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Seismic Mapping of the King Christian Formation, Sverdrup Basin, Arctic Canada: Spatial Visualization with Potential Field Data

Tom Brent2, Gordon N. Oakey3, and Christopher Harrison1
1Geological Survey of Canada - Ottawa, Ottawa, ON, Canada.
2Geological Survey of Canada - Calgary, Calgary, AB, Canada.
3Geological Survey of Canada - Atlantic, Darmouth, NS, Canada.

Both new and legacy seismic interpretations which map subsurface structure at the stratigraphic level of the early-Jurassic King Christian Fm in the Sverdrup Basin, have been compiled. Visualization with GIS technology of this structural surface in two way time is presented and extends over much of the entire western part of the Sverdrup Basin from Prince Patrick Island to Ellef Ringnes Island. Evident are both low and high relief structures, the latter thought to be cored with evaporities of the Carboniferous Otto Fiord Fm. Some of these salt structures pierce the entire Sverdrup stratigraphy to surface or sea floor and influence sedimentary accommodation through the late Jurassic to present. Most faults mapped at this level are extensional with the exception of reverse faults beginning to appear east of Cornwall Island, in the Norwegian Bay area. The map illustrates the general structural context of the 17 hydrocarbon discoveries to date in the Sverdrup Basin. This seismically-mapped surface is shown integrated with sun-illuminated relief overlain with color fill representing magnetic anomaly. The resulting data integration image shows the spatial coincidence of magnetic anomalies with mapped subsurface structure of the King Christian Formation and some of the larger magnetic features may be a indication of considerable intrusive emplacement at depth, which may have influenced local thermal maturity of sediments, such as the large magnetic anomaly east of the Cisco hydrocarbon discovery. Other features, such as NE trending linear magnetic lineaments are observed to trend coincident with extensional faults (grabens). These magnetic anomalies, interpreted to be dykes at depth, have previously been suggested to have created subsurface voids, allowing the graben formation of the overlying sedimentary section. Also shown is seismic-derived sea floor relief within the inter-island channels, and a 220 km seismic profile in the offshore, acquired over permanent sea ice, which illustrates both data quality issues specific to the arctic environment, and possible seismic expression previously unrecognized diapirism. The time structure surface is corrected for the low-velocity effect of the variable water column within the inter-island channels, but not for the permafrost velocity effect at the shoreline of the islands. Most permafrost velocity effects at shorelines are small (<40 ms) but can be in excess of 140 ms.

 

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