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TitleInsights into the Connaught sequence of the Timiskaming varve series from Frederick House Lake, northeastern Ontario
AuthorBrooks, G RORCID logo
SourceCanadian Journal of Earth Sciences 2021 p. 1-15,
Alt SeriesNatural Resources Canada, Contribution Series 20200566
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
RelatedThis publication is related to Thickness record of varves from glacial Ojibway Lake recovered in sediment cores from Frederick House Lake, northeastern Ontario
File formatpdf; html
NTS42A/10; 42A/11; 42A/14; 42A/15
AreaFrederick House Lake
Lat/Long WENS -81.1667 -80.5000 49.0000 48.5000
Subjectssurficial geology/geomorphology; stratigraphy; geophysics; Science and Technology; Nature and Environment; lake sediments; varves; clastics; lake sediment thickness; landslide deposits; geophysical surveys; acoustic surveys; systematic stratigraphy; disconformities; glacial history; glaciation; depositional history; lake sediment cores; Connaught Sequence; Timiskaming Series; Glacial Lake Ojibway; Matagami Series; Laurentide Ice Sheet; Cochrane Advance; lacustrine sediments; colluvial and mass-wasting deposits; glaciolacustrine sediments; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; geophysical profiles; tables; lithologic logs; geophysical images; time series
ProgramPublic Safety Geoscience Plate Boundary Earthquakes
Released2021 05 13
AbstractA 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, Canada. 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 underlie and overlie the MTD. Comparison to regional published varve series reveals two possible interpretations for the varve numbering: varve (v) 2066 to v2115, which requires the inference of a 55 varve year (vyr) disconformity just below the Connaught sequence, while the alternative numbering, v2011a to v2060a (a = alternative), extends continuously from older varves. Circumstantial evidence supporting the alternative numbering is as follows: (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 about 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 v2074a rather than v2129 in the original numbering.
Summary(Plain Language Summary, not published)
Clastic varves are sediments that accumulate in glacial lakes. Similar to tree rings, they can be used to date deposits or features in glacial lakes. This paper is identifies and corrects a discrepancy to the numbering of the youngest varves in Timiskaming varves series. These varve accumulated in glacial Lake Ojibway, northeastern Ontario-western Quebec, as the Laurentide Ice Sheet was receding in the region.

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