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TitleRefining 2 km of Ordovician chronostratigraphy beneath Anticosti Island utilizing integrated chemostratigraphy
AuthorMcLaughlin, P I; Emsbo, P; Desrochers, A; Bancroft, A; Brett, C E; Premo, W; Neymark, L; Riva, J F; Achab, A; Asselin, E; Emmons, M
SourceCanadian Journal of Earth Sciences vol. 53, 2016 p. 865-874,
Alt SeriesEarth Sciences Sector, Contribution Series 20150431
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
AreaAnticosti Island
Lat/Long WENS -63.5000 -63.0000 49.7500 49.0000
Subjectsgeochronology; paleontology; stratigraphy; chronostratigraphy; systematic stratigraphy; biostratigraphy; drill core analyses; core analysis; unconformities; sedimentation rates; shales; lithostratigraphy; Ordovician
Illustrationslocation maps; stratigraphic cross-sections; geochemical plots
ProgramGeoscience for New Energy Supply (GNES) Program Coordination
Released2016 05 06
AbstractNew high-resolution chemostratigraphy, in combination with updated biostratigraphy, refines and increases the chronostratigraphic resolution of the nearly 2 km-thick Ordovician section below Anticosti Island. A total of 1414 horizons, spaced at 1.0 to 1.5 m intervals, were sampled from the New Associated Consolidated Paper (NACP) drill core and analyzed for their elemental composition by pXRF. Select powders were then analyzed for d13Ccarb (N=364) and 87Sr/86Sr (N=25). The combination of 87Sr/86Sr and d13Ccarb stratigraphy was particularly effective in assessing the age of the lower succession that lacks biostratigraphy in the core. Our results indicate a Floian to early Darriwilian (Flto Dw1) age for the Romaine Formation, a middle Darriwilian (Dw2) age for the Mingan Formation, a lower to mid-Katian (Ka1-Ka2) age for the Macasty Formation, an upper Katian (Ka3) age for the base of the Vauréal Formation, an uppermost Katian (Ka4) age for the remaining Vauréal and a Hirnantian (H1) age for the Ellis Bay Formation. This integrated chemostratigraphic and biostratigraphic synthesis allows for estimates on the duration of depositional sequences, their bounding unconformities, and sedimentation rates.
Summary(Plain Language Summary, not published)
Analyses of high resolution chemostratigraphy were conducted across the Ordovician subsurface succession of the the NACP well of the Anticosti basin, which is about 2 km thick. The profiles of the carbon C13 and 87Sr/ 86Sr ratios, as well as those acquired by X-ray fluorescence spectrometry(pXRF)on the major chemical components of rocks, combined with the updating of biostratigraphic data (fossils), allowed to refine the chronostratigraphic resolution of the succession by documenting the chronology of events such as the duration of depositional sequences, their bounding unconformities sedimentation rates.

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