The last 100 million years on the Scotian Margin, offshore eastern Canada: an event-stratigraphic scheme emphasizing biostratigraphic data

In order to provide a detailed stratigraphic framework for the Late Cretaceous and Cenozoic basin fill of the Scotian Margin (the continental shelf and continental slope off Nova Scotia, eastern Canada), we have developed an event-biostratigraphic scheme based mainly on new analyses of several exploration wells. These include the following shelf wells — Demascota G-32, Hesper I-52, Onondaga E-84 and Wenonah J-75 — as well as Shelburne G-29 and Shubenacadie H-100 on the slope. Several fossil groups are involved in this study, most notably dinoflagellate cysts (dinocysts) and nannofossils, with the former generally providing more diverse assemblages and the latter more precise calibration with global correlations. Because most of the material studied is from cuttings samples, we have relied largely on Last Appearance datums (LADs). The scheme incorporates information from about 250 microfossil species (or groups of species), delimiting about 180 events. Not all events occur in all wells and the scheme needs to be tested against future observations: nevertheless, it represents a considerable advance on previous schemes, which were based mostly on broad zones rather than detailed events. Moreover, it allows for a more refined assessment of ages of geological events, such as the early Eocene gamma spike and the incision of the Wenonah Canyon. And it provides an accurate age context for ongoing stratigraphic, sedimentological and paleoenvironmental studies, and ultimately for a fuller understanding of petroleum systems on the Scotian Margin. RÉSUMÉ Pour fournir un cadre stratigraphique détaillé du remplissage du Crétacé tardif et du Cénozoïque du bassin de la marge Néo-Écossaise (plateau continental et pente continentale au large de la Nouvelle-Écosse, est du Canada), nous avons mis au point une formule événementielle-biostratigraphique principalement basée sur de nouvelles analyses de plusieurs puits d’exploration. Ces derniers comprennent les puits Demascota G-32, Hesper I-52, Onondaga E-84 et Wenonah J-75 sur le plateau continental ainsi que Shelburne G-29 et Shubenacadie H-100 sur la pente continentale. L’étude touche plusieurs groupes de microfossiles, plus particulièrement les kystes de dinoflagellés (dinokystes) et les nannofossiles, les premiers procurant généralement des assemblages plus diversifiés et les derniers, un étalonnage plus précis avec des corrélations mondiales. Comme la majeure partie du matériel étudié provient d’échantillons de déblais, n