Statistical measurements of organic and inorganic parameters in thin sections reveal that the Swan Hills Member of the Beaverhill Lake Formation in the Shell Swan Hills 10-17 well is made up by the rhythmical alternation of 8 carbonate microfacies. These rock-types are closely related and interpreted as a continuous sequence representing fore-reef, reef and back-reef conditions. The fore-reef environment shows dark-colored calcarenites whereas the reef itself consists of dark-colored bioconstructed limestones made up by cabbage-type stromatoporoids followed in shallower water by branching colonies of Amphipora. With these 2 organically constructed deposits are associated several types of biocalcarenites. The back reef environment is represented by light-colored calcilutites containing scattered colonies of Amphipora and of mat-type stromatoporoids. The vertical superposition of these microfacies displays 7 rhythms of sedimentation during which an Amphipora-stromatoporoid reef community was established over a carbonate platform, developed and eventually disappeared. The rhythms seem to correspond to tectonically controlled phases of depth decrease.

First Page Preview

First page PDF preview
You do not currently have access to this article.