scholarly journals A varve record of Lake Ojibway glaciolacustrine deposits from Lac Dasserat, northwestern Quebec, Canada

2016 ◽  
Author(s):  
G R Brooks
Keyword(s):  
Lake Ojibway

Cosmogenic10Be dating of raised shorelines constrains the timing of lake levels in the eastern Lake Agassiz-Ojibway basin

2017 ◽  
Vol 88 (2) ◽  
pp. 265-276 ◽  
Author(s):  
Pierre-Marc Godbout ◽  
Martin Roy ◽  
Jean J. Veillette ◽  
Joerg M. Schaefer
Keyword(s):  
Lake Level ◽  
Time Interval ◽  
Lake Levels ◽  
Lake Agassiz ◽  
Cosmogenic Isotopes ◽  
Exposure Dating ◽  
Group 3 ◽  
Lake Stage ◽  
Lake Ojibway

AbstractSurface exposure dating was applied to erosional shorelines associated with the Angliers lake level that marks an important stage of Lake Ojibway. The distribution of 1510Be ages from five sites shows a main group (10 samples) of coherent10Be ages yielding a mean age of 9.9±0.7 ka that assigns the development of this lake level to the early part of the Lake Ojibway history. A smaller group (3 samples) is part of a more scattered distribution of older10Be ages (with 2 outliers) that points to an inheritance of cosmogenic isotopes from a previous exposure, revealing an apparent mean age of 15.8±0.9 ka that is incompatible with the Ojibway inundation and the regional deglaciation. Our results provide the first direct10Be chronology on the sequence of lake levels in the Ojibway basin, which includes the lake stage presumably associated with the confluence and subsequent drainage of Lakes Agassiz and Ojibway. This study demonstrates the potential of this approach to date glacial lake shorelines and underlies the importance of obtaining additional chronological constraints on the Agassiz-Ojibway shoreline sequence to confidently assign a particular lake stage and/or lake-level drawdown to a specific time interval of the deglaciation.

A Late Pleistocene plant-bearing deposit in Currie Township, near Matheson, Ontario

1979 ◽  
Vol 16 (5) ◽  
pp. 1130-1136 ◽  
Author(s):  
W. E. Brereton ◽  
J. A. Elson
Keyword(s):  
River Basin ◽  
Late Pleistocene ◽  
Glacial Lake ◽  
Fossil Plants ◽  
Fossil Plant ◽  
James Bay ◽  
Plant Detritus ◽  
Lake Ojibway ◽  
Moose River ◽  
James Bay Lowlands

Two overburden test holes drilled to bedrock in Currie Township, southwest of Matheson, Ontario, penetrated stratified beds containing fossil plant detritus resting on an oxidized substrate, which are between two till sheets underlying glacial Lake Ojibway-Barlow varved clays. The fossil plants, chiefly mosses, represent an environment that is common in the region today, and are radiocarbon dated (GSC-2148) as older than 37000 years. The interglacial deposit is tentatively correlated with the Missinaibi Formation in the Moose River basin of the James Bay lowlands, probably of Sangamon age.

A model for the demise of large, glacial Lake Ojibway, Ontario and Quebec

2013 ◽  
Vol 50 (1) ◽  
pp. 105-121 ◽  
Author(s):  
Justin S. Stroup ◽  
Thomas V. Lowell ◽  
Andy Breckenridge
Keyword(s):  
Glacial Lake ◽  
Lake Ojibway

Postglacial paleoceanography of Hudson Bay: stratigraphic, microfaunal, and palynological evidence

1990 ◽  
Vol 27 (7) ◽  
pp. 946-963 ◽  
Author(s):  
Guy Bilodeau ◽  
Anne de Vernal ◽  
Claude Hillaire-Marcel ◽  
Heiner Josenhans
Keyword(s):  
Surface Waters ◽  
Latitudinal Gradient ◽  
Water Mass ◽  
Water Masses ◽  
Hudson Bay ◽  
Marine Invasion ◽  
Arctic Conditions ◽  
Pollen And Spores ◽  
Abundance And Diversity ◽  
Lake Ojibway

Cores containing representative sequences of postglacial sediments in northern and southern Hudson Bay were analyzed for their microfaunal (foraminifers and ostracods) and palynological (dinocysts, pollen, and spores) content in order to reconstruct the evolution of environments since the last glaciation.In southern Hudson Bay, the marine invasion of the Tyrrell Sea at ca. 8000 BP, following the Lake Ojibway episode, was accompanied by the development of an Arctic-type microflora and microfauna indicative of a dense seasonal sea-ice cover and stratified water masses. Shortly after 8000 BP, the establishment of subarctic conditions in surface waters was accompanied by more intense homogenization of water masses. Subarctic conditions have persisted throughout most of the postglacial interval despite a recent surface-water cooling.In northern Hudson Bay, micropaleontological and lithological data reveal a succession of proximal to distal glaciomarine environments characterized by low biogenic productivity, harsh Arctic conditions, and stratified water masses. An increase in dinocyst abundance and diversity, after 6000 BP, indicates the establishment of cool subarctic conditions in surface waters, while foraminifer assemblages suggest intensified mixing of water masses.The micropaleontological records of northern and southern Hudson Bay reveal a strong latitudinal gradient in biogenic productivity and water mass characteristics throughout the postglacial interval. "Interglacial" conditions, established in southern Hudson Bay very shortly after it was invaded by the sea, seem to have occurred much later in northern Hudson Bay.

The Nastapoka drift belt, eastern Hudson Bay: implications of a stillstand of the Quebec–Labrador ice margin in the Tyrrell Sea at 8 ka BP

2003 ◽  
Vol 40 (1) ◽  
pp. 65-76 ◽  
Author(s):  
Patrick Lajeunesse ◽  
Michel Allard
Keyword(s):  
Water Depth ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
James Bay ◽  
Western Margin ◽  
Submarine Fans ◽  
Grounding Line ◽  
Rapid Drop ◽  
Reduced Water ◽  
Lake Ojibway

During deglaciation of eastern Hudson Bay, the western margin of the Québec–Labrador sector of the Laurentide Ice Sheet came to a stillstand about 8 14C ka BP along the Nastapoka Hills, a series of topographic highs along the bay. These hills are the northward continuation of the eastern Hudson Bay cuesta system. It left a drift belt consisting of ice-contact submarine fans along the western slopes of the hills, small frontal moraines on hilltops, and grounding-line deposits on sills between the hills. Geomorphological, sedimentary, and radiometric evidence suggest that the stillstand responsible for deposition of the Nastapoka drift belt was either entirely or partly synchronous with the deposition of the Sakami moraine farther south. There was a period when these two morainic systems marked a continuous ice margin. These stillstands occurred due to reduction of ablation at the ice margin. In the Nastapoka Hills, ablation slowed down when the ice margin was anchored on higher relief and stood at a regional break of slope that grounded the ice margin and reduced water depth at the ice terminus, therefore, putting an end to intensive calving. In eastern James Bay and southeastern Hudson Bay, stabilization of the ice margin was caused by a reequilibrium of the ice terminus after a rapid drop of water level due to the drainage of Glacial Lake Ojibway. The new data improves the resolution of the position ice margin in eastern Hudson Bay at 8 ka BP.

Insights into the Connaught sequence of the Timiskaming varve series from Frederick House Lake, northeastern Ontario

2021 ◽  
Author(s):  
Gregory R. Brooks
Keyword(s):  
Mass Transport ◽  
Lake Ontario ◽  
Circumstantial Evidence ◽  
Glacial Lake ◽  
Core Samples ◽  
Acoustic Profile ◽  
Lake Ojibway

A sub-bottom acoustic profile survey encountered a mass transport deposit (MTD) bed, 5-7 m thick, interbedded within glaciolacustrine deposits of glacial Lake Ojibway at Frederick House Lake, Ontario. Analysis of the thickness patterns of rhythmic couplets in recovered core samples revealed that the Connaught sequence, the youngest of the Timiskaming varve series, immediately under- and overlie the MTD. Comparison to regional published varve series reveals two possible interpretations for the varve numbering. One, varve(v) 2066 to v2115, requires the inference of a 55 varve year (vyr) disconformity just below the Connaught sequence, while alternative numbering, <i>v2011a</i> to <i>v2060a</i> (<i>a</i> – alternative), extends continuously from older varves. Circumstantial evidence supporting the alternative numbering is: i) the uncertainty of applying a common 55 vyr disconformity to three varve series located up to 23 km apart and which otherwise exhibit closely matching thickness plots; ii) the lack of evidence of an erosive unconformity in the sub-bottom acoustic profiles from Frederick House Lake; and iii) the uncertain varve count within a key part of the Matagami series, located abut 300 km away and from which the 55 vyr disconformity is extrapolated. At Frederick House Lake, the alternative numbering indicates that the maximum position of the Cochrane ice advance and the Connaught varves may be, in effect, contemporary in age. More broadly, the alternative numbering indicates that the youngest known varve that formed before the terminal drainage of glacial Lake Ojibway is <i>v2074a</i> rather than v2129 in the original numbering.

Evidence of late glacial paleoseismicity from submarine landslide deposits within Lac Dasserat, northwestern Quebec, Canada

2016 ◽  
Vol 86 (2) ◽  
pp. 184-199 ◽  
Author(s):  
Gregory R. Brooks
Keyword(s):  
Ice Sheet ◽  
Late Glacial ◽  
Relative Strength ◽  
Submarine Landslide ◽  
Laurentide Ice Sheet ◽  
Glacial Lake ◽  
Event Horizons ◽  
Lake Ojibway

AbstractAn integrated seismo- and chronostratigraphic investigation at Lac Dasserat, northwestern Quebec, identified 74 separate failures within eight event horizons. Horizons E and B, and H and G have strong or moderately-strong multi-landslide signatures, respectively, composed of 11-23 failures, while horizons F, D, C, and A have minor landslide signatures consisting of a single or pair of deposit(s). Cores collected at six sites recovered glacial Lake Ojibway varve deposits that are interbedded with the event horizons. The correlation of the varves to the regional Timiskaming varve series allowed varve ages or ranges of varve ages to be determined for the event horizons. Horizons H, G, E, and B are interpreted to be evidence of paleoearthquakes with differing levels of interpretative confidence, based on the relative strength of the multi-landslide signatures, the correlation to other disturbed deposits of similar age in the region, and the lack or possibility of alternative aseismic mechanisms. The four interpreted paleoearthquakes occurred between 9770 ± 200 and 8470 ± 200 cal yr BP, when glacial Lake Ojibway was impounded behind the Laurentide Ice Sheet during deglaciation. They probably represent an elevated period of seismicity at deglaciation that was driven by crustal unloading.

Radiocarbon dates on peat and tree remains from James Bay area, subarctic Quebec

1979 ◽  
Vol 9 (1) ◽  
pp. 125-129 ◽  
Author(s):  
Jean-Claude Dionne
Keyword(s):  
Late Glacial ◽  
Glacial Lake ◽  
Before Present ◽  
James Bay ◽  
Radiocarbon Dates ◽  
Bay Area ◽  
Lake Ojibway ◽  
James Bay Lowlands

14C dates on peat and tree remains from the southern part of James Bay Lowlands, subarctic Quebec, indicate that forests and peatland conditions began at least 1000 years after the deglaciation of the area. Inception of forest and organic deposition in bogs varies within the main geological events of the late-glacial and postglacial times in the area: the drainage of glacial Lake Ojibway, the Tyrrell Sea transgression, and the emergence. The oldest age recorded for the beginning of peat deposition is 6890 ± 120 years before present (BP) at an elevation of 240 m and the youngest age is 3830 ± 120 years BP at an elevation of 60 m. A delay ranging from 400 to 900 years between forest occupation and the establishment of bog conditions is recorded.

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