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.

Pleistocene stratigraphy, paleopedology, and paleoecology of a multiple till sequence exposed on the Little Bear River, Western District of Mackenzie, N.W.T., Canada

1993 ◽  
Vol 30 (4) ◽  
pp. 851-866 ◽  
Author(s):  
O. L. Hughes ◽  
C. Tarnocai ◽  
C. E. Schweger
Keyword(s):  
Transition Zone ◽  
Ice Sheet ◽  
Climatic Conditions ◽  
Canadian Shield ◽  
Laurentide Ice Sheet ◽  
Spruce Forest ◽  
River Section ◽  
Valley Glacier ◽  
Bear River ◽  
Late Wisconsinan

The Little Bear River section lies in a transition zone between Mackenzie Lowland and Canyon Ranges of Mackenzie Mountains. Within the transition zone, the maximum extent of the Laurentide ice sheet overlaps the former extent of montane glaciers that emanated from the higher parts of Canyon Ranges or from the still higher Backbone Ranges to the southwest. Five montane tills, each with a paleosol developed in its upper part, indicate five separate glaciations during each of which a valley glacier emanating from the headwaters of Little Bear River extended eastward into the transition zone. The uppermost of the montane tills is overlain by boulder gravel containing rocks of Canadian Shield origin deposited by the Laurentide ice sheet.Solum and B horizon depths, red colours, and lack of leaching and cryoturbation indicate that although each successive interglacial interval was cooler than the preceding one, even the last of the intervals was warmer than the Holocene. Climatic conditions during one of the intervals inferred from the paleobotanic data, particularly spruce forest development, are consistent with conditions inferred from the associated paleosol.The uppermost of the montane tills is thought to correlate with till of Reid (Illinoian) age in central Yukon. The paleosol developed on that till is, accordingly, thought to correlate with the Diversion Creek paleosol developed on drift of Reid age. The Laurentide boulder gravel is assigned to a stade of Hungry Creek Glaciation of Late Wisconsinan age. The Laurentide ice sheet reached its apparent all-time western limit during the Hungry Creek Glaciation maximum.

scholarly journals Age Relationships of Laurentide and Montane Glaciations, Mackenzie Mountains, Northwest Territories

2007 ◽  
Vol 45 (1) ◽  
pp. 79-90 ◽  
Author(s):  
Alejandra Duk-Rodkin ◽  
Owen L. Hughes
Keyword(s):  
Northwest Territories ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Mountain Front ◽  
Bear River ◽  
Mackenzie Mountains ◽  
Late Wisconsinan

ABSTRACT The Mackenzie Mountains were glaciated repeatedly by large valley glaciers that emanated from the Backbone Ranges, and by much smaller valley glaciers that emanated from peaks in the Canyon Ranges. During the Late Wisconsinan the Laurentide Ice Sheet reached its all-time maximum position. The ice sheet pressed against the Canyon Ranges and moved up major valleys causing the diversion of mountain waters and organizing a complex meltwater system that drained across mountain interfluve areas towards the northwest. Two ages of moraines deposited by montane glaciers occur widely in the Mackenzie Mountains. Near the mountain front certain of the older moraines have been truncated by the Laurentide Ice Sheet, and others have been incised by meltwater streams emanating from the Laurentide ice margin, indicating that these older moraines predate the maximum Laurentide advance. Locally, certain of the younger montane moraines breach moraines and other ice marginal features of the Laurentide maximum, indicating that the younger montane glaciation post-dated the Laurentide maximum. Some large montane glaciers extended out from the mountains to merge with the retreating Laurentide Ice Sheet. There are several localities that display the age relationships between montane and Laurentide glaciations such as Dark Rock Creek, Durkan-Lukas Valley, Little Bear River and Katherine Creek. The older of the local montane glaciations is correlated tentatively with Reid Glaciation (lllinoian?) of central Yukon, and the younger with the Late Wisconsinan McConnell Glaciation. The Laurentide Glaciation is correlated with Hungry Creek Glaciation of Bonnet Plume Depression, which probably culminated about 30,000 years ago or somewhat later.

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.

Absence of Glaciation in Illinois during Marine Isotope Stages 3 through 5

1996 ◽  
Vol 46 (1) ◽  
pp. 19-26 ◽  
Author(s):  
B. Brandon Curry ◽  
Milan J. Pavich
Keyword(s):  
Oxygen Isotope ◽  
Late Stage ◽  
Lake Michigan ◽  
Early Stage ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Argillic Horizon ◽  
Late Wisconsinan ◽  
Lake Michigan Lobe

A10Be inventory and14C ages of material from a core from northernmost Illinois support previous interpretations that this area was ice free from ca. 155,000 to 25,000 yr ago. During much of this period, from about 155,000 to 55,000 yr ago, 10Be accumulated in the argillic horizon of the Sangamon Geosol. Wisconsinan loess, containing inherited 10Be, was deposited above the Sangamon Geosol from ca. 55,000 to 25,000 yr ago and was subsequently buried by late Wisconsinan till deposited by the Lake Michigan Lobe of the Laurentide Ice Sheet. The Sangamonian interglacial stage has been correlated narrowly to marine oxygen isotope substage 5e; our data indicate instead that the Sangamon Geosol developed during late stage 6, all of stages 5 and 4, and early stage 3.

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).

Genesis of carbonate till in the lee sides of Precambrian Shield uplands, Hemlo area, Ontario

1987 ◽  
Vol 24 (10) ◽  
pp. 2004-2015 ◽  
Author(s):  
Stephen R. Hicock
Keyword(s):  
Ice Sheet ◽  
Glacial Maximum ◽  
Laurentide Ice Sheet ◽  
The South ◽  
Precambrian Shield ◽  
Basal Zone ◽  
Compressive Flow ◽  
Late Wisconsinan ◽  
Basal Till

Near Hemlo, Ontario, highly calcareous till is confined to areas located downglacier from Precambrian uplands, at least 150 km from the Paleozoic–Precambrian boundary. It comprises subglacial meltout till between lodgment tills, and the calcareous package overlies noncalcareous basal till (not studied) and underlies noncalcareous supraglacial meltout till. The tills can be distinguished by textural, carbonate, and clast compositions. Glaciotectonic deformations, stone fabrics and striae, and stone provenance from the tills, as well as erosional and depositional landforms, indicate that ice advanced to the south–southwest across bedrock contacts and over Precambrian uplands.Deposition of all five tills can be explained with one glacial event. As the Late Wisconsinan margin of the Laurentide ice sheet advanced against uplands about 20 km northeast of Hemlo it experienced compressive flow while depositing the non calcareous basal till. Upshearing of stoss-side local debris high into the ice also occurred as englacial ice overrode the slowed basal zone. Once over the upland, englacial ice assumed extending flow, and downshearing of distal debris, which was deposited as calcareous lodgment till on the lee sides of uplands. After the glacial maximum, the glacier ceased internal movement and subglacial meltout till was laid down. A late reactivation of the ice deposited the upper lodgment till and final stagnation formed the supraglacial meltout till.

Laurentide and montane glaciation along the Rocky Mountain Foothills of northeastern British Columbia

2007 ◽  
Vol 44 (4) ◽  
pp. 445-457 ◽  
Author(s):  
Jan M Bednarski ◽  
I Rod Smith
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Rocky Mountain ◽  
Laurentide Ice Sheet ◽  
Cosmogenic Dating ◽  
Surficial Geology ◽  
Continental Divide ◽  
Mountain Front ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

Mapping the surficial geology of the Trutch map area (NTS 94G) provides new data on the timing of continental and montane glaciations along the Foothills of northeastern British Columbia. Striated surfaces on mountain crests were dated to the Late Wisconsinan substage by cosmogenic dating. The striations were produced by eastward-flowing ice emanating from the region of the Continental Divide. This ice was thick enough to cross the main ranges and overtop the Rocky Mountain Foothill summits at 2000 m above sea level (asl). It is argued here that such a flow, unhindered by topography, could only have been produced by the Cordilleran Ice Sheet and not by local cirque glaciation. During this time, the Cordilleran Ice Sheet dispersed limestone and schist erratics of western provenance onto the plains beyond the mountain front. Conversely, the Laurentide Ice Sheet did not reach its western limit in the Foothills until after Cordilleran ice retreated from the area. During its maximum, the Laurentide ice penetrated the mountain valleys up to 17 km west of the mountain front, and deposited crystalline erratics from the Canadian Shield as high as 1588 m asl along the Foothills. In some valleys a smaller montane advance followed the retreat of the Laurentide Ice Sheet.

Late Pleistocene depositional systems of Metropolitan Toronto and their engineering and glacial geological significance

1987 ◽  
Vol 24 (5) ◽  
pp. 1009-1021 ◽  
Author(s):  
N. Eyles
Keyword(s):  
Late Pleistocene ◽  
Cross Sections ◽  
Laurentide Ice Sheet ◽  
Drainage Network ◽  
Glacial History ◽  
Late Tertiary ◽  
History Of ◽  
Depositional Systems ◽  
Late Wisconsinan ◽  
Glacial Complex

The municipality of Metropolitan Toronto (area 480 km2, population 2.15 million) is centrally located on the Late Pleistocene sedimentary infill of the Laurentian Channel, a broad bedrock low up to 115 km wide connecting the Huron and Ontario basins. This channel forms part of a relict (late Tertiary?) drainage network (the Laurentian River) modified by Pleistocene glacial erosion and infilled by over 100 m of glacial and interglacial sediments. The subsurface stratigraphy of the channel fill below Metropolitan Toronto has been established from many different data sources and is depicted, in this paper, as a series of cross sections with a total length of nearly 105 km.The subsurface stratigraphy has been divided, provisionally, into five depositional complexes, which have been mapped in the subsurface along several transects. These are (1) a glacial complex of Illinoian (?) age, (2) a lacustrine complex of Sangamon Interglacial and earliest Wisconsinan sediments (120 000 – 75 000 BP?), (3) a glaciolacustrine – lacustrine complex spanning the Early and Mid-Wisconsinan (75 000 – 30 000 BP?), (4) a Late Wisconsinan (> 30 000 BP) glacial complex, and (5) a postglacial lacustrine complex (ca. 12 000 BP).The data presented in this paper are significant for applied geological investigations in the heavily urbanized Toronto area and provide new insights into the glacial history of the Ontario Basin, in particular the regional extent of the Laurentide Ice Sheet margin prior to the Late Wisconsinan.

Sign in / Sign up

Export Citation Format

Share Document