TERTIARY STRUCTURAL EVOLUTION OF THE BEAUFORT SEA - MACKENZIE DELTA REGION, ARCTIC CANADA

Proterozoic to Tertiary sedimentary strata in the Canadian Beaufort Se a-Mackenzie Delta region were deformed into a regional fold and thrust belt during Tertiary orogenesis. Seismically-imaged fold structures a re commonly asymmetric and many are clearly detached. Decollement hori zons occur at several stratigraphic levels. The Tertiary Beaufort Fold belt developed as an arcuate array of contractional structures and ass ociated (coeval) longitudinal normal faults and oblique-slip fault zon es. The extensional and transcurrent faults accommodated variations in the direction and magnitude of Tertiary shortening. Tertiary deformat ion shows a general foreland-younging trend, away from the craton. The most intense pulses of Tertiary deformation occurred in the Early to Middle Eocene and Late Miocene. The Late Miocene pulse of tectonism af fected some parts of the region more than others, thus segmenting the region into variably deformed areas. The Tertiary structural evolution of the Beaufort Sea-Mackenzie Delta region reflects a complex interpl ay between crustal shortening, syntectonic sedimentation and an array of boundary conditions imposed by basin margins and pre-existing basem ent structures. Basement controls on Tertiary deformation appear likel y in some parts of the region.