Facies analysis of Lower Permian cyclic carbonates, west-central Ellesmere Island, Canadian Arctic.

At least 36 decametre-scale, largely symmetric high-frequency cycles spanning approximately 15 Ma make up the carbonate-dominated succession of Lower Permian sequence 3 of the Sverdrup Basin in Fosheim and Hamilton peninsulas. These cycles record a rift pulse caracterized by the uplift, passive subsidence, collapse and passive subsidence of the Fosheim-Hamilton subbasin and show that during the rifting phase of the Sverdrup Basin deposition of conformity-bounded sequences was tectonically rather than eustatically controlled. The active rifting-phase of the Sverdrup Basin comprises four unconformity-bounded sequences that range in age from Visean to Kungurian. The third-sequence in Fosheim and Hamilton peninsulas area, west central Ellesmere Island comprises six formations. The Canyon Fiord Formation is composed of lithofacies ranging from basin margin fluvial to marine siliciclastics. The Belcher Channel, Antoinette, Tanquary and Nansen formations are made up of inner- to midshelf carbonates that encompass the Mount Bayley Formation, a thick evaporite succession deposited within the Fosheim-Hamilton subbasin. Petrographic analysis of the carbonate-dominated facies in sequence 3 has delimited nineteen platformal facies representing lagoonal, barrier and shoal, reefal and non-reefal mid-shelf depositional environments. These facies are organized into high-frequency depositional cycles that record the interplay between eustasy, tectonism and sediment supply. In order to facilitate their regional analysis, cycles were grouped into five idealized cycles. From proximal to distal, these cycles include: Sandstone-Grainstone; Grainstone-Palaeoaplysinid; Packstone-Phylloid; Wackestone; and Anhydrite cycles. These high-frequency cycles are grouped into a Pre-, Syn- and Post-evaporite cyclic assemblages, each of which possess an unique stacking pattern. The Pre-evaporite Assemblage comprises 9 cycles characterized by relatively similar thickness and composition. High-frequency cyclicity within this assemblage was controlled by glacio-eustatic oscillations with only local tectonic influence. (Abstract shortened by UMI.