Sedimentology and diagenesis of the Upper Devonian Kaybob stratigraphic reef
Creators: name: Wong, Pak Kheong
Publisher: name: University of Calgary
Year: 1978
Subjects: subject: QE 665 W65 1978 Microfiche
subject: Geology, Stratigraphic - Devonian
subject: Reefs - Alberta
subject: Diagenesis
subject: Sedimentation and deposition

description: Bibliography: p. 195-207.
description: The Kaybob stratigraphic reef, located in the subsurface of the Swan Hills area, is part of the Swan Hills Formation. Based on differences in colour, depositional texture, composition and distribution, sediments of the reef and adjacent areas can be assigned to six environmental fades. These are: the nodular limestone off-reef facies, the peloidal sand fades, the reef slope fades, the massive stromatoporoid reef margin facies, the branching stromatoporoid reef margin fades, and the reef interior facies. The reef margins were defined by either the branching stromatoporoid reef margin fades or, when turbulence was high, by the massive stromatoporoid reef margin facies. Ecologic patch reefs of in situ intergrowths of massive, tabular and branching stromatoporoids characterize the massive stromatoporoid reef margin fades. The reef interior facies consists of cyclical sequences of sub tidal and intertidal to supra.tidal sediments. These sequences do not extend into the adjacent branching stromatoporoid reef margin facies. Cyclicity can be accounted for by variations in carbonate production due to changes in the size of the source area. The restriction of the massive stromatoporoid reef margin facies to the eastern reef margin and the peloidal sand facies, composed of reef interior derived sediments, to the western side, suggests prevailing easterly winds during the second and subsequent phases of reef growth. Diagenesis occurred in the eogentic and mesogenetic realms. Eogenetic diagenesis is of vadose and phreatic, marine and fresh water origin. Marine phreatic diagenesis comprises burrowing, boring and cementation, whereas marine vadose diagenesis comprises dissolution and cementation. Fresh water vadose diagenesis is manifested in widespread dissolution, karsting, crystal silt deposition, brecciation and cementation. Fresh water phreatic diagenesis consists of dissolution and cement precipitation. Borings were created by a variety of organisms, probably worms, bivalves, fungi and/or algae. Bioerosion caused sediment generation and the removal and replacement of stromatoporoid by internal sediments. Mesogenetic diagenesis consists of compactional fracturing, pressure solution, cement precipitation and hydrocarbon emplacement. Three distinct generations of cements can be recognized. First generation, eogenetic cements are pre-pressure solution and pre-compactional fracture. The cements occur as isopachous and microstalactitic rims, precipitated in both marine and fresh water phreatic and vadose environments. Second generation, mesogenetic, zoned dolomite and calcite cements are syn-pressure solution and post-compactional fracture. Calcite cements, derived from pressure solution, were precipitated immediately adjacent to stylolites. Third generation, inesogene tic cements are niicrite sized and postpressure solution. The micrite cements were succeeded and arrested by hydrocarbon emplacement.