ALBERT

Description: The detrital mineralogy of Upper Jurassic to Lower Cretaceous sandstones from the Continental Offshore Stratigraphic Test G-2 well in the Georges Bank Basin was studied to better understand the varying supply of clastic sediment to the basin. Heavy minerals separated from cuttings were identified by chemical analyses, zircons were dated, and Raman spectroscopy was applied to identify titania polymorphs (rutile, anatase, and brookite). Upper Jurassic (Oxfordian) sands contain tourmaline, fluorapatite, Mn-almandine and grossular garnets (derived from the central Maine and coastal Maine belts), and pumice and trachytes reworked from volcanics in the Long Island platform. Zircon geochronology (300–450 and 550–700 Ma) supports sources from peri-Gondwanan Appalachian terranes. Lower Cretaceous heavy minerals show that Oxfordian supply was diluted to 30%, mostly by additional ilmenite, zircon, tourmaline, and staurolite, probably by components from central and northern Maine and New Brunswick. Rutile and anatase from metapelites are more common than in the Oxfordian, where mafic igneous sources predominate. Lower Cretaceous zircons include a few Mesoproterozoic grains that might be reworked from middle Paleozoic sedimentary rocks in the Gander terrane of northern Maine and New Brunswick, although subhedral grains together with rare chromite may indicate minor or intermittent supply from the Sable River draining Labrador. Heavy minerals provided important provenance information not available from zircon geochronology alone. Progressive enlargement of the catchment area resulted from an increasingly humid climate in the latest Jurassic and active mostly northeast-trending faults in the Early Cretaceous. This resulted in greater supply of petrographically more-mature sand to the basin.

Description: The Jeanne d'Arc Basin is a relatively small passive-margin rift basin that underlies what is now the northeastern corner of the Grand Banks of Newfoundland. In the Late Cretaceous and early Paleogene, the basin formed an elongated depression where sediment accumulated in and along the margins of a shallow-shelf sea. Seismic and well data were used to examine the Late Cretaceous and Paleogene evolution of the basin and to formally revise the existing stratigraphic classification scheme. In the Late Cretaceous, the western margin of the basin was characterized by a well-developed shelf and slope system comprised of the sand-prone Otter Bay and Fox Harbour members and the distally equivalent shale-prone Red Island and Bay Bulls members, respectively. These members record two main progradational episodes that are separated by a regional unconformity and a thick shale interval corresponding to the Bay Bulls Member. East of the shelf-slope system, Upper Cretaceous shale and sparse sandstone of the Dawson Canyon Formation and chalk of the Petrel Member and Wyandot Formation were deposited in a relatively condensed section. In the early part of the Paleogene, two main sandstone units, herein named the Avondale and South Mara members, were deposited east of the well-developed latest Cretaceous slope in the lower part of the Banquereau Formation. The Avondale Member corresponds to small sand-prone submarine fans deposited on the basin floor in the early Paleocene. The submarine fans were fed primarily by two canyons that incised the western margin of the basin, eroding the Late Cretaceous shelf and slope. Also in the Paleocene, siliceous shale and siltstone of the Tilton Member were deposited above bathymetric highs along the western and southern basin margins. The exact temporal relationship between the Tilton and Avondale members is poorly understood. The South Mara Member was deposited in the latest Paleocene and early Eocene. In the southern parts of the basin, it forms a regressive sandstone unit above the Tilton Member, deposited during a period of renewed shelf-slope progradation. In the central and northern parts of the basin, the South Mara Member corresponds to small, sand-prone submarine fans, similar to those deposited in the early Paleocene. Mark Deptuck holds a B.Sc. honors degree in geology from Saint Mary's University (1998) and is currently a Ph.D. candidate at Dalhousie University, spending much of his time collaborating with researchers at the Geological Survey of Canada (Atlantic). His primary research interests include the offshore Mesozoic and Cenozoic evolution of eastern Canada and the depositional processes and architecture of modern and ancient submarine fans.Andrew MacRae has a B.Sc. degree from Dalhousie University in Halifax, Nova Scotia, and an M.Sc. degree and Ph.D. from the University of Calgary, Alberta. He worked at the Geological Survey of Canada (Atlantic) for five years and currently teaches at Saint Mary's University in Halifax. His research interests include Cretaceous and Cenozoic palynology and sequence stratigraphy in the Arctic and the offshore of eastern Canada, tidally influenced sedimentary environments, chalk facies, and brackish-water dinoflagellates. In collaborative research projects with industry and the academe over the past eight years, John Shimeld has interpreted a variety of 2-D and 3-D seismic data sets acquired offshore eastern Canada. His research interests include polygonal faulting, shallow- and deep-water depositional systems, and salt tectonics. He received a B.A.Sc. degree from the University of Waterloo in 1991 and an M.Sc. degree from Dalhousie University in 1994. Graham Williams is a palynologist whose main focus is the Mesozoic–Cenozoic biostratigraphy of offshore eastern Canada. His fascination with dinoflagellates has led to studies of these microfossils in both hemispheres, including some of the deep ocean basins. After seven years with Pan American Petroleum (for anyone who remembers that far back), Graham joined the Geological Survey of Canada (Atlantic) in 1971. Rob Fensome is a research scientist at Natural Resources Canada (GSC Atlantic) specializing in palynostratigraphy of offshore eastern Canada. Educated at Nottingham University and the University of Saskatchewan, Rob's other main interests are dinoflagellate evolution, outreach, and the geological history of the Maritime Provinces of Canada, recently coediting a book on the last subject (with Graham Williams).