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TitleEarly Paleozoic seas of offshore eastern Canada: insights from the lithology and palynology of lower Paleozoic strata from the Labrador Margin
AuthorBingham-Koslowski, NORCID logo
SourceGAC®-MAC 2021, London, Canada: Exploring Geosciences Through Time and Space/GAC®-MAC 2021, London, Canada : Explorer les géosciences à travers le temps et l'espace; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 44, 2021 p. 40 Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210167
PublisherGeological Association of Canada
MeetingGAC-MAC 2021: Geological Association of Canada-Mineralogical Association of Canada Joint Annual Meeting 2021; London, ON; CA; November 1-5, 2021
Mediadigital; on-line
File formatpdf
ProvinceNewfoundland and Labrador; Northern offshore region
NTS14; 15
Lat/Long WENS -61.0000 -56.0000 65.0000 52.0000
Subjectsmarine geology; regional geology; stratigraphy; paleontology; Science and Technology; Nature and Environment; continental margins; paleoenvironment; bedrock geology; lithology; sedimentary rocks; carbonates; dolostones; limestones; sandstones; siltstones; mudstones; palynology; diagenesis; alteration; dolomitization; biostratigraphy; exploration wells; core samples; sedimentary structures; bioturbation; fossil assemblages; systematic stratigraphy; correlations; Labrador Margin; Hopedale E-33 Well; South Hopedale L-39 Well; Tyrk P-100 Well; Gudrid H-55 Well; Roberval K-92 Well; Indian Harbour M-52 Well; Freydis B-87 Well; Phanerozoic; Paleozoic; Carboniferous; Ordovician
ProgramGEM2: Geo-mapping for Energy and Minerals Baffin Region
Released2021 11 01
AbstractThe lower Paleozoic stratigraphy of the Labrador margin is poorly understood due to the scarcity of samples from the offshore, the occurrence of diagenetic alteration (dolomitization), and a lack of up-to-date biostratigraphic data. Paleozoic rocks, known from seven wells on the Labrador margin, represent erosional remnants primarily associated with Cretaceous syn-rift half grabens: the wells are Hopedale E-33, South Hopedale L-39, Tyrk P-100, Gudrid H-55, Roberval K-92, Indian Harbour M-52, and Freydis B-87. Due to limited data, it was previously unknown whether the Paleozoic strata in these seven wells could be correlated with one another, or how they relate to other Paleozoic occurrences in Davis Strait and on Baffin Island. Of the seven wells, only four contain conventional cores in the Paleozoic interval: Gudrid H-55, Roberval K-92 (cores #6 and #7), Indian Harbour M-52, and Freydis B-87 (cores #1 and #2). Of these six cores, lithological analysis shows that five are composed of carbonate rocks, with dolostones present in Gudrid H-55 and Roberval K-92 and fossiliferous limestones occur in Indian Harbour M-52 and Freydis B-87 (core #2). The sixth core, Freydis B-87 (core #1), consists of siliciclastic lithologies, including massive and laminated sandstones, siltstones, and mudstones with varying degrees of bioturbation. Similar lower Paleozoic fossil assemblages are observed in Indian Harbour M-52 and Freydis B-87 (core #2), but the pervasive dolomitization of the Gudrid H-55 and Roberval K-92 cores prevents meaningful correlations among the four wells. Previous palynological studies on the Labrador margin Paleozoic strata provide no further clarification as they report a range of ages for the seven wells, including Ordovician, Devonian, Carboniferous, and undifferentiated Paleozoic. Thus, a new palynological study was conducted on all seven wells and recorded, for the first time, consistent Ordovician ages spanning an interval from possible Middle Ordovician (Tyrk P-100, Roberval K-92, and Indian Harbour M-52) to Katian (Indian Harbour M-52). This study resulted in the Paleozoic strata in Gudrid H-55 and Roberval K-92 being reassigned to the Ordovician from the Carboniferous; to new age determinations for the Paleozoic rocks of South Hopedale L-39 and Tyrk P-100 (formerly undifferentiated Paleozoic); and to the refinement of the Paleozoic ages to stage level in Hopedale E-33, Indian Harbour M-52, and Freydis B-87. The findings of this study imply that the Paleozoic of the Labrador margin is syndepositional and therefore correlatable, and is similar in age to other lower Paleozoic strata from Canada's northern Atlantic margin.
Summary(Plain Language Summary, not published)
The lower Paleozoic strata that occurs in seven wells offshore Labrador, is poorly understood due to a lack of samples and data. This study analyzed the available Paleozoic cores and palynological slides to determine the relationship of the Labrador margin Paleozoic occurrences to one another, as well as to other Paleozoic strata located to the north in Davis Strait and onshore Baffin Island. The lithological analysis was done on six conventional cores from four wells that penetrat Paleozoic strata. Five of these cores were composed of carbonate rocks (dolostones and limestones) while the sixth was composed of siliciclastic rocks (sandstones, siltstones, and mudstones). Two of the cores share a similar fossil assemblage, characteristic of the lower Paleozoic, however, due to the pervasive dolomitization of half the cores, it was not possible to determine if the four wells were correlatable. The study then turned to palynology but previous palynological studies on the seven Paleozoic wells were outdated and contained conflicting age assignments. As such, a new palynological study was undertaken and demonstrated, for the first time, a consistent age of Ordovician for each of the seven wells. Based on the results of this palynology study, two of the wells were reassigned from the Carboniferous to Ordovician, two were given new age determinations (previously undifferentiated Paleozoic), and the remaining three had their ages refined to the stage level. The palynology, combined with the lithological analysis, shows that the Paleozoic on the Labrador margin is all related and of similar age to other lower Paleozoic strata from the northern Atlantic margin.

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