| Titre | An integrated paleoenvironmental study of Lower Cretaceous to lower Cenozoic strata of the Labrador margin, offshore eastern Canada |
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| Auteur | Dafoe, L T ;
Williams, G L |
| Source | The Atlantic Geoscience Society (AGS), 47th Colloquium and Annual Meeting, program with abstracts/La Société Géoscientifique de l'Atlantique, 47th Colloquium and Annual Meeting, program with abstracts;
2021 p. 17-18  Accès ouvert |
| Liens | Online - En ligne (complete volume - volume complet, PDF, 1.12 MB)
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| Année | 2021 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200739 |
| Éditeur | Société géoscientifique de l'Atlantique |
| Réunion | The Atlantic Geoscience Society-La Société Géoscientifique de l'Atlantique 47th Colloquium and Annual Meeting; février 5-6, 2021 |
| Document | livre |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Terre-Neuve-et-Labrador; Région extracotière de l'est |
| Région | Labrador; Mer du Labrador |
| Sujets | Paléogène; Paléocène; Eocene; Crétacé inférieur; marges continentales; paléoenvironnement; bassins sédimentaires; antécédents tectoniques; décrochement horizontal; échantillons carrotés; fossiles;
empreintes fossiles; ichnologie; ichnofaciès; macrofossiles; palynologie; palynomorphes; miospores; microfossiles; assemblages fossiles; structures sédimentaires; milieu sédimentaire; salinité; Plaque de l'Amérique du Nord; Plaque de Groenland;
Bassin d'Hopedale ; Bassin de Saglek ; Dinoflagellés; Méthodologie; tectonique; sédimentologie; paléontologie; Nature et environnement; Sciences et technologie; Phanérozoïque; Cénozoïque; Tertiaire; Mésozoïque; Crétacé |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Région de Baffin |
| Diffusé | 2021 02 01 |
| Résumé | (disponible en anglais seulement)
Rifting and opening of the Labrador Sea began in the Early Cretaceous and ceased in the latest Eocene as the Greenland plate separated from the paleo-North
American plate. A record of this tectonism is preserved in the stratigraphic successions of the Hopedale and Saglek basins, respectively to the south and north along the Labrador margin. Previous paleoenvironmental studies of these strata have
primarily focused on a single methodology using cuttings samples, typically microfossils or sedimentological observations, to define paleoenvironments. In this study, we use conventional core intervals to combine macroscopic observations of the
sedimentology and ichnology with quantitative microscopic palynological analyses of bisaccates, other miospores, dinoflagellate cysts (dinocysts), acritarchs, and other palynomorphs to provide robust paleoenvironmental interpretations. The results
are reported for 23 core intervals from 14 wells representing key intervals from the Early Cretaceous to basal Ypresian, with palynological counts from a total of 64 samples. The sedimentological and ichnological observations generally provide well
defined interpretations of the paleoenvironment, while the palynomorph ratios indicate an approximate distance from the shoreline. Lower Cretaceous mudstones are typically devoid of dinocysts and acritarchs but contain bisaccates and other miospores:
the palynological assemblages combined with low diversity and low abundance trace fossil suites indicate a restricted (brackish) marine embayment. Upper Cretaceous mudstones deposited in slope-equivalent and shelfal-equivalent water depths show high
proportions of dinocysts and acritarchs relative to miospores, as expected. The slope strata are devoid of trace fossil suggesting reduced oxygenation, but fully marine Cruziana Ichnofacies characterize bioturbated shelfal strata. The Upper
Cretaceous, and Selandian-basal Ypresian deposits are mostly deltaic, reflecting various depositional conditions. Storm- or wave-influenced deposits are characterized by low dinocyst and acritarch abundances and weakly stressed expressions of the
Cruziana Ichnofacies. River-influenced deltaic strata mostly contain limited dinocyst and acritarch abundances with sedimentary structures prevalent and highly stressed expressions of the Cruziana Ichnofacies are present. River-dominated and
tide-dominated (channel) strata lack marine palynomorph indicators, with sedimentary structures predominating. Dinocyst and acritarch results tend to parallel trace fossil diversity and abundance, but can be misleading in highly brackish settings
where these marine indicators may not be present. Palynomorph counts can, however, help to refine paleoenvironments from strata that contain non-ubiquitous sedimentary features and can provide evidence of mixing of shallow and deeper water settings,
such as progradation of a delta into deeper water. Overall, integration of the two methodologies, operating at very different scales, provides more robust paleoenvironmental interpretations. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les événements géologiques liés à la formation de la mer du Labrador sont enregistrés dans les couches stratigraphiques trouvées dans les
bassins sédimentaires le long de la marge du Labrador. Les matériaux de carotte provenant des bassins sont évalués pour les paléoenvironnements en combinant différentes méthodologies pour une interprétation plus robuste. |
| GEOSCAN ID | 328087 |
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