scholarly journals Late Quaternary deglaciation of Prince William Sound, Alaska

2021 ◽  
pp. 1-20
Author(s):  
Peter J. Haeussler ◽  
Ari Matmon ◽  
Maurice Arnold ◽  
Georges Aumaître ◽  
Didier Bourlès ◽  
...  
Keyword(s):  
Sea Level ◽  
North Pacific ◽  
Late Quaternary ◽  
North Pacific Ocean ◽  
Ice Sheets ◽  
Prince William Sound ◽  
Flow Paths ◽  
Ice Flow ◽  
Cordilleran Ice Sheet ◽  
Exposure Ages

Abstract To understand the timing of deglaciation of the northernmost marine-terminating glaciers of the Cordilleran Ice Sheet (CIS), we obtained 26 10Be surface-exposure ages from glacially scoured bedrock surfaces in Prince William Sound (PWS), Alaska. We sampled six elevation transects between sea level and 620 m and spanning a distance of 14 to 70 km along ice flow paths. Most transect age–elevation patterns could not be explained by a simple model of thinning ice; the patterns provide evidence for lingering ice cover and possible inheritance. A reliable set of 20 ages ranges between 17.4 ± 2.0 and 11.6 ± 2.8 ka and indicates ice receded from northwestern PWS around 14.3 ± 1.6 ka, thinned at a rate of ~120–160 m/ka, and retreated from sea-level sites at 12.9 ± 1.1 ka at a rate of 20 m/yr. The retreat rate likely slowed as glaciers retreated into northern PWS. These results are consistent with the growing body of reported deglacial constraints on collapse of ice sheets along the Alaska margin indicating collapse of the CIS soon after 17 ka. These data are consistent with paleotemperature data indicating that a warming North Pacific Ocean caused catastrophic collapse of this part of the CIS.

Time of Maximum Late Wisconsin Glaciation, West Coast of Canada

1990 ◽  
Vol 34 (3) ◽  
pp. 282-295 ◽  
Author(s):  
Bertrand Blaise ◽  
John J. Clague ◽  
Rolf W. Mathewes
Keyword(s):  
West Coast ◽  
North Pacific ◽  
Deep Sea ◽  
North Pacific Ocean ◽  
Ice Sheet ◽  
Late Glacial ◽  
Western Margin ◽  
The Core ◽  
Queen Charlotte Islands ◽  
Cordilleran Ice Sheet

AbstractNew data from a deep-sea core in the eastern North Pacific Ocean indicate that the western margin of the Late Wisconsin Cordilleran Ice Sheet began to retreat from its maximum position after 15,600 yr B.P. Ice-rafted detritus is present in the core below the 15,600 yr B.P. level and was deposited while lobes of the Cordilleran Ice Sheet advanced across the continental shelf in Queen Charlotte Sound, Hecate Strait, and Dixon Entrance. The core data are complemented by stratigraphic evidence and radiocarbon ages from Quaternary exposures bordering Hecate Strait and Dixon Entrance. These indicate that piedmont lobes reached the east and north shores of Graham Island (part of the Queen Charlotte Islands) between about 23,000 and 21,000 yr B.P. Sometime thereafter, but before 15,000–16,000 yr B.P., these glaciers achieved their greatest Late Wisconsin extent. Radiocarbon ages of late-glacial and postglacial sediments from Queen Charlotte Sound, Hecate Strait, and adjacent land areas show that deglaciation began in these areas before 15,000 yr B.P. and that the shelf was completely free of ice by 13,000 yr B.P.

Interannual Sea Level Variability in the North Pacific Ocean and Its Mechanisms

2010 ◽  
Vol 53 (1) ◽  
pp. 54-63 ◽  
Author(s):  
Yong-Chui ZHANG ◽  
Li-Feng ZHANG ◽  
Ye-Gui WANG
Keyword(s):  
Pacific Ocean ◽  
Sea Level ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Sea Level Variability ◽  
The North ◽  
The North Pacific

scholarly journals Increased West Antarctic ice discharge and East Antarctic stability over the last seven years

2017 ◽  
Author(s):  
Alex S. Gardner ◽  
Geir Moholdt ◽  
Ted Scambos ◽  
Mark Fahnstock ◽  
Stefan Ligtenberg ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Synthetic Aperture ◽  
Direct Role ◽  
Ice Flow ◽  
West Antarctic ◽  
Landsat 7 ◽  
Ice Velocity

Abstract. Ice discharge from large ice sheets plays a direct role in determining rates of sea level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 & 8 imagery spanning 2013–2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous changes in ice flow since ~ 2008. The new mapping provides complete coastal and inland coverage of ice velocity with a mean error of

Late Quaternary climate variability as recorded by micropalaeontological diatom data and geochemical data in the western Ross Sea, Antarctica

2013 ◽  
Vol 25 (6) ◽  
pp. 804-820 ◽  
Author(s):  
R. Tolotti ◽  
C. Salvi ◽  
G. Salvi ◽  
M.C. Bonci
Keyword(s):  
Continental Slope ◽  
Ross Sea ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Geochemical Data ◽  
Flow Paths ◽  
Ice Flow ◽  
Quaternary Climate ◽  
History Of ◽  
Geochemical Analyses

AbstractCores acquired from the Ross Sea continental shelf and continental slope during the XXX Italian Programma Nazionale di Ricerche in Antartide (PNRA) were analysed and yielded interesting micropalaeontological, biostratigraphic diatom results and palaeoceanographic implications. These multi-proxy analyses enabled us to reconstruct the glacial/deglacial history of this sector of the Ross embayment over the last 40 000 years, advancing our understanding of the Last Glacial Maximum (LGM) environmental and sedimentological processes linked to the Ross Sea ice sheet/ice shelf fluctuations in a basin and continental-slope environment, and allowed us to measure some of the palaeoceanographic dynamics. The central sector of the Ross Sea and part of its coast (south of the Drygalski Ice Tongue) enjoyed open marine conditions in the pre-LGM era (27 500–24 000 years bp). The retreat of the ice sheet could have been influenced by a southward shift of a branch of the Ross gyre, which triggered early deglaciation at c. 18 600 cal bp with a significant Modified Circumpolar Deep Water inflow over the continental slope at c. 14 380 cal BP. We assume that a lack of depositional material in each core, although at different times, represents a hiatus. Other than problems in core collection, this could be due to the onset of modern oceanographic conditions, with strong gravity currents and strong High Salinity Shelf Water exportation. Moreover, we presume that improvements in biostratigraphy, study of reworked diatom taxa, and lithological and geochemical analyses will provide important constraints for the reconstruction of the LGM grounding line, ice-flow lines and ice-flow paths and an interesting tool for reconstructing palaeo-sub-bottom currents in this sector of the Ross embayment.

Growth rate of the Laurentide Ice Sheet and sea Level Lowering (with Emphasis on the 115,000 BP Sea Level Low)

1976 ◽  
Vol 6 (2) ◽  
pp. 167-183 ◽  
Author(s):  
J.T. Andrews ◽  
M.A.W. Mahaffy
Keyword(s):  
Sea Level ◽  
Three Dimensional ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Baffin Island ◽  
Optimum Conditions ◽  
Ice Flow ◽  
Rapid Fall ◽  
Level Lowering

A physically plausible three-dimensional numerical ice flow model is used to examine the rate at which the Laurentide Ice Sheet could spread and thicken using as input likely values for the rate of fall of snowline and the amount of net mass balance over the growing ice sheet. This provides then both a test of the hypothesis of “instantaneous glacierization” and of the suggested rapid fall of world sea level to between −20 and −70 m below present at 115,000 BP. Two experiments are described: The first terminated after 10,050 years of model run with ice sheets centered over Labrador-Ungava and Baffin Island with a total volume of 3.0 × 106 km3 of ice, whereas the second was completed after 10,000 years and resulted in a significantly larger ice sheet (still with two main centers) with a volume of 7.78 × 106 km3 of ice. This latter figure is equivalent to the mass required to lower world sea level by 19.4 m. Our results indicate that large ice sheets can develop in about 10,000 years under optimum conditions.

scholarly journals Steric Sea Level Change in the Northern Seas

2007 ◽  
Vol 20 (3) ◽  
pp. 403-417 ◽  
Author(s):  
Michael Steele ◽  
Wendy Ermold
Keyword(s):  
Arctic Ocean ◽  
Sea Level ◽  
North Atlantic ◽  
North Pacific ◽  
North Atlantic Ocean ◽  
North Pacific Ocean ◽  
Steric Height ◽  
The North ◽  
Flow Through ◽  
The North Atlantic

Abstract Ocean temperature and salinity data over the period 1950–2000 in the Northern Seas, defined here as the North Atlantic Ocean (north of 50°N), North Pacific Ocean (north of 40°N), and Arctic Oceans, are combined to diagnose the steric (i.e., density) contribution to sea level variation. The individual contributions to steric height from temperature (thermosteric height) and salinity (halosteric height) are also analyzed. It is found that during 1950–2000, steric height rose over the study’s domain, mostly as a result of halosteric increases (i.e., freshening). Over a shorter time period (late 1960s to early 1990s) during which climate indices changed dramatically, steric height gradients near the Nordic Seas minimum were reduced by 18%–32%. It is speculated that this may be associated with a local slowing of both the Meridional Overturning Circulation and the southward flow through Fram Strait. However, steric height increases in the North Pacific Ocean during this time imply a possible acceleration of flow through the poorly measured Canadian Arctic. Evidence that the Great Salinity Anomaly of the late 1960s and 1970s had two distinct Arctic Ocean sources is also found: a late 1960s export of sea ice, and a delayed but more sustained 1970s export of liquid (ocean) freshwater. A simple calculation indicates that these Arctic Ocean freshwater sources were not sufficient to create the 1970s freshening observed in the North Atlantic Ocean.

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