Glacial geology of the Torngat Mountains, Labrador

1988 ◽  
Vol 25 (8) ◽  
pp. 1184-1198 ◽  
Author(s):  
Peter U. Clark
Keyword(s):  
Soil Profile ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Glacial Geology ◽  
Coastal Regions ◽  
Radiocarbon Dates ◽  
Areal Distribution ◽  
Profile Development

Two late Quaternary alloformations are identifed throughout the Torngat Mountains by degree of soil profile development in till with a granitic composition, morphologic expression of deposits, and their relative areal distribution. The two alloformations are interpreted to represent two, successively limited glaciations of the Torngat Mountains by the Laurentide Ice Sheet. Deposits of the Shoal Cove Alloformation mantle hillslopes distal to deposits of the younger Saglek Alloformation. Deposits are primarily soliflucted till found around coastal regions. Soils developed in till of the Shoal Cove Alloformation are characterized by well-expressed Bw horizons ≥ 19 cm thick. Deposits of the younger Saglek Alloformation are characterized by prominent, well-preserved moraines, outwash fan surfaces, and ice-marginal channels. Soils described in till are poorly developed, with A horizons directly overlying Cox horizons, or separated from Cox horizons by thin, transitional (AC, CA) horizons or poorly expressed Bw horizons. During deposition of this alloformation, the Laurentide Ice Sheet was confined to major valleys and fiords, leaving large areas of the mountains ice free. Old radiocarbon dates on shells from diamictons on the Iron Strand coast do not provide a unique age for glacial events on the Labrador coast. Age of marine limit on the coast suggests deglaciation from the event depositing the Saglek Alloformation began 9 000 – 10 000 years BP.

Late Tertiary to late Quaternary record in the Mackenzie Mountains, Northwest Territories, Canada: stratigraphy, paleosols, paleomagnetism, and chlorine - 36

1996 ◽  
Vol 33 (6) ◽  
pp. 875-895 ◽  
Author(s):  
A. Duk-Rodkin ◽  
R. W. Barendregt ◽  
C. Tarnocai ◽  
F. M. Phillips
Keyword(s):  
Late Quaternary ◽  
Ice Sheet ◽  
Climatic Conditions ◽  
Unconsolidated Sediments ◽  
Laurentide Ice Sheet ◽  
Stratigraphic Sequence ◽  
Late Tertiary ◽  
Mackenzie Mountains ◽  
Late Wisconsinan ◽  
Stratigraphic Succession

A stratigraphic sequence of unconsolidated sediments ranging in age from Late Pliocene to Late Pleistocene is recorded in the Canyon Ranges of the Mackenzie Mountains. Three of the sections (Katherine Creek, Little Bear River, and Inlin Brook) expose bedrock and Tertiary gravel overlain by colluvium and a multiple till sequence of montane origin, separated by paleosols and capped by a till of Laurentide origin. The sections are correlated on the basis of lithology, paleosol development, paleomagnetism, and chlorine dating of surface boulder erratics. A formal stratigraphic nomenclature is proposed for the deposits of this region. The sequence of glacial tills separated by paleosols reflects a long record of glacial–interglacial cycles. Soil properties from the oldest paleosol to modern soil show a general decrease in the degree of soil development, suggesting a progressive deterioration of interglacial climatic conditions. A normal–reverse–normal sequence of remanent magnetization was determined within the stratigraphic succession and assigned to the Gauss–Matuyama–Brunhes chrons, respectively. A Gauss age was assigned to the basal colluvium, an early Matuyama age (including Olduvai) to the first two tills, and a Brunhes age to the last three tills. Laurentide deposits are of Late Wisconsinan age and are restricted to the uppermost part of the stratigraphic succession. Chlorine dates for surface boulders place the all-time limit of the Laurentide Ice Sheet at about 30 ka. The Late Wisconsinan Laurentide Ice Sheet was the only continental ice to reach the Mackenzie and Richardson mountains of the northern Cordillera.

The glacial geology of northeastern Ellesmere Island, N.W.T., Canada

1978 ◽  
Vol 15 (4) ◽  
pp. 603-617 ◽  
Author(s):  
John England
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ellesmere Island ◽  
Glacial Geology ◽  
Radiocarbon Dates ◽  
Previous Evidence ◽  
Marine Deposits ◽  
Last Glaciation ◽  
Distal Side ◽  
Stratigraphic Boundary

Thirty-five radiocarbon dates associated with former ice sheet margins and raised marine deposits are presented from northeastern Ellesmere Island. Along the southern margin of Hazen Plateau, and in inner Archer Fiord, a prominent morpho-stratigraphic boundary is marked by the Hazen Moraines. These moraines represent a restricted ice advance during the last glaciation and date ca. 8130 ± 200 BP. On the immediate distal side of the Hazen Moraines, eastward for 100 km towards northwestern Greenland, the majority of dates on marine limits show synchronous emergence beginning ca. 7500 BP. This zone of synchronous emergence is considered to represent an ice-free corridor isostatically unloaded between the margins of the receding Greenland and Ellesmere island ice sheets.A more widespread till, above and beyond the Hazen Moraines, extends out of Archer Fiord–Lady Franklin Bay to Robeson and Kennedy channels. This maximum ice advance is considered to predate the last glaciation on the basis of 14C and amino acid dates from ice-marginal deposits; however, alternative interpretations of the data are presented. Previous evidence suggesting an older advance of the Greenland Ice Sheet onto this coastline is confirmed. Several glaciers in the area are presently at their maximum postglacial positions.

Late Quaternary (Stage 2 and 3) Meltwater and Heinrich Events, Northwest Labrador Sea

1994 ◽  
Vol 41 (1) ◽  
pp. 26-34 ◽  
Author(s):  
John T. Andrews ◽  
Helmut Erlenkeuser ◽  
Katherine Tedesco ◽  
Ali E. Aksu ◽  
A.J.Timothy Jull
Keyword(s):  
North Atlantic ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Labrador Sea ◽  
Near Surface ◽  
Heinrich Events ◽  
Eastern Margin ◽  
Detrital Carbonate

AbstractTwo major meltwater events are documented in cores from the NW Labrador Sea. One occurred ca. 20,000 14C yr B.P. in association with deposition of a major detrital carbonate unit. Both prior to and after this event, δ18O values of near-surface planktonic foraminifera were 4.5%, indicating fully enriched glacial values. A younger event (ca. 14,000 14 C yr B.P.) is characterized by a dramatic change in δ18O from 4.5 to 2.0% and coincided with the retreat of ice from the outer SE Baffin Shelf, possibly into Hudson Strait. These meltwater events coincide with Heinrich (H) layers 1 and 2 from North Atlantic sediments. The 14,000 14C yr B.P. meltwater event indicates that the eastern margin of the Laurentide Ice Sheet also underwent rapid retreat at approximately the same time as other ice sheet margins around the NE North Atlantic. A third major detrital carbonate event at the base of HU87-033-009, possibly correlative with Heinrich layer 3, occurred ca. 33,960 ± 675 14 C yr B.P.; however, this is older than the accepted date for H-3 of 27,000 14C yr B.P. and may be H-4.

Surface exposure dating of the Pierre Sublobe of the James Lobe, Laurentide Ice Sheet

2020 ◽  
Vol 97 ◽  
pp. 88-98
Author(s):  
Stephanie L. Heath ◽  
Thomas V. Lowell ◽  
Brenda L. Hall
Keyword(s):  
Late Quaternary ◽  
Ice Sheet ◽  
Age Dating ◽  
Laurentide Ice Sheet ◽  
Des Moines Lobe ◽  
Exposure Dating ◽  
Des Moines ◽  
Contrast Exposure ◽  
Ice Sheet Dynamics ◽  
Exposure Ages

AbstractThe Laurentide Ice Sheet of the last glacial period terminated in several lobes along its southern margin. The timing of maximum extent may have varied among the terminal lobes owing to internal ice sheet dynamics and spatially variable external controls. Some terminal ice lobes, such as the westernmost James Lobe, remain poorly dated. To determine the timing of maximum ice extent in this key location, we have mapped glacial deposits left by the Pierre Sublobe in South Dakota and applied 10Be surface exposure age dating on boulders on moraine ridges associated with three distinct late Quaternary glacial drifts. The oldest and most extensive “Tazewell” drift produced variable 10Be surface exposure ages spanning 20–7 ka; the large range is likely attributable to moraine degradation and subsequent boulder exhumation. The oldest ages of about 20 ka are probably limiting minimum ages for the Tazewell moraine surfaces. By contrast, exposure ages of the youngest “Mankato” drift of the easternmost Pierre Sublobe tightly cluster at about 16 ka. This age for the Pierre Sublobe is consistent with the nearby Des Moines Lobe, suggesting both acted together.

Ice-flow patterns and glacial transport in the eastern Hudson Bay region: implications for the late Quaternary dynamics of the Laurentide Ice Sheet

1995 ◽  
Vol 32 (12) ◽  
pp. 2057-2070 ◽  
Author(s):  
Michel Parent ◽  
Serge J. Paradis ◽  
Éric Boisvert
Keyword(s):  
Compositional Data ◽  
Late Quaternary ◽  
Regional Distribution ◽  
Ice Sheet ◽  
Glacial Maximum ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Ice Flow ◽  
Flow Phase ◽  
Late Wisconsinan

Recent field surveys in the eastern Hudson Bay region have led to the discovery of regional ice-flow sequences that require a significant reassessment of the late Quaternary dynamics of the Laurentide Ice Sheet. Two regional ice-flow phases can be recognized from till compositional data and from crosscutting relationships observed on striated bedrock surfaces: the oldest is directed toward the northwest and north-northwest, while the youngest is directed toward the west and includes a late-glacial deflection toward the southwest. The wide regional distribution of striae formed during the early northwestward glacial movement together with the recognition of palimpsest glacial dispersal trains associated with this phase suggest that it was a long-lived, time-transgressive regional event. The ensuing glacial movement is a regionally dominant westward ice-flow phase during which several large glacial dispersal trains were formed downglacier from distinctive bedrock sources. The largest of these trains extends westward over a distance of 120 km from Lac à l'Eau Claire to Hudson Bay. Regional glacial transport data as well as glacial and deglacial landforms indicate that this was a long-lived glacial phase, likely lasting throughout the Late Wisconsinan glacial maximum and until déglaciation about 8000 BP. The erosional and depositional record of the northwestward ice-flow event is quite comparable to that of the ensuing glacial phase, and it is thus thought to represent the Early Wisconsinan glacial maximum. In view of the large regional extent of the northwestward ice-flow phase, it must postdate the early buildup of the ice sheet. Along the southeastern Hudson Bay coast, the Late Wisconsinan westward glacial movement was followed by a southwestward deflection that was likely caused by glacial streaming prior to 8000 BP in James Bay, in response to calving and surging into Glacial Lake Ojibway.

scholarly journals Late Quaternary stratigraphy, chronology, and depositional processes on the slope of S.E. Baffin Island, detrital carbonate and Heinrich events: Implications for onshore glacial history

2002 ◽  
Vol 52 (1) ◽  
pp. 91-105 ◽  
Author(s):  
John T. Andrews ◽  
M. Kirby ◽  
Anne E. Jennings ◽  
D. C. Barber
Keyword(s):  
North Atlantic ◽  
Late Quaternary ◽  
Sediment Accumulation ◽  
Ice Sheet ◽  
Turbidity Currents ◽  
Baffin Island ◽  
Radiocarbon Dates ◽  
Heinrich Events ◽  
Depositional Processes ◽  
Detrital Carbonate

AbstractIn order to describe ice sheet/ocean interactions at the NE margin of the Laurentide Ice Sheet over 40 radiocarbon dates have been obtained on foraminifera from nine, 2.5 to 11 m piston cores from the slope of SE Baffin Island. The cores were collected off Cumberland Sound and north of Hudson Straitfrom 750 to 1 510 m waterdepth. Rates of sediment accumulation varied between 20 and 40 cm/ky. Six cores contain high-resolution records of events during Marine Isotope Stage (MIS) 2 and parts of 1 and 3, whereas three cores have core top dates of ≥30 ka and thus provide information on MIS 3 and possibly 4/5. The cores include three main facies: Lithofacies A - yellowish/buff detrital carbonate-rich sediment, also referred to as Detrital Carbonate (DC-) events; Lithofacies B - olive-green detrital carbonate-poor sediment; and Lithofacies C - a black sedimentary unit. The lithofacies represent changes in glacial sources, ice sheet proximity, and processes of deposition. We conclude that there are DC- events correlative with Heinrich events H-1, H- 2, and H-4 in the North Atlantic; however, we find no compelling evidence for a DC-layer during H-3 (ca. 27 ± ka). There are three to four distinct DC- events after H-4 (ca.35 ± ka) but their exact ages are difficult to determine. Grain-size spectra and X-radiographs show that the DC-sediments are stratified to massive silty-clays with little sand, but generally have higher sand percentages at the base. DC-layers were deposited in part from turbidity currents, melting of icebergs, and rain-out of fine-grained silts and clays. In contrast, ice distal sediments in the eastern North Atlantic recorded H-events as an abrupt increase in ice rafted sand-size particles. In our study area, H-layer thicknesses vary from 0 and 70 cm for H-1 and 20 to 90 cm for H-2; H-4 is ≥60 to 100 cm thick. Over the total length of our records, the sedimentary conditions have been dominated by hemipelagic deposition (lithofacies B), implying that those times when ice reached the shelf (lithofacies A and C) have been short.

A reinterpretation of glacial and marine limits around the northwestern Laurentide Ice Sheet

1987 ◽  
Vol 24 (4) ◽  
pp. 591-601 ◽  
Author(s):  
Arthur S. Dyke
Keyword(s):  
Sea Level ◽  
East Coast ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Ice Shelf ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Banks Island ◽  
History Of ◽  
Late Wisconsinan

Seven new radiocarbon dates pertaining to deglaciation of northern Prince of Wales Island place the margin of the Laurentide Ice Sheet on the island by 11 000 BP. This requires a revision of the proposed age for the Viscount Melville Sound Ice Shelf of 10 300 – 9880 BP. A revised age of 11 300 – 11 000 BP is suggested.The new dates also require revisions of the proposed Wisconsinan and Holocene history of Banks Island. Shells thought to have been thrust onshore to an elevation of 88 m by the ice shelf on northern Banks Island after 10 600 BP are reinterpreted as undisturbed postglacial marine shells recording a relative sea level of 88 m or more. This, in turn, suggests that the East Coast Sea and Jesse Till are of Late Wisconsinan rather than Early Wisconsinan age and that the Late Wisconsinan glacial limit on Banks Island as figured on the 1968 Glacial Map of Canada, rather than on recent revisions, is essentially correct.

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