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TitleQuaternary stratigraphy and glacial history at Peace River, Alberta: implications for mapping and modeling of older continental ice sheet limits in western Canada
AuthorPaulen, R CORCID logo; Beaudoin, A BORCID logo; Ross, MORCID logo
SourceXXI INQUA Congress - Program with Abstracts; by INQUA; 2023 p. 1
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20220377
MeetingXXI INQUA Congress; Rome; IT; July 14-20, 2023
Mediapaper; digital; on-line
File formatpdf
AreaPeace River
SubjectsScience and Technology; general geology; glaciology; Stratigraphy; Quaternary
ProgramGEM-GeoNorth: Geo-mapping for Energy and Minerals GEM Program Coordination
Released2023 07 14
AbstractThe number and style of the continental Laurentide Ice Sheet (LIS) glacial advances in the western prairies of North America has been the subject of debate, especially in the Peace River district of western Alberta and eastern British Columbia. Given its northern Alberta location, resolving the glacial record of this area has important implications for understanding the evolution of the LIS, especially during its earlier (pre-Late Wisconsin) phases. The Quaternary stratigraphy documented in Alberta’s Peace River lowlands has been subject to conflicting interpretations. This is probably due to the absence of a single complete stratigraphic sequence preserved at any one section (reflecting extensive landsliding along the Peace River valley), and a lack of chronologic control for lower parts of the sequence.

The valley-fill sediments located at the confluence of the Heart and Peace rivers, within the town of Peace River, Alberta, provide perhaps the best record in the Interior Plains of western Canada of an almost continuous sequence of Quaternary sedimentation extending from the bedrock surface to present. Here, a 187 m thick composite stratigraphy records the transition from preglacial fluvial sedimentation (Unit 1), to a penultimate proglacial sedimentary sequence (Units 2 and 3) that is conformably overlain by interstadial fluvial sediments (Unit 4) of possible MIS-3 age, or older (based on limiting radiocarbon dates). In turn, these sediments are overlain by a Late Wisconsin ice advance/retreat cycle of sedimentation from the LIS (Units 5-8). The sequence is capped with Holocene loess with paleosols, containing mollusc and plant macrofossils. The only till unit in the stratigraphy (Unit 7) is from the Late Wisconsin glacial advance. Clasts of Canadian Shield lithologies in the lower fluvial sediments (Unit 2) are derived from southwestward draining southern Buffalo Head Hills catchments, where multiple, older glacial sediments have been documented. Consequently, we argue that there is evidence for only a single continental (Laurentide) glaciation in the eastern Peace River district, similar to what is defined to the southwest in Quaternary exposures along the Smoky River.
Summary(Plain Language Summary, not published)
Summary of the glacial event stratigraphy for the northwestern sector of the Laurentide Ice Sheet, in one of the largest preglacial valleys in northwest Canada. The sedimentary units exposed there have rarely been documented in their entirety. This is important for constraining older ice sheet models, which are often constructed for the entire northern hemisphere.

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