ABSTRACT

An outstanding aerial photograph of northern Grinnell Peninsula, Devon Island is reproduced with a geological interpretation. The area was occupied by three successive depositional basins: the Franklinian Miogeosyncline, the Arctic Platform and the Sverdrup Basin. Remnants of all three are preserved. The exposed section is more than 3300 m (11,000 ft) thick, including 12 Ordovician to Cretaceous map units and six unconformity surfaces.

Three major deformations produced two intersecting structural trends. The Cornwallis Fold Belt developed first, with deformation ending in Late Devonian time. Its northerly trend was rejuvenated and influenced all younger structures.

The Ellesmerian Orogeny occurred between Late Devonian and mid-Pennsylvanian time and included two phases. The first phase included a southward compression that put an east-west overprinting on northern parts of the Cornwallis Fold Belt. It apparently occurred before deposition of the Mississippian Emma Fiord Formation. This is a shaly and coaly transitional unit representing the earliest stages of the Sverdrup Basin. It apparently filled topographic lows in a fresh-water lake, as subsidence followed the first phase of folding.

The second phase of the Ellesmerian Orogeny was contemporaneous with marked regional downwarping that developed the Sverdrup Basin. The phase was marked at Lyall River by folding and faulting near the zone of flexure. The topographic relief created provided coarse conglomerate to the contemporaneous Canyon Fiord Formation.

A narrow east-trending, furrow-shaped high within the Sverdrup Basin was emergent through Canyon Fiord deposition. South of this high and largely cut off from the main basin was the narrow Lyall River Embayment of the Sverdrup Basin. The early history of the Sverdrup Basin was influenced greatly by pre-existing structure. The flexure that produced the basin caused an abrupt increase in the northward plunge of the Cornwallis Fold Belt.

Numerous normal faults exposed in the area probably were active in the Cretaceous-Tertiary Eurekan Orogeny. They were controlled by older structures.