Sedimentology, Paleoecology, and Diagenesis of Mudmound Reefs on an Upper Devonian (Frasnian) Ramp, Western Alberta, Canada

Abstract

The Mount Hawk Formation in the Willmore Wilderness Park of west-central Alberta consisting of fossiliferous limestones was deposited in a deeper water setting, seaward of the platform margin behind which shallow water conditions prevailed. This is a unique outcrop since it hosts two well exposed, structurally undeformed, massively bedded patch reefs. They are mudmound type reefs composed dominantly of microcrystalline calcite with richly bioclastic fossils like corals and are riddled with cavities cemented by fibrous calcite which precipitated out of seawater. The reefs are flanked and overlain by fossiliferous thin- and medium-bedded limestones. The study determines the microfacies of these two mudmound reefs as they grew and attained relative high relief from the sea floor, in the context of the microfacies of the flanking and overlying strata, in order to detect in the biotic composition the bathymetric signal and its evolution and also determines the geochemical (especially stable isotopic) compositions of the calcite cements and biotic elements as a proxy for water-column productivity. Comparison can then be made to relative sea-level change recorded in the subsurface.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015