Lithofacies and diagenesis of the Cooking Lake platform : carbonates, Alberta Basin subsurface, Canada

• Main Author: Chouinard, Hugo
• Other Authors: Mountjoy, Eric (advisor)
• Format: Others
• Language: en
• Published: McGill University 1993
• Subjects: Geology.
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69588

The Cooking Lake Formation in east-central Alberta is a widespread sheet-like carbonate unit that is up to 100 m thick. === The lithofacies of the Cooking Lake Formation platform are assigned to eight depositional environments: (1) deep subtidal argillaceous calcimudstones, (2) deep to shallow subtidal nodular wackestones, (3) intermediate subtidal skeletal lime wackestones, (4) intertidal stromatoporoid/coral floatstones to rudstones, (5) shallow subtidal to lagoonal Amphipora floatstones, (6) shallow-shoal grainstones, (7) semi-restricted shallow subtidal peloidal wackestones/packstones, and (8) upper intertidal to supratidal laminated grainstones to algal-laminated limestones. === Near-surface diagenesis is characterized by rim, syntaxial, equant and blocky calcite cements. During shallow-burial diagenesis, replacement dolomite and compaction features such as stylolites and dissolution seams developed. Intermediate to late-burial diagenesis is characterized by anhydrite, coarse-crystalline and saddle dolomite cements and late, coarse-crystalline calcite cements. === Replacement dolomite and later dolomite cements occur across the entire platform but it is less important in the more muddy middle member. Petrographic and stable isotope data suggest that replacement dolomite formed during shallow-burial diagenesis associated with compaction features. Massive replacement dolomite only occur close to the dolomitized Rimbey-Meadowbrook reef trend. === The highest porosity (interparticle) occurs in the peloidal grainstone facies. Submarine equant and blocky calcite cements appear to be the most abundant cement whereas replacement dolomitization, dissolution, and fracturing slightly increased porosity, except in the massively dolomitized facies. The western part of the platform, which is massively dolomitized, may have served as an aquifer for the dolomitizing fluids.