Abstract

In the Talbot Lake area, the Upper Mississippian carbonate sequence comprises, in ascending order, the Turner Valley and Mount Head formations. The Mount Head Formation is informally divided into lower and upper members. The rocks of the Upper Mississippian originated by sedimentation associated with successive shallowing-upward sequences. On the basis of the fossils, lithologies, textural characters, and sedimentary structures, the Turner Valley Formation apparently resulted from sedimentation on open marine shoals and in a lagoon, the lower member of the Mount Head Formation from sedimentation in shallow subtidal to lower supratidal environments, and the upper member of the Mount Head Formation from deposition in upper intertidal to supratidal environments.The paraconformity between the lower and upper members of the Mount Head Formation records a short erosional break. A disconformity between the Upper Mississippian carbonates and the Upper Permian Ishbel Group displays paleotopographic relief and paleokarstic features developed during exposure in post-Mississippian times. The disconformity is overlain by a condensed sequence of Pennsylvanian to Permian strata.Major diagenetic modifications of the Upper Mississippian strata include dolomitization, silica replacement and cementation, carbonate cementation, and dedolomitization. A diagenetic realm comprising sea water, fresh water, and hypersaline brine was probably responsible for some of the complex diagenesis in these rocks.

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