Barendregt, Rene

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Now showing 1 - 5 of 21
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    Characterization of Lower and Middle Pleistocene tephra beds in the southern plains of western Canada
    (Canadian Science Publishing, 2022) Westgate, John A.; Naeser, Nancy D.; Barendregt, René W.; Pearce, Nicholas J. G.
    Wellsch Valley tephra, near Swift Current, southwestern Saskatchewan, and Galt Island tephra, near Medicine Hat, southeastern Alberta, have been referenced in the literature since the 1970s, but little is available on their physical and chemical attributes — necessary information if they are to be recognized elsewhere. This study seeks to remedy this situation. Both have a calc-alkaline rhyolitic composition with hornblende, biotite, plagioclase, pyroxene, and Fe–Ti oxides being dominant. They have a similar composition but are not the same. Wellsch Valley tephra has a glass fission-track age of 0.75 ± 0.05 Ma, a reversed magnetic polarity, and was deposited at the close of the Matuyama Chron. Galt Island tephra has an age of 0.49 ± 0.05 Ma, a normal magnetic polarity, and was deposited during the early Brunhes Chron. Rich fossil vertebrate faunas occur in sediments close to them. Major- and trace-element concentrations in their glass shards indicate a source in the Cascade Range of the Pacific Northwest, USA, but differences in trace-element ratios suggest they are not consanguineous.
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    Magnetostratigraphy of quaternary sections in eastern Alberta, Saskatchewan and Manitoba
    (Elsevier, 2011) Barendregt, René W.
    This paper summarises the continental (Laurentide) glacial history of the northern Interior Plains of Canada (Alberta, Saskatchewan, and Manitoba) using magnetostratigraphy, tephrochronology, and paleosol data collected at type sections. The use of borecores for retrieval of oriented till samples for paleomagnetic analysis, is discussed.
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    Stratigraphical record of glacials/interglacials in northwest Canada
    (Elsevier, 2011) Barendregt, René W.; Duk-Rodkin, Alejandra
    This chapter deals with stratigraphical correlations of glacial and interglacial deposits found in the northern Canadian Cordillera and in the northern Interior Plains of Canada. The sequences described here record multiple glacial events commencing at 2.7 Ma in the mountains and 1.6 Ma in the low latitude Arctic Islands. Extent and timing of these glaciations are based on magnetostratigraphy, tephrochronology, radiometric dating, paleosols and pollen.
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    Chronology and extent of late Cenozoic ice sheets in North America: a magnetostratigraphical assessment
    (Elsevier, 2011) Barendregt, René W.; Duk-Rodkin, Alejandra
    This paper summarises the advances which have been made in the magnetostratigraphic assessment of glacial and interglacial events of the past 3.0 million years, to facilitate the assignment of sediments to the Chrons and subchrons of the geomagnetic polarity timescale. In the absence of absolute dating tools, magnetostratigraphy affords a valuable means of assigning terrestrial ice age deposits to the geologic timescale, and most importantly, allows a correlation to be made with the more complete marine sedimentary record, where oxygen isotopic data also provide a robust paleotemperature record.
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    Late Cenozoic geology, Ancient Pacific Margin Natmap Project, report 4: paleomagnetic and geomorphic evidence for Brunhes-age volcanism, Fort Selkirk and Rosebud Creek area, Yukon Territory
    (Geological Survey of Canada, 2001) Huscroft, Crystal A.; Barendregt, René W.; Jackson, Lionel E.
    Normally magnetized, valley-filling basalt flows extend more than 10 km down the Yukon River valley from the Fort Selkirk area. These flows are locally overlain by gravel and terminate at the level of the contemporary Yukon River flood plain, suggesting a middle to late Pleistocene age for this previously unrecognized eruptive event. Unlike other valley-filling phases of the Selkirk Volcanic Group, this eruption postdates the Pliocene to early Pleistocene pre-Reid glaciations. Normal magnetism was also determined for basalt flows underlying terraces in the area of the Rosebud Creek-Grand Valley Creek confluence, 60 km to the northwest of the Fort Selkirk area. Based on their unique geomorphic and stratigraphic settings, the Rosebud basalt flows may represent yet another period of Pleistocene volcanism which predates one of the pre-Reid glaciations in the central Yukon Territory.