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

Abstract

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 eventbiostratigraphic scheme based mainly on new analyses of several exploration wells. They include Demascota G-32, Hesper I-52, Onondaga E-84 and Wenonah J-75 on the continental shelf, as well as Shelburne G-29 and Shubenacadie H-100 on the continental slope. Several microfossil 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, of which about 50 percent are based on nannofossils, some 46 percent on palynomorphs and 4 percent on foraminifera. 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 late Paleocene 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. RÉSUMÉPour 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, nous nous sommes largement appuyés sur les plans de référence des dernières manifestations. La formule incorpore des données provenant d'environ 250 espèces (ou groupes d'espèces) de microfossiles délimitant quelque 180 phénomènes, dont environ 50 % sont basés sur des nanofossiles, quelque 46 % sur des palynomorphes et 4 % sur des foraminifères. Les phénomènes en question ne se manifestent pas tous dans tous les puits et il faut...

Geophysical evidence for widespread Cenozoic bottom current activity from the continental margin of Nova Scotia, Canada

“…2) (Wade and MacLean, 1990;Fensome et al, 2008). Due to a paucity of data, formations along the deep water Scotian margin are not formalized and no detailed lithostratigraphic summary exists.…”

Batiacasphaera bergenensis and Lavradosphaera elongata — New dinoflagellate cyst and acritarch species from the Miocene of the Iceland Sea (ODP Hole 907A)

“…4), both species might be of some importance to constrain the Middle to Late Miocene boundary in deposits off East Greenland, and may help to further refine the biostratigraphic framework in order to address the evolution of the Greenland ice sheet in more detail. Fensome et al, 2008;Schreck et al, 2012), and Batiacasphaera bergenensis sp. nov. and Lavradosphaera elongata sp.…”

A response to ‘Comment to Wetzeliella and its allies – the ‘hole’ story: a taxonomic revision of the Paleogene dinoflagellate subfamily Wetzelielloideae by Williams et al. (2015)’

“…One of us spent several years analyzing Late Cretaceous and Cenozoic assemblages from the Scotian Basin, offshore eastern Canada (Fensome et al 2008(Fensome et al , 2009. Wetzelielloids are relatively common in many assemblages from Paleogene strata in the Scotian Basin, but it was puzzling that specimens with a clearly "popped-out" epeliform archaeopyle like those in Williams and Downie's (1966) classic wetzelielloid study were rarely if ever observed; all Scotian Basin wetzelielloids showed a soleiform archaeopyle or no clearly evident archaeopyle.…”