Petrology, geochemistry, diagenesis and depositional environment of the Upper Devonian - Lower Carboniferous Exshaw Formation, northwestern Alberta

The Upper Devonian (Famennian)-Lower Carboniferous (Tournaisian) Exshaw Formation is a thin, laterally extensive organic-rich petroleum source rock. It is one of Canada's most important petroleum source rocks and is a major contributor to the Lower Cretaceous Mannville heavy oil accumulations in the Western Canada Sedimentary Basin. The development of organic-rich deposits has been the center of much controversy as of late, since there are a number of depositional and paleo-oceanographic conditions responsible for their formation. This has led to various models attempting to explain the production and preservation of large quantities of organic matter.; The Exshaw Formation is composed of an upper siltstone member and a lower black shale member. For the purpose of this investigation only the lower black shale in the Tangent Field of the Peace River embayment (T80-R23W5) was studied. The lower black shale member of the Exshaw Formation can be divided into two informal units. The lower unit consists of a blocky, calcareous, pyritic shale with chert-rich laminations. This unit is generally more competent than that of the upper more fissile, non- to slightly calcareous shale. (Abstract shortened by UMI.)...