Print this pageNew Seismic Data Integrated with Gravity Signatures Provide an Improved Picture of the Arctic Continental Margin from the Mackenzie Delta to the McClure Strait
Menno Dinkelman1, Dale Bird2, James A. Helwig3, Pete A. Emmet3, and Naresh Kumar3
1ION Geophysical - GX Technology, Houston, Houston, TX.
2Bird Geophysics, Houston, TX.
3Consultant ION - GXT, Houston, TX.
Our most recent Phase IV BeaufortSPAN™ seismic survey in the Canadian Arctic passive margin confirms and elaborates upon the tectonic framework established in our previous studies. The Canada Basin’s Beaufort-Mackenzie passive margin is clearly subdivided into three segments of different orientation: the overprinted compressional Foldbelt segment trending E-W to the west toward Alaska, the transtensional Tuk segment trending NE off the Tuktoyaktuk Peninsula, and the classic extensional Banks segment trending N off Banks Island.
The new seismic survey was shot in the summer of 2010 using specialized new technology for acquiring data in first-year ice-covered areas, and extended earlier coverage into water depths of between 500 to 2,500 m, as well as farther northeast than any previous survey. The infill data and extended coverage into deeper water permit significant new geological observations, including from southwest to northeast: 1) recognition that the Beaufort-Mackenzie foldbelt reaches north into areas previously mapped as undeformed; 2) recognition of a very deep (> 20 km) and rather rugose top of oceanic crust in the proximity of the presumed extinct spreading center inferred from gravity and sparse reflection data in the central Canada Basin; and, 3) imaging on at least six new lines of the continent-ocean transition offshore northern Banks Island and McClure Strait, including hints of compressional toe thrusts down-dip of shallower extensional break-away faults.
The southeastern slope to shelf boundary of the Canada Basin, from the Tuktoyaktuk Peninsula to northern Banks Island, is marked by a subparallel prominent free-air gravity high approximately 1,000 km in linear extent. The central part of the Canada Basin is defined by a northwest-trending regional gravity low of approximately 850 km linear extent. These two anomalies intersect at the Amauligak Trough. Some authors have described the central Canada Basin gravity low as an extinct oceanic spreading center. These structures are imaged in deepwater lines of our 2010 survey. Several new profiles across the Banks Island margin show that the continent-ocean transition indicated by the gravity anomaly coincides with the central part of a detached gravitational tectonic belt including a break-away and rollover normal fault system on the shelf to upper slope, and a linked compressional toe-thrust system in deep water down-dip of the extended margin.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.