Sedimentology, Paleoecology and Diagenesis of Mudmound Reefs on an Upper Devonian (Frasnian) Ramp, Western Alberta, Canada
Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada
The Mount Hawk Formation in the Willmore Wilderness Park of west-central Alberta consists of fossiliferous limestones deposited in a deep shelf to ramp setting. It hosts two well exposed, structurally undeformed, massively bedded patch reefs. They are mudmound type reefs composed dominantly of microcrystalline calcite with only scattered fossils like corals and are riddled with cavities cemented by fibrous calcite which precipitated out of seawater. Apparent offset of underlying strata directly under one of the reefs suggests the presence of a normal fault. The study mainly focuses on the make-up of the reefs and adjacent strata in order to: (1) determine the contrasting paleoecology and its evolution as the reefs grew and attained maximum relief of ~25 m from the sea floor; (2) map the internal framework fabrics across and through each reef; and (3) determine the geochemical (especially stable isotopic) compositions of the calcite cements and biotic elements. The aims are to: (1) detect the bathymetric signal in the biotic composition, if present; (2) determine the process of reef framework formation and ecological development that led to its accretion; and (3) reconstruct the diagenetic steps that led to lithification and to detect a possible role of subsurface fluids issuing from underlying faults. Results of the project will provide a dynamic model of sedimentary processes and reef development in the deep shelf/ramp setting as a guidance to exploration activities of adjacent subsurface and also help to understand porosity evolution and architecture of mud mound as a potential reservoir.
AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects