Correlation of the Cretaceous-Paleocene Strata of Bylot Island, Nunavut and West Greenland

James Haggart

Thick deposits of Cretaceous-Tertiary strata in Baffin Bay, thought to have significant petroleum potential, have been the focus of stratigraphic research in both CA and DK. Onshore analogues for offshore West Greenland strata are found on Disko Island, Svartenhuk Halvø, and Nuussuaq Peninsula (Nuussuaq Group). In western Baffin Bay, the only significant onshore analogues for the Baffin Shelf are found on Bylot Island and adjacent Baffin Island (Eclipse Trough and North Bylot Trough). The Cretaceous-Tertiary strata of Bylot Island consist of >1.5 km of alternating fine- and coarse-grained clastics in sections that are challenging to correlate. Palynostratigraphy, using spores, pollen, and dinoflagellate cysts, has identified ten preliminary floral assemblages useful for correlation. These are approximately late Albian-Cenomanian, late Coniacian, late Coniacian-early Santonian, Santonian, Campanian, Maastrichtian, early late Maastrichtian, earliest Paleocene, early Paleocene (Danian) and mid-Paleocene (Selandian); other assemblages may ultimately be recognized. Initially, sedimentation was in marginal marine and deltaic environments. Subsequently, 400 m of Cenomanian-lower Maastrichtian shelf to upper slope mudstone was covered by 900 m of prograding upper Maastrichtian-Paleocene coarse clastics, showing transition northward from non-marine and fan-delta environments into time-equivalent deeper water submarine-fan environments. Upper Paleocene strata consist of c. 60 m of marine(?) black mudstone. The Bylot Island succession may contain one or more unconformities and the lack of distinct early Maastrichtian fossils may reflect a depositional hiatus or period of erosion. Variations in stratigraphic and provenance data suggest the Eclipse Trough / North Bylot Trough successions evolved independently beginning in the latest Cretaceous, possibly reflecting localized uplift. In comparison with Bylot Island, the Cretaceous-Tertiary succession of the Nuussuaq Basin of West Greenland is a thicker deposit (c. 3 km), with marked facies variations. Strata are considered to represent syn-rift, post-rift, and drift successions related to Baffin Bay spreading. Eleven palynostratigraphic intervals are recognized in the Cretaceous succession, representing late Albian, Coniacian-early Santonian, late Santonian-early Campanian, early-middle Campanian, late Campanian, early Maastrichtian and late Maastrichtian; the Paleocene has been further subdivided into five intervals. In West Greenland, correlation of fluviatile, marginal marine, and deltaic deposits is difficult, and the scarcity of diagnostic species restricts the biostratigraphical resolution. West Greenland outcrops are correlated with seismic sequences from offshore, where geophysical data suggest high sedimentation rates, with a Mesozoic section at least 6 km thick. Many of the rocks of West Greenland and southern Baffin Bay are covered with a widespread Paleocene-Eocene volcanic cap. Although the biostratigraphic frameworks of western and eastern Baffin Bay have yet to be tested and applied extrabasinally, many taxa recognized are known from both areas and may together contribute to better regional correlations of interfingering fluviatile, marginal marine, deltaic, shelf and deep water marine deposits. As well, ongoing provenance studies have shown that local as well as distant sources have contributed to the siliciclastic sediments in both regions

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013