunnel valleys. After the retreat of the Lake Michigan lobe, subsequent melting of ice in the palimpsest tunnel valleys exhumed the valleys, creating the cross-cutting relationships with the Lake Michigan lobe deposits.

scholarly journals Cosmogenic nuclide dating of the sediments of Bulmer Cavern: Implications for the uplift history of southern Northwest Nelson, South Island New Zealand

2021 ◽  
Author(s):  
◽  
Gavin Holden
Keyword(s):  
Late Miocene ◽  
Plate Boundary ◽  
Sedimentary Basins ◽  
Tectonic Activity ◽  
Published Data ◽  
Uplift Rate ◽  
Cosmogenic Nuclide ◽  
Alpine Fault ◽  
Uplift Rates ◽  
Rapid Uplift

<p>The landscape of Northwest Nelson shows evidence of significant tectonic activity since the inception of the Austro-Pacific plate boundary in the Eocene. Evidence of subsidence followed by rapid uplift from the Eocene to the late Miocene is preserved in the sedimentary basins of Northwest Nelson. However, the effects of erosion mean there is very little evidence of post-Miocene tectonic activity preserved in the Northwest Nelson area. This is a period of particular interest, because it coincides with the onset of rapid uplift along the Alpine Fault, which is located to the south, and the very sparse published data for this period suggest very low uplift rates compared to other areas close to the Alpine Fault.  Cosmogenic nuclide burial dating of sediments preserved in Bulmer Cavern, indicate an uplift rate of 0.13mm/a from the mid-Pliocene to the start of the Pleistocene and 0.067mm/a since the start of the Pleistocene.  The Pleistocene uplift rate is similar to other published uplift rates for this period from the northern parts of Northwest Nelson, suggesting that the whole of Northwest Nelson has experienced relative tectonic stability compared to other areas close to the Alpine Fault during this period. The mid-Pliocene uplift rate is possibly the first precisely constrained uplift rate in the area for this period, and suggests that there has been a progressive decrease in uplift rates from much higher rates in the late Miocene.</p>

Prediction of decadal slope changes in Canada by glacial isostatic adjustment modellingThis article is one of a series of papers published in this Special Issue on the theme GEODESY.

2009 ◽  
Vol 46 (8) ◽  
pp. 587-595 ◽  
Author(s):  
Wouter van der Wal ◽  
Alexander Braun ◽  
Patrick Wu ◽  
Michael G. Sideris
Keyword(s):  
North America ◽  
Land Surface ◽  
Lake Michigan ◽  
Vertical Motion ◽  
Glacial Isostatic Adjustment ◽  
Uplift Rate ◽  
Isostatic Adjustment ◽  
Uplift Rates ◽  
The Difference ◽  
Differential Uplift

In Canada, glacial isostatic adjustment (GIA) is the dominant process to cause vertical motion of the land surface. A GIA model is presented herein that can be used to predict slope changes at given locations in North America where GIA is the primary cause for vertical motion. Uncertainty in Pleistocene ice cover and viscosity in the Earth’s mantle prevent one from picking a single GIA model from the literature to predict uplift rates in the region. Therefore, in this study, a range of mantle viscosity values as well as two different ice-loading histories are used in a forward model of the GIA process. The combination of viscosities and ice model that gives the best fit to recently available continuous and episodic GPS observations is assumed to provide the best prediction of slope changes in North America. This model can be used to quantify GIA-induced vertical deformation in local geomorphologic studies. We show that the predicted differential uplift rate in the Nelson River with respect to Lake Winnipeg reaches 1 mm/year over a 200 km distance using the model that best fits the GPS data whereas the ICE-5Gv1.2/VM2 model gives a slightly larger value. The difference in uplift rate between the northern and southern shore of Lake Michigan amounts up to 3 mm/year (slightly larger than the ICE-5Gv1.2/VM2 model), which could lead to a change in shorelines of tens of metres horizontally over a period of 100 years.

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