Evidence for Early Pleistocene glaciation from borecore stratigraphy in north-central Alberta
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Date
2016-07
Authors
Andriashek, L. D.
Barendregt, René W.
Journal Title
Journal ISSN
Volume Title
Publisher
Alberta Energy Regulator
Abstract
Borecores collected from Quaternary sediments in north-central Alberta, Canada, were sampled and
studied for paleomagnetic remanence characteristics. A magnetostratigraphy has been established
for sediments previously assumed to represent multiple continental (Laurentide) glaciations but for
which no geochronology was available. Based on the Quaternary record elsewhere in Alberta and
Saskatchewan,
it was thought that some of these sediments were deposited during pre-late Wisconsinan glaciations.
The Quaternary sedimentary succession of north-central Alberta attains thicknesses up to 300 m
within buried valleys and is composed of diamict interbedded with glaciolacustrine and outwash
sediments. Most of the sampled units are not accessible from outcrop and their sedimentology and
stratigraphy is derived from core data only. In 4 of 16 borecores sampled to date, diamict that
correlates with the Bronson Lake Formation till is reversely magnetized, indicating an Early
Pleistocene age. Depending on location, this formation is underlain by either Empress Formation
sediments or Colorado Group shales, and is overlain by one or more normally magnetized glacigenic
sedimentary units of the Bonnyville, Marie Creek, and Grand Centre formations, respectively. This
new record of Early Pleistocene glaciation in north-central Alberta places the westernmost extent
of earliest Laurentide ice at least 300 km farther west than its previously established limit in
the Saskatoon and Regina regions of the Canadian Interior Plains, but still to the east of the
maximum extent of the late Wisconsinan (Late Pleistocene) Laurentide Ice Sheet, which extended into
the foothills of the Alberta and Montana Rocky Mountains.
Description
Open access
Keywords
Borecore stratigraphy , Early Pleistocene glaciations , Laurentide glaciations , Quaternary sediments , Glacial deposits , Paleomagnetic sampling , Magnetostratigraphic interpretation , North-central Alberta
Citation
Andriashek, L. D., & Barendregt, R. W. (2016). Evidence for Early Pleistocene glaciation from borecore stratigraphy in north-central Alberta. (AER/AGS Report 92). Alberta Energy Regulator. https://static.ags.aer.ca/files/document/REP/REP_92.pdf