Teegan Ojala HBSc thesis abstract

Thesis Title: 
Sequence Stratigraphic and Architectural Analysis of a 1.83 Ga Turbidite System: The Rove Formation, Northwestern Ontario

The Paleoproterozoic (1.83 ± 0.01 Ga) Rove Formation forms the upper sedimentary unit within the Animikie Basin of the Superior Province. The Rove Formation is underlain by the Paleoproterozoic Gunflint Formation (1.878 ± 1 Ga), which contains the Sudbury Ejecta Layer near its upper contact. The ejecta layer is composed of debris from the Sudbury impact (1850 ± 1 Ma) and fragments of the Gunflint Formation.

The Rove Formation is a turbidite succession with characteristics of both turbidite system end-member models: submarine fans and ramps. Sediment input to the submarine system was from the north-north-west, with the likely source being the Trans-Hudson Orogen. The Rove Formation was deposited within a basin created by crustal subsidence associated with the Trans-Hudson Orogen, which was forming at the time of Rove Formation deposition.

This study involved the examination of approximately 1340 m of previously unexamined drill-core from five holes and reexamination of approximately 4840 m of previously examined drill-core from ten holes, totaling 6180 m of drill-core. The data from the drill-cores were used to create a series of stratigraphic diagrams in order to allow detailed architectural and sequence stratigraphic analysis of the Rove Formation to determine if the traditional submarine fan or ramp models match its stratigraphy. The drill-cores examined were drilled southwest of Thunder Bay, Ontario, in an area approximately 50 km wide between Thunder Bay and the United States Border. Architectural analysis of the Rove Formation indicated that the Rove is similar to submarine fan systems in that some well-structured depositional lobe and channel sequences are present. However, it also indicated that most of the system is more chaotic and relatively poorly structured, similar to submarine ramp systems. Furthermore, it was determined that the Rove Formation was fed by a delta coming of a braided river system and that there was not a singular point source of sediment input, as in submarine fans, but a linear sediment source and multiple feeder channels existed, similar to submarine ramp systems. Sequence stratigraphic analysis of the Rove Formation showed that there were a large number of transgressive sequences, represented by condensed shale intervals, within the Rove, indicating that relative sea-level was variable during its deposition.

While it was determined that the Rove Formation does have characteristics of both submarine fans and ramps, the architecture of the Rove does not fit either model well. This indicates that the traditional turbidite system models may be flawed and that these systems may need to be re-examined and re-interpreted using more extensive and complete data sets, similar to the data set used for this study.