A New Map of Upper Paleozoic Formations, Raanes Peninsula, SW Ellesmere Island: Evidence for Tertiary Strike-Slip Deformation

Benoit Beauchamp
Department of Geoscience, University of Calgary, Calgary, AB, Canada.

Some 40 years after a map of Raanes Peninsula, SW Ellesmere Island, was first published (GSC Map 1300A - Eureka Sound Sound), a new map of the area around Blind Fiord and Trold Fiord is here released for the first time. This map focuses on Upper Paleozoic formations of the Sverdrup Basin and their relationships to surrounding older Franklinian strata and younger Mesozoic formations. This map is based on several field expeditions to the area between 1984 to 2010 by the authors and his students and collaborators with the Geological Survey of Canada and a number of universities. The map highlights a number of geological and stratigraphic elements that can be summarized as follow: (1) Ordovician, Silurian and Devonian units from the Franklinian Basement mapped west and east of Trold Fiord include the Christian Elv, Baumann Fiord, Eleanor River, Bay Fiord, Thumb Mountain, Irene Bay, Cape Phillips, Devon Island and Danish River formations. (2) Middle to latest Devonian deformation associated with the Ellesmerian Orogeny led to (i) symmetrical thrust-bounded synclines and anticlines above a detachment surface within the Baumann Fiord Formation; (ii) a 60 km-long east-verging overturned syncline (Trold Fiord Syncline), the axis of which runs parallel to Trold Fiord; and (iii) a series of tightly folded, several time repeated trust sheets of the highly contorted Thumb Mountain and Irene Bay carbonates overthrusted over the western limb of the Trold Fiord Syncline. (3) Extensive erosion and peneplanation of uplifted Franklinian strata occurred prior to Sverdrup Basin rifting. (4) Extensional inversion of Ellesmerian thrusts led to fault-controlled subsidence and creation of two rift-related down-to-the-basin half grabens - North Trold Fiord Depression (NTFD) and West Trold Fiord Depression (WTFD). (5) Compressional reactivation of Ellesmerian Thrust (Melvillian Disturbance) led to the partial to complete exhumation of the NTFD. (6) Upper Paleozoic units show significant facies change from northeast to southwest. Mapped units include: Canyon Fiord, Belcher Channel, Nansen, Raanes, Trappers Cove, Great Bear Cape, Assistance, van Hauen, Trold Fiord, Degerböls, Lindström and Black Stripe formations. (7) A series of NW-SE oriented Cretaceous mafic dykes intruded the area. (8) An early phase of Tertiary Eurekan deformation led to widespread regional uplift yet minor thrusting along two major structures - Blind Fiord Thrust (BFT) and Trold Fiord Thrust (TFT). (9) A later phase of Eurekan deformation led to 8 kms of dextral strike slip displacement along BFT and as much as 18 kms along TFT. As a result, the various Upper Paleozoic facies fronts associated with each low-order sequence are offset across BFT and TFT, while Cretaceous dykes align perfectly in a broad S-shaped sigmoidal pattern when displacement is restored along BFT and TFT. Double plunging tight folds occur in the immediate vicinity of TFT attesting for the intensity of strike slip deformation.

 

AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.

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