Holocene deltaic sedimentation along an emerging coast: Nastapoka River delta, eastern Hudson Bay, Quebec

2002 ◽  
Vol 39 (4) ◽  
pp. 505-518 ◽  
Author(s):  
Caroline Lavoie ◽  
Michel Allard ◽  
Philip R Hill
Keyword(s):  
River Delta ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Fluvial Erosion ◽  
Fine Grained ◽  
Isostatic Rebound ◽  
Geophysical Surveys ◽  
Deltaic Sedimentation ◽  
Forced Regression ◽  
Natural Laboratory

Eastern Hudson Bay is characterized by falling relative sea level as a result of post-glacial isostatic rebound, which makes the region a natural laboratory for rapid forced regression, where the evolution of deltaic systems and offshore sedimentation patterns can be studied. A multidisciplinary approach involving airphoto analysis, offshore geophysical surveys, sediment coring, and facies and diatom analyses was used in this study of the Nastapoka River delta. The delta has formed as a result of the fluvial erosion of emerged Quaternary sediments but is mainly subaqueous. Offshore, in the prodelta zone, the oldest deposits are glaciomarine, laid down when the ice front of the receding Laurentide ice sheet stood on the Nastapoka hills some 7700–6800 years BP. Lateral equivalents of this glaciomarine unit are presently exposed on land. The shallow-water platform of the delta shows a thin surficial unit of wave-worked sand that overlies fine-grained, deeper water deposits derived from erosion of clay soils in the river catchment a few centuries ago, probably during periods of intense thermokarst activity. As the isostatic uplift continues, the deltaic platform will gradually emerge and be incised by the river channel.

scholarly journals Late Wisconsinan Sedimentation in the Québec City Region: Evidence for Energetic Subaqueous Fan Deposition During Initial Deglaciation

2003 ◽  
Vol 55 (3) ◽  
pp. 257-273 ◽  
Author(s):  
Don Cummings ◽  
Serge Occhietti
Keyword(s):  
Slope Failure ◽  
Laurentide Ice Sheet ◽  
Quebec City ◽  
Coastal Zones ◽  
City Region ◽  
Fluvial Systems ◽  
Isostatic Rebound ◽  
South Shore ◽  
Forced Regression ◽  
Late Wisconsinan

Abstract In the St. Lawrence Valley just west of Québec City, initial deglaciation was accompanied by an energetic northward discharge of meltwater into a body of water, possibly subglacial, that was present in the axis of the valley. At Pointe Saint-Nicolas, a thick (> 35 m) ice-proximal sandy subaqueous fan was deposited during this event. The subaqueous fan is composed primarily of northwest-dipping turbidite sheets, with minor hyperconcentrated underflow channel fills and gravel-outwash deposits. By 11 200 14C BP, subaqueous fan sedimentation had stopped, and massive to rhythmically interbedded glaciomarine muds were being deposited. Introduction of muds into the basin promoted subaqueous slope failure and debris flowing locally. Between 10 950 and 10 800 14C BP, the Laurentide Ice Sheet readvanced southward onto the south shore, and deposited the subglacial St. Nicolas Till. With continued isostatic rebound and associated forced regression, tidal currents began to rework emergent coastal zones, and fluvial systems started to incise their valleys.

scholarly journals Evidence from 40Ar/39Ar Ages for a Churchill province source of ice-rafted amphiboles in Heinrich layer 2

1996 ◽  
Vol 42 (142) ◽  
pp. 440-446 ◽  
Author(s):  
Roberto H. Gwiazda ◽  
Sidney R. Hemming ◽  
Wallace S. Broecker ◽  
Tullis Onsttot ◽  
Chris Mueller
Keyword(s):  
North Atlantic ◽  
Drainage Basin ◽  
Ice Sheets ◽  
Bimodal Distribution ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Glacial Sediment ◽  
The North ◽  
Layer 2 ◽  
Eastern North Atlantic

Abstract40Ar/39Ar ages of most single ice-ratted amphiboles from Heinrich layer 2 (H2) from a core in the Labrador Sea, a core in the eastern North Atlantic and a core in the western North Atlantic range from 1600 to 2000 Ma. This range is identical to that for K/Ar ages from the Churchill province of the Canadian Shield that outcrops at Hudson Strait and forms the basement of the northern part of Hudson Bay. The ambient glacial sediment includes some younger and older grains derived from Paleozoic, Mesoproterozoic and Archean sources, but still the majority of the amphiboles have ages in the 1600–2000 Ma interval. The Ca/K ratios of these 1600–2000 Ma old amphiboles, however, have a bimodal distribution in contrast with the uniformity of the Ca/K ratios of H2 amphiboles. This indicates that 1600–2000 Ma old amphiboles of the ambient sediment were derived from an additional Early Proterozoic source besides Churchill province. In H2, Churchill-derived grains constitute 20–40% of the ice-rafted debris (IRD). The fraction in the ambient glacial sediment is 65–80%. Results presented here are consistent with the hypothesis that Heinrich events were produced by a sudden intensification of the iceberg discharge through Hudson Strait that mixed, in the North Atlantic, with icebergs that continued to calve from other ice sheets. The shift from mixed sources in the background sediment to a large dominance of Churchill province grains in H2 indicates that, even if calving of other ice sheets intensified during the Heinrich episode, the increase in the iceberg discharge via Hudson Strait from the Hudson Bay drainage basin of the Laurentide ice sheet was by far the largest.

scholarly journals Objective Reconstructions of the Late Wisconsinan Laurentide Ice Sheet and the Significance of Deformable Beds

2007 ◽  
Vol 39 (3) ◽  
pp. 229-238 ◽  
Author(s):  
D. A. Fisher ◽  
N. Reeh ◽  
K. Langley
Keyword(s):  
Yield Stress ◽  
Flow Direction ◽  
Three Dimensional ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Ice Streams ◽  
Ice Flow ◽  
Surface Slopes ◽  
Late Wisconsinan

ABSTRACT A three dimensional steady state plastic ice model; the present surface topography (on a 50 km grid); a recent concensus of the Late Wisconsinan maximum margin (PREST, 1984); and a simple map of ice yield stress are used to model the Laurentide Ice Sheet. A multi-domed, asymmetric reconstruction is computed without prior assumptions about flow lines. The effects of possible deforming beds are modelled by using the very low yield stress values suggested by MATHEWS (1974). Because of low yield stress (deforming beds) the model generates thin ice on the Prairies, Great Lakes area and, in one case, over Hudson Bay. Introduction of low yield stress (deformabie) regions also produces low surface slopes and abrupt ice flow direction changes. In certain circumstances large ice streams are generated along the boundaries between normal yield stress (non-deformable beds) and low yield stress ice (deformabie beds). Computer models are discussed in reference to the geologically-based reconstructions of SHILTS (1980) and DYKE ef al. (1982).

scholarly journals Simulating the Early Holocene demise of the Laurentide Ice Sheet with BISICLES (public trunk revision 3298)

2020 ◽  
Vol 13 (9) ◽  
pp. 4555-4577
Author(s):  
Ilkka S. O. Matero ◽  
Lauren J. Gregoire ◽  
Ruza F. Ivanovic
Keyword(s):  
Mass Balance ◽  
General Circulation ◽  
Ice Sheet ◽  
Circulation Model ◽  
Early Holocene ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
The North

Abstract. Simulating the demise of the Laurentide Ice Sheet covering Hudson Bay in the Early Holocene (10–7 ka) is important for understanding the role of accelerated changes in ice sheet topography and melt in the 8.2 ka event, a century long cooling of the Northern Hemisphere by several degrees. Freshwater released from the ice sheet through a surface mass balance instability (known as the saddle collapse) has been suggested as a major forcing for the 8.2 ka event, but the temporal evolution of this pulse has not been constrained. Dynamical ice loss and marine interactions could have significantly accelerated the ice sheet demise, but simulating such processes requires computationally expensive models that are difficult to configure and are often impractical for simulating past ice sheets. Here, we developed an ice sheet model setup for studying the Laurentide Ice Sheet's Hudson Bay saddle collapse and the associated meltwater pulse in unprecedented detail using the BISICLES ice sheet model, an efficient marine ice sheet model of the latest generation which is capable of refinement to kilometre-scale resolutions and higher-order ice flow physics. The setup draws on previous efforts to model the deglaciation of the North American Ice Sheet for initialising the ice sheet temperature, recent ice sheet reconstructions for developing the topography of the region and ice sheet, and output from a general circulation model for a representation of the climatic forcing. The modelled deglaciation is in agreement with the reconstructed extent of the ice sheet, and the associated meltwater pulse has realistic timing. Furthermore, the peak magnitude of the modelled meltwater equivalent (0.07–0.13 Sv) is compatible with geological estimates of freshwater discharge through the Hudson Strait. The results demonstrate that while improved representations of the glacial dynamics and marine interactions are key for correctly simulating the pattern of Early Holocene ice sheet retreat, surface mass balance introduces by far the most uncertainty. The new model configuration presented here provides future opportunities to quantify the range of plausible amplitudes and durations of a Hudson Bay ice saddle collapse meltwater pulse and its role in forcing the 8.2 ka event.

Frasnian-Famennian transition in western Thailand: conodonts, biofacies, eustatic changes, extinction

2019 ◽  
Vol 93 (3) ◽  
pp. 476-495 ◽  
Author(s):  
Norman M. Savage
Keyword(s):  
New Species ◽  
New Taxa ◽  
New Subspecies ◽  
Fine Grained ◽  
Extinction Event ◽  
Forced Regression ◽  
Possible Cause ◽  
Northwestern Thailand

AbstractThe biofacies of the Lower Palmatolepis rhenana Biozone to Palmatolepis triangularis Biozone in the Mae Sariang section, northwestern Thailand, are marked by alternations of Palmatolepis-dominated biofacies and Polygnathus-dominated biofacies related to fluctuations in seawater depth. Fine-grained limestone accumulated through the Lower Palmatolepis rhenana Biozone, Upper Palmatolepis rhenana Biozone, Palmatolepis linguiformis Biozone, Palmatolepis subperlobata Biozone, and Palmatolepis triangularis Biozone. A regression in the Upper rhenana Zone was followed by a recovery transgression that extended up through the linguiformis Zone. Conodont faunas increased until near the end of the linguiformis Zone, but in the overlying subperlobata Zone and triangularis Zone, conodont numbers dropped and most conodont species disappeared. It is possible the event coincides with a glacially forced regression, but there is no evidence of this in the section apart from a positive spike in δ13C. Another possible cause of the global marine extinction event is toxic levels of metals resulting from widespread volcanism. New taxa in this paper are Palmatolepis chaemensis new species, Palmatolepis thamensis new species, and Polygnathus tenellus surinensis new subspecies.UUID: http://zoobank.org/f2b55ba8-fe49-46f6-a2d5-bfd0208f1460

Dynamics of the Laurentide Ice Sheet in Hudson Bay, Canada

1990 ◽  
Vol 92 (1-2) ◽  
pp. 1-26 ◽  
Author(s):  
H.W Josenhans ◽  
J Zevenhuizen
Keyword(s):  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Hudson Bay

A relative sea-level history for Arviat, Nunavut, and implications for Laurentide Ice Sheet thickness west of Hudson Bay

2014 ◽  
Vol 82 (1) ◽  
pp. 185-197 ◽  
Author(s):  
Karen M. Simon ◽  
Thomas S. James ◽  
Donald L. Forbes ◽  
Alice M. Telka ◽  
Arthur S. Dyke ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Ice Sheet ◽  
Tidal Range ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Level Curve ◽  
Relative Sea Level ◽  
Vertical Land Motion ◽  
Crustal Uplift

AbstractThirty-six new and previously published radiocarbon dates constrain the relative sea-level history of Arviat on the west coast of Hudson Bay. As a result of glacial isostatic adjustment (GIA) following deglaciation, sea level fell rapidly from a high-stand of nearly 170 m elevation just after 8000 cal yr BP to 60 m elevation by the mid Holocene (~ 5200 cal yr BP). The rate of sea-level fall decreased in the mid and late Holocene, with sea level falling 30 m since 3000 cal yr BP. Several late Holocene sea-level measurements are interpreted to originate from the upper end of the tidal range and place tight constraints on sea level. A preliminary measurement of present-day vertical land motion obtained by repeat Global Positioning System (GPS) occupations indicates ongoing crustal uplift at Arviat of 9.3 ± 1.5 mm/yr, in close agreement with the crustal uplift rate inferred from the inferred sea-level curve. Predictions of numerical GIA models indicate that the new sea-level curve is best fit by a Laurentide Ice Sheet reconstruction with a last glacial maximum peak thickness of ~ 3.4 km. This is a 30–35% thickness reduction of the ICE-5G ice-sheet history west of Hudson Bay.

Slave River delta: geomorphology, sedimentology, and Holocene reconstruction

1988 ◽  
Vol 25 (12) ◽  
pp. 1990-2004 ◽  
Author(s):  
Sandy Vanderburgh ◽  
Derald G. Smith
Keyword(s):  
River Delta ◽  
Delta Front ◽  
Average Width ◽  
Sand Waves ◽  
Isostatic Rebound ◽  
Great Slave Lake ◽  
Sand Body ◽  
Fort Smith ◽  
River Rapids ◽  
Slave River Delta

The Holocene Slave River delta (8300 km2) is a long (170 km), narrow (42 km average width) alluvial sand body, which extends north from the Slave River rapids at Fort Smith to Great Slave Lake, Northwest Territories. The delta is flanked by the Talston and Tethul rivers and Canadian Shield to the east and by the Little Buffalo River to the west. Wave-associated sedimentary structures in lithostratigraphic logs from river cutbanks indicate that the sandy delta was wave influenced. Most of the logs (34) consist of three facies: basal laminated mud (unknown thickness), interbedded mud and sand (2.5 m), and planar-tabular ripple sets interbedded with cross-laminated to flat-bedded sand (3.0–14.5 m).Eleven radiocarbon-dated wood samples from river cutbanks were used to reconstruct the delta paleoshoreface and to calculate the rate of progradation, which averaged 20.7 m/year from 8070 BP to the present. In the same period isostatic rebound of the delta region relative to the Liard River delta averaged 12 cm/km (a total rebound of 48 m). The data were calculated normal to the retreating Laurentide ice front.From the surface to depths of 59 m, the subaerial and subaqueous delta front exhibits barrier islands, lagoons, offshore bars or sand waves, tensional cracks, slumps and pressure ridges. The barriers and offshore bars consist of medium grain-sized sand, whereas the slumps and pressure ridges are interpreted as mud.

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