Intersecting fold belts in the Bathurst Island region, Nunavut

Abstract

The Bathurst Island archipelago in the central part of the Canadian Arctic Islands, includes Bathurst Island proper and six other significant islands to north and west. This is the site of two intersecting fold belts: the northerly-trending Cornwallis Fold Belt and the westerly-trending Parry Islands Fold BeltSignificant components of the report area include Precambrian seismic basement, the Franklinian shelf (Cambrian to Devonian), a Middle and Upper Devonian clastic wedge, and outliers of the Sverdrup Basin (Carboniferous-Cretaceous). Total thickness of the Cambrian to Devonian succession is 7.6–8.8 km in the island group. Oldest identified strata are evaporites of the Middle Ordovician Bay Fiord Formation. These form a ductile decollement zone that at a depth of 4100–5500 m everywhere underlies thrust-folds. Above this are shelf carbonates, deep water mudrocks, and shallow to deep water strata associated with tectonic activity through the upper Silurian to Lower Devonian Cornwallis Fold Belt. The end of uplift-related deposition is marked by a transition to basin fill mudrocks, succeeded in the later Devonian by shelf-deltaic and fluvial sandstones and other clastic rocks.Structures of Cornwallis Fold Belt feature north and in part west-striking thrust panels and evidence of unroofing in early Ludlow to mid-Emsian time. Also included are westerly-transported thrusts kinematically linked to easterly- striking wrench faults that are presumably reactivated as thrusts and forming large interference structures during development of Parry Islands Fold Belt deformation in the Late Devonian to early Carboniferous. Parry Islands Fold Belt features upright surface folds, subsurface thrusts, ductile deformation and detachment in Ordovician salt and Devonian shale. Structures include northerly- and southerly-transported thrusts, zig-zag structures, pop-up and pop-down structures.