Sedimentology and stratigraphy of the Cryogenian (middle Neoproterozoic) Keele Formation, Mackenzie Mountains, Northwest Territories

The ∼700 Ma Keele Formation is a succession of mixed carbonate and siliciclastic rocks, ∼300–600m thick, within the Windermere Supergroup of northwestern Canada. The Keele Formation was deposited during the Cryogenian period between Sturtian and Marinoan “global” glaciations. Strata are dominated by oolitic grainstone facies, and contain locally high concentrations of coarse siliciclastic fluvial sandstones. An informal member, the Keele Clastic Wedge, comprises the upper third of the formation and represents a sedimentary prelude to Marinoan glaciation.; Lateral and vertical arrangement of facies suggest deposition in a ramp setting, rather than a rimmed or flat-topped platform. Deep-water, outer-ramp facies include bituminous limestone and silty lime mudstone. Ooid-peloid grainstone facies typify the middle ramp, Peritidal laminites characterize inner ramp facies and contain lithologic indicators of subaerial exposure. Stromatolites are rare in Keele rocks. Carbonate strata are similar to Phanerozoic warm-water carbonates because they contain abundant originally aragonitic ooids and have well-developed muddy peritidal facies. Paleomagnetic data corroborate the interpretation that Keele rocks were deposited at tropical latitude. (Abstract shortened by UMI.)...