Does the Rotational Opening of the Canada Basin Imply a Marine Connection between the Sverdrup Basin and Hanna Trough?
Stansilaw Mazur, Simon Campbell, Rkia Bouatmani, Kathelijne Bonne, Lawrence Gill, and Paul Markwick
GETECH, Leeds, United Kingdom.
The prevailing plate model for the Arctic explains the opening of the Canada Basin through 66° of anticlockwise rotation of Arctic Alaska and Chukotka away from the Canadian Arctic Islands about a pole in the Mackenzie Delta region. The validity of this hypothesis has been frequently supported by the palaeogeographic reconstruction showing the direct pre-Cretaceous continuity of the Sverdrup Basin into the Hanna Trough. We test the justification of an early Mesozoic marine connection between the Sverdrup Basin and Hanna Trough using plate modelling, analysis of seismic data and examination of facies distribution.
Our plate reconstruction for the Canada basin is a variation of the rotational model, but modified to avoid a large continental overlap between the Chukchi and East Siberian Shelf on one side and the Canada Arctic Islands on the other. The plate model was used to reverse the plate movements and restore the original early Mesozoic facies pattern. Available seismic data allow identification of areas of early Mesozoic uplift and erosion where the Ellesmerian sequence is missing and the Beaufortian and/or Brookian sequences directly overlay the Franklinian basement. These data show the lack of a possible connection between the Alaska passive margin and the Sverdrup Basin for most of the time between Carnian and Aptian due to a belt of uplifts along the Barrow Arch and the South Chukchi Basin. This is supported by the presence of a distinct basement high offshore modern day Arctic Alaska observed on early Mesozoic reconstructions of the gravity anomaly map.
The facies distribution indicates that an open ocean connection to the Sverdrup Basin and other shallow seas located at the northern Chukchi Shelf existed across present-day eastern Siberia. The presence of a deep seaway in that area is suggested by the widespread occurrence of turbidites throughout the majority of the Chukchi Platform. Furthermore, after reversing the rotation experienced by the Chukchi microplate, these turbidites must have been originally deposited in the area located close to eastern Arctic Canada. Geochemically and lithologically, key Late Triassic source rocks of the Shublik Formation (Alaska) and the Schei Point Group (Sverdrup Basin) also seem to differ. Therefore, the open marine connection between the Sverdrup Basin and the Hanna Trough seems to be unlikely for the most of the Mesozoic even with an adaptation of a rotational model for the opening of the Canada basin.
AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia