Tulluk High: An Inverted Multifold Structure and Potential Giant Megaprospect, Offshore Mackenzie Delta, Canadian Beaufort Sea
Geological interpretation of a 5-year 2D regional deep seismic survey in the Canadian Beaufort Sea has built a picture of a giant anticlinorium 150 km long and up to 50 km wide, the Tulluk High, that involves the 15 km thick Cretaceous and Tertiary clastic strata of the offshore Mackenzie Delta. This structure forms the frontal zone of the Beaufort Foldbelt, a marine compressional belt that propagates north from the active Alaska-Yukon Cordillera, overprints the passive margin wedge of the Arctic Ocean, and terminates eastward at the Tuk transform system.
The Tulluk High generally consists of 3 to 7 detachment anticlines of 5-7 km wavelength and 2 km structural relief, all of which are uplifted in a broad arch of 2+ km relief. The broad and deep uplift is inferred to be caused by inversion of the faulted oceanic crustal structures of the underlying Canada Basin spreading center (Late Jurassic to Early Cretaceous age range) based upon evidence from the 40 km deep PSDM seismic data and gravity: 1) the High is oblique to the foldbelt but parallel to a gravity low of the spreading center in the oceanic crust to the north; 2) a volcanic ridge imaged on 3 outboard lines and parallel to these trends forms a buttress on the northeast side of the High; 3) Miocene strata are thin to absent over the High and this unconformity defines and dates the broad inversion.
Industry clearly recognizes the potential of this megaprospect. Prospectivity is confirmed by tests of the Kopanoar sub-structure drilled over 30 years ago in 50 m of water, and is further supported by seismic data to the northwest in water depths to 2000 m displaying DHI’s and mud volcanoes. This unique and giant composite structure possesses all the credentials of a megaprospect in the proven petroleum system of the Canadian Beaufort Sea.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California