Seismic and Biostratigraphic Analysis of the Upper Cenozoic Deep Water Iperk Sequence in the Beaufort-Mackenzie Basin, Arctic Canada

Gillian Q. Chi¹ and David H. McNeil^2
1University of Calgary, Calgary, AB, Canada.
²Geological Survey of Canada, Calgary, AB, Canada.

Seismic-stratigraphic and biostratigraphic studies of the Upper Cenozoic Iperk Sequence provide new insights into depositional patterns and petroleum reservoir potential in mid-Pliocene to Pleistocene (pre-Wisconsin) strata in the Beaufort-Mackenzie Basin. Eight stratigraphic subsequences are identified in the Iperk Sequence, each recording discrete episodes of basinward shelf margin progradation and associated shelf to deep-water sedimentation. The palynological and foraminiferal records indicate dry, cool climatic conditions during the Late Cenozoic.

Regional stratigraphic and sedimentological analyses indicate the source terrains for mid Plio-Pleistocene deposits were from tectonically uplifted areas of the Richardson Mountains to the south of the Beaufort-Mackenzie Basin. In the central and western part of the basin, thickness variations in the succession are related to changing point sources, with a main feeder axis oriented southeast to northwest during deposition of the oldest subsequences. Tectonic uplift in the western part of the basin forced a slight change in the directions of the main feeder axis of the younger subsequences, from southeast gradually into southwest.

Offshore wells drilled in the northern Beaufort-Mackenzie Basin encountered variably thick sections of fine-grained turbidite sandstones in the Iperk Sequence. Deposition of turbidite deposits and associated channels in the lower Iperk subsequences was controlled by numerous ponded mini-basins generated from the growth of the deep-seated Tertiary fold structures in the mid-slope, toe-of-slope, whereas in the basin plain turbidite flow was restricted by underlying Tertiary highs and turbidite lobes with channels were deposited in the topographic lows. High rates of sediment flux formed low gradient slopes in the upper part, resulting in toe-of-slope and basin floor turbidites with channel fills. Potential structural-stratigraphic traps are present in these fan and channel complexes along the continental slope and potential stratigraphic traps are dominant in basin plain area.

Acknowledgements
This study is the result of collaboration between the co-authors with contributions from James Dietrich, Zhuoheng Chen and Jim Dixon and was conducted at the Geological Survey of Canada as the part of research in the Mackenzie Delta and Corridor project of the Geo-Mapping for Energy and Minerals Program (GEMS). We would like to thank John Harper, Director of Geological Survey of Canada (Calgary), for his support to publish. Thanks also to Dr. Ashton Embry for his insight and good suggestion and to Bernie MacLean, Tom Brent, and Philip Lawrence for geophysical support. A special thank to Dr. Rob McNaughton, the leader the Mackenzie Delta and Corridor project for his support.

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