Paleomagnetism of Quaternary and late Tertiary sediments on Mokowan Butte, southwestern Alberta

1991 ◽  
Vol 28 (12) ◽  
pp. 1956-1964 ◽  
Author(s):  
R. W. Barendregt ◽  
E. Irving ◽  
E. T. Karlstrom
Keyword(s):  
British Columbia ◽  
Geomagnetic Field ◽  
Early Pleistocene ◽  
Glacial Sediments ◽  
Banks Island ◽  
Quaternary Sequences ◽  
Matuyama Chron ◽  
Late Tertiary ◽  
Unconsolidated Sediment ◽  
Accurate Record

Mokowan Butte in southwestern Alberta is capped by 32 m of unconsolidated sediment comprising five tills and their associated paleosols. Previous stratigraphic work has indicated that the older tills are probably Early Pleistocene to late Tertiary in age. Paleomagnetic studies, based on 125 samples, show that the uppermost till–paleosol unit and the modern subsoil are normally magnetized, whereas the till–paleosol units from the middle of the sequence have reversed magnetization. We argue that these belong to the Brunhes and Matuyama polarity zones, respectively. The lowest part of the sequence has not been studied in detail and is generally too coarse for paleomagnetic sampling, and samples that have been obtained contain no accurate record of the paleofield. These new data, together with those from Wellsch Valley in Saskatchewan, Banks Island in the Northwest Territories, Fort Selkirk in the Yukon, and Merritt in British Columbia, bring to five the number of early Quaternary sequences in Canada that have yielded a record of glacial sediments deposited during the Matuyama chron, and hence record glacial events prior to the last reversal of the geomagnetic field (720 ka).

Late Cenozoic paleomagnetic record of Duck Hawk Bluffs, Banks Island, Canadian Arctic Archipelago

1990 ◽  
Vol 27 (1) ◽  
pp. 124-130 ◽  
Author(s):  
R. W. Barendregt ◽  
Jean-Serge Vincent
Keyword(s):  
Canadian Arctic ◽  
Unconsolidated Sediments ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Gradual Change ◽  
Canadian Arctic Archipelago ◽  
Late Cenozoic ◽  
Precise Position ◽  
Banks Island ◽  
Late Tertiary

Detailed paleomagnetic investigations have been completed on unconsolidated sediments from Duck Hawk Bluffs on Banks Island, in the Canadian Arctic Archipelago, that record some of the oldest late Cenozoic glacial and nonglacial events in Canada. The preglacial Worth Point Formation, the overlying Duck Hawk Bluffs Formation, including marine and glacial deposits laid down during the Banks Glaciation, and the lower part of the interglacial Morgan Bluffs Formation have magnetically reversed directions and therefore are of Matuyama age (>790 ka). Upper Morgan Bluffs Formation organic beds and deposits of the younger Thomsen Glaciation, Cape Collinson Interglaciation, and Amundsen Glaciation are normally magnetized and therefore of Brunhes age (<790 ka). The Brunhes–Matuyama boundary is recorded in the upper portion of the Morgan Bluffs Formation. Its precise position within the interglacial sequence can be identified, since the sediments document the gradual change from reversely inclined directions to normally inclined ones. These results confirm that the preglacial Worth Point Formation is at least Early Pleistocene in age and that the Banks Glaciation (the oldest and strongest continental glaciation recorded in the western Arctic) and a good part of the Morgan Bluffs Formation are of Early Pleistocene age. The study also documents a rare site in Canada where terrestrial sediments record the Brunhes–Matuyama transition and in doing so permits a precise correlation of part of the Banks Island stratigraphy with other key late Tertiary and Early to Middle Pleistocene arctic terrestrial and marine sequences.

Evidence for an Early Pleistocene glaciation in the Okanagan Valley, southern British Columbia

2014 ◽  
Vol 51 (2) ◽  
pp. 125-141 ◽  
Author(s):  
Murray A. Roed ◽  
René W. Barendregt ◽  
Jeff A. Benowitz ◽  
C.A.S. Smith ◽  
P.T. Sanborn ◽  
...  
Keyword(s):  
British Columbia ◽  
First Nation ◽  
Early Pleistocene ◽  
Pleistocene Glaciation ◽  
Pleistocene Glaciations ◽  
The West ◽  
Glacial Sediments ◽  
Fabric Analysis ◽  
Minimum Age ◽  
Okanagan Valley

Depositional evidence of Early Pleistocene glaciations in British Columbia are documented at only a few sites. Near Kelowna, in southern British Columbia, a construction project exposed glacial sediments beneath Lambly Creek Basalt, providing a minimum age for this glaciation. The basalt is composed of a number of flows yielding ages that range from 0.76 ± 0.11 to 1.5 ± 0.1 Ma. The sediments consist of a diamicton, interpreted to be till, up to 3 m thick mantled by a weakly developed paleosol. The diamicton is underlain by fluvial sands up to 5 m thick, in places revealing injection features, and minor faulting. A unit of stratified gravel underlain by grey clay is inferred to underlie the exposed sediments, based on nearby outcrops and excavations. Sediments and overlying basalts are normally magnetized and are assigned to the Jaramillo normal subchron (1.069–0.987 Ma). The till is here referred to as the Westbank First Nation Till. It is Early Pleistocene in age and represents the earliest evidence of glaciation in the Okanagan Valley. Stone fabric analysis and clast lithologies suggest that ice movement was from northwest to southeast, and is here referred to as the West Kelowna Advance; we infer that this advance was part of a larger regional glaciation. Other Early Pleistocene glaciations in the Cordillera are briefly reviewed.

The late Tertiary – Quaternary stratigraphic record of the Duck Hawk Bluffs, Banks Island, Canadian Arctic Archipelago

1983 ◽  
Vol 20 (11) ◽  
pp. 1694-1712 ◽  
Author(s):  
J.-S. Vincent ◽  
S. Occhietti ◽  
N. Rutter ◽  
G. Lortie ◽  
J.-P. Guilbault ◽  
...  
Keyword(s):  
Canadian Arctic ◽  
Canadian Arctic Archipelago ◽  
Glacial Deposits ◽  
Amundsen Sea ◽  
Glacial Sediments ◽  
Marine Deposits ◽  
Banks Island ◽  
Late Tertiary ◽  
Composite Section ◽  
Glaciomarine Sediments

The Duck Hawk Bluffs, of southwestern Banks Island in the Canadian Arctic Archipelago, record a succession of late Tertiary – Quaternary events. Organic-bearing sediments of eolian, fluvial, and lacustrine origin that overlie the Late Cretaceous Kanguk Formation and the Miocene Beaufort Formation record preglacial events of Pliocene and (or) early Quaternary age and are assigned to the Worth Point Formation. These are covered by glacial sediments of the Duck Hawk Bluffs Formation associated with the Banks Glaciation, the oldest of the three recognized glaciations to reach the island. Associated with the glacial deposits are marine or glaciomarine sediments deposited in the glacio-isostatically depressed area as the ice both advanced and retreated. These sediments are in turn covered by interglacial sediments (Morgan Bluffs Formation), by marine deposits (Big Sea sediments associated with the Thomsen Glaciation), and by younger interglacial sediments (Cape Collinson Formation). Events associated with the early Wisconsinan M'Clure Stade of the last or Amundsen Glaciation are recorded in a coastal section east of the Duck Hawk Bluffs. There, marine deposits (pre-Amundsen Sea sediments) are covered by glacial deposits (Sachs Till) of the M'Clure Stade, D/L ratios of aspartic acid in fossil wood from the Morgan Bluffs and Cape Collinson interglacial sites, respectively, vary between 0.22 and 0.31 and 0.12 and 0.13, while Holocene wood is 0.08. A composite section is proposed for these bluffs that record some of the oldest events in the Canadian Quaternary and the various units are correlated with the previously published Quaternary framework for Banks Island.

Lithostratigraphy and paleomagnetism of pre-Fraser glacial deposits in south-central British Columbia

1999 ◽  
Vol 36 (8) ◽  
pp. 1357-1370 ◽  
Author(s):  
Olav B Lian ◽  
R W Barendregt ◽  
R J Enkin
Keyword(s):  
British Columbia ◽  
Early Pleistocene ◽  
Fluvial Sediments ◽  
Optical Dating ◽  
Late Pliocene ◽  
South Central ◽  
Last Glaciation ◽  
Matuyama Chron ◽  
Sedimentary Succession ◽  
Cordilleran Ice Sheet

Lithostratigraphic records spanning considerable parts of the Pleistocene were studied at three sites in south-central British Columbia. A sedimentary succession near Pavilion includes three distinctly different till units. While the surface till can be associated with the last glaciation (the Fraser Glaciation δ18O stage 2), the ages of the two older till units are presently unknown. However, optical dating of outwash silt resting on the oldest till indicates that this outwash unit and all the overlying units are younger than ~160 ka. In Big Bar Creek valley, about 50 km north of Pavilion, an aggradational sequence of indurated glaciofluvial sand, gravel, and till is exposed. A silt unit and a sand lens within an overlying till bed near the top of the section have reversed magnetization, indicating deposition prior to 780 ka, probably during the Matuyama chron. The Big Bar Creek sequence also includes glacio(?)fluvial sediments near the base that are normally magnetized, suggesting that they were deposited, at the latest, during the Jaramillo subchron (~1.0 Ma), but probably during the Gauss chron, before 2.6 Ma. Reversely magnetized glacio(?)fluvial gravel and sand also occur along Jesmond Road between the Marble Range and Edge Hills. These units give support for the development of at least one Cordilleran ice sheet in the Early Pleistocene or Late Pliocene.

Paleomagnetic evidence for multiple Late Pliocene - Early Pleistocene glaciations in the Klondike area, Yukon Territory

2000 ◽  
Vol 37 (6) ◽  
pp. 863-877 ◽  
Author(s):  
D G Froese ◽  
R W Barendregt ◽  
R J Enkin ◽  
J Baker
Keyword(s):  
Yukon Territory ◽  
Early Pleistocene ◽  
Pleistocene Glaciations ◽  
Glacial Sediments ◽  
Late Pliocene ◽  
Matuyama Chron ◽  
Normal Polarity ◽  
Ice Wedge ◽  
Brunhes Chron ◽  
Cordilleran Ice Sheet

The Late Pliocene - Early Pleistocene terraces of the Klondike area provide a conformal record of sedimentation which marks the transition from preglacial to glacial conditions, and is one of the most complete records of glaciation and interglaciation in the northern Cordillera. Preglacial sedimentation is recorded in the Lower White Channel gravel that contains a reverse-normal polarity sequence. A re-aggradation of the nonglaciated valleys of the goldfields in response to Late Pliocene cooling is recorded by the Upper White Channel gravel, which is characterized by a dominant normal polarity with a lower reversal likely associated with the first ice-wedge casts. Klondike gravel interfingers with Upper White Channel and is normally magnetized, indicating an equivalent magnetostratigraphic unit. This glaciofluvial gravel provides evidence of extra-basinal clasts, marking a major reorganization of drainage associated with the first advance of the Cordilleran Ice Sheet in western Yukon Territory correlated with the Gauss chron (>2.58 Ma). An intermediate terrace in Klondike valley is overlain by 8 m of fluvial and glaciofluvial gravel named the Midnight Dome gravel. This gravel is mantled by 15 m of loess and hillslope deposits, named the Midnight Dome loess, which preserve at least three interglacial pollen assemblages, and a reverse-normal-reverse-normal polarity sequence assigned to the late Matuyama chron, including Jaramillo subchron (1.07-0.99 Ma), and early Brunhes chron (<0.78 Ma). The oldest glaciations here, based on the preferred interpretation, extend well into the Pliocene (>2.58 Ma) making these among the oldest glacial sediments in North America.

A new locality for primary xenolith-bearing nephelinites in northwestern British Columbia

1985 ◽  
Vol 22 (10) ◽  
pp. 1556-1559 ◽  
Author(s):  
Michael D. Higgins ◽  
John M. Allen
Keyword(s):  
British Columbia ◽  
Trace Element ◽  
Volcanic Belt ◽  
Primary Magma ◽  
Similar Composition ◽  
Element Abundances ◽  
Late Tertiary

High Ni abundances (420–500 ppm) and Mg* values (100 × Mg/(Mg + Fe2+) = 69–71) and the presence of mantle-derived xenoliths indicate that a subvolcanic nephelinite intrusion in northwestern British Columbia represents an unmodified primary magma. A separate, closely associated nephelinite intrusion shows evidence of minor olivine fractionation from a similar composition. Only three other occurrences of primary nephelinite have been described. This new occurrence suggests that these magmas may not be so rare as previously supposed. The trace-element abundances closely resemble those of primary nephelinites of similar La content from Freemans Cove, Canada. Such compositions are usually taken as evidence of intraplate rifting and doming. Therefore, these rocks are further evidence of late Tertiary or Quaternary rifting in the Stikine volcanic belt.

Permafrost, tectonics, and past and future regional climate change, Yukon and adjacent Northwest Territories

1994 ◽  
Vol 31 (1) ◽  
pp. 182-191 ◽  
Author(s):  
C. R. Burn
Keyword(s):  
Northwest Territories ◽  
General Circulation ◽  
Regional Climate ◽  
Gulf Of Alaska ◽  
General Circulation Models ◽  
Yukon Territory ◽  
Early Pleistocene ◽  
Tectonic Activity ◽  
Near Surface ◽  
Late Tertiary

Late Tertiary changes in the general circulation of the atmosphere, regionally enhanced by uplift of the Wrangell – Saint: Elias and Coast mountains, were sufficient to promote permafrost development in the western Arctic. Permafrost developed in Yukon Territory and adjacent Northwest Territories during early Pleistocene glacial periods, after continued tectonic activity led to further modification of regional climate, but degraded in the interglacials. Permafrost has been present in northern parts of the region since the Illinoian glaciation, but most ground ice in central Yukon formed in the Late Wisconsinan. The present interglacial is the only one with widespread evidence of permafrost, which is maintained in the valleys of central and southern Yukon by the Saint Elias Mountains blocking continental penetration of maritime air from the Gulf of Alaska. This reduces snow depth in winter, while cold-air drainage in the dissected terrain of the Yukon Plateaus enhances the near-surface inversion, leading to continental minimum temperatures. General circulation models used to simulate climate represent the physiography of northwest Canada crudely. As a result, the simulations are unable to reproduce conditions responsible for the development and preservation of permafrost in the region.

Model of evolution of the Bella Coola – Ocean Falls Region, Coast Mountains, British Columbia

1968 ◽  
Vol 5 (6) ◽  
pp. 1429-1441 ◽  
Author(s):  
A. J. Baer
Keyword(s):  
British Columbia ◽  
Granitic Rocks ◽  
Coast Mountains ◽  
Early Tertiary ◽  
Upper Paleozoic ◽  
Late Tertiary ◽  
Bella Coola

Granitic rocks and metavolcanics underlie most of the Coast Mountains of British Columbia between the fifty-second and the fifty-third parallel, about half-way between Vancouver and Prince Rupert. The age of most rocks is unknown. The area has been involved in at least two orogenic cycles. The oldest known supracrustal rocks (Upper Paleozoic?) have been metamorphosed to gneisses, deformed along northeasterly trends, and intruded by granitic plutons, probably early in the Mesozoic Era. These rocks formed the basement of disconformable Mesozoic sediments and volcanics. The basement and its Mesozoic cover were metamorphosed and deformed along northwesterly trends in the early Tertiary. In the late Tertiary (Pliocene?) post-kinematic granites were emplaced and basalts were extruded for a period extending to postglacial times. The model is possibly applicable to all of the Coast Mountains in Canada.

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