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TitleRevised biostratigraphic and thermal alteration interpretations for the Paleozoic of the Hopedale Basin, offshore Labrador, Canada
AuthorBingham-Koslowski, NORCID logo; Miller, M A; McCartney, TORCID logo; Carey, J SORCID logo
SourceBulletin of Canadian Petroleum Geology vol. 67, no. 3, 2019 p. 185-213
Alt SeriesNatural Resources Canada, Contribution Series 20180433
PublisherCanadian Society of Petroleum Geology
Mediapaper; on-line; digital
File formatpdf; html
ProvinceNewfoundland and Labrador; Eastern offshore region
NTS3; 13; 14
AreaLabrador Sea
Lat/Long WENS -60.0000 -52.0000 57.0000 53.0000
Subjectspaleontology; stratigraphy; fossil fuels; Nature and Environment; Science and Technology; biostratigraphy; thermal alteration; sedimentary basins; exploration wells; palynology; palynomorphs; miospores; fossil assemblages; thermal maturation; continental margins; paleoenvironment; sample preparation; petroleum exploration; hydrocarbon potential; Hopedale Basin; 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; Acritarchs; Chitinozoans; Leiospheres; Desmochitina; Methodology; Phanerozoic; Paleozoic; Ordovician
Illustrationslocation maps; geoscientific sketch maps; tables; photomicrographs; geophysical logs
ProgramGEM2: Geo-mapping for Energy and Minerals Baffin Region Atlas
Released2019 09 01
AbstractPaleozoic rocks occur in seven wells in the Hopedale Basin, offshore Labrador (Hopedale E-33, South Hopedale L-39, Tyrk P-100, Gudrid H-55, Roberval K-92, Indian Harbour M-52, and Freydis B-87), where they represent erosional remnants primarily associated with Cretaceous syn-rift half grabens. Previous palynological studies have reported a range of ages for the Paleozoic in these wells, including Ordovician, Devonian, Carboniferous, and undifferentiated Paleozoic. Palynological analyses in the present study confirm that recovery is limited, primarily due to the predominance of lithologies that hinder palynomorph preservation, specifically dolostones. Palynomorphs (predominantly acritarchs and chitinozoans) have been analyzed from new and archived samples from the seven wells and have, for the first time, produced consistent age determinations for the Paleozoic strata in all wells: palynomorph assemblages considered in place indicate a Middle to Late Ordovician age. Thermal maturity was determined from Ordovician acritarchs and leiospheres observed in the Gudrid H-55, Roberval K-92, Indian Harbour M-52, and Freydis B-87 wells, with thermal alteration indices (TAI) ranging from approximately 5+ to 6+ (dry gas). Carboniferous miospores are present from Paleozoic strata in the southern Hopedale Basin wells, where their TAI values range from 3+ to 4. These miospores are interpreted as contaminants introduced into the samples via cavings or as drilling mud contamination. The data presented here provides new biostratigraphic constraints for the Paleozoic of the Hopedale Basin (Middle to Late Ordovician), facilitates the correlation of the Paleozoic intervals in these wells, and enables the consideration of Labrador margin Lower Paleozoic strata in regional studies as well as in paleogeographic and paleoenvironmental reconstructions.
Summary(Plain Language Summary, not published)
Seven wells located in the Hopedale Basin, offshore Labrador, intersect Paleozoic rocks. Previous age-dating studies on the Paleozoic interval have resulted in conflicting and inconsistent dates for the rocks ranging from undifferentiated Paleozoic, to Ordovician, to Devonian, to Carboniferous. Without consistent age data, the rocks in these wells cannot be correlated to each other, let alone, used for regional or global scale correlations. This study presents new age data for the Paleozoic of the Hopedale Basin, demonstrating for the first time that the rocks are all Ordovician. 168 samples were analyzed and palynomorphs of acritarchs, chitinozoans, scolecodonts, and graptolites were used to establish age constraints. Thermal alteration indices are also presented providing information regarding the thermal maturity of the Paleozoic rocks. This study and the age data it presents, now enables the inclusion of the Labrador margin Paleozoic rocks in global paleoenvironmental studies.

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