A provenance study of Upper Jurassic hydrocarbon source rocks of the Flemish Pass Basin and Central Ridge, offshore Newfoundland, Canada

Scott, Matthew William (2018) A provenance study of Upper Jurassic hydrocarbon source rocks of the Flemish Pass Basin and Central Ridge, offshore Newfoundland, Canada. Masters thesis, Memorial University of Newfoundland.

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Abstract

This project is a provenance study of Upper Jurassic source and reservoir rocks from the Flemish Pass Basin and Central Ridge, offshore Newfoundland, Canada. It is aimed at adding a new dataset to contribute to our understanding of the geology of this area, where a number of recent hydrocarbon discoveries have been made, but limited geological information is available. A primary goal of the project is to determine the provenance and paleodrainage patterns of the Upper and Lower Kimmeridgian Source Rock and Upper and Lower Tempest Sandstone of the Flemish Pass Basin and the Central Ridge. It is likely that the source rock and reservoir units increase in thickness toward their source terranes and this provenance study would thus help define where thicker sequences of hydrocarbon source rocks and reservoir units are located in the region. In total, sixty samples of both mudstones and sandstones were acquired, processed and analyzed from four wells (Baccalieu I-78, Panther P-52, South Tempest G-88 and Lancaster G-70) to determine provenance. A combination of detrital zircon geochronology, whole rock geochemistry, and heavy mineral proxies were used to decipher provenance. In addition, core logging and thin section descriptions were completed to gain an understanding of the depositional environment. This analysis indicates a basinal setting with sediment being delivered by turbidity currents. The Upper Kimmeridgian Source Rock, Lower Kimmeridgian Source Rock and the Rankin Formation are interpreted to be composed of detritus from the Avalon Zone, Central Mobile Belt, and underlying basement. Detritus would have been derived from the northeast, and thicker sequences of these units would be expected in the northeastern portions of the Flemish Pass Basin and Central Ridge. The Upper Tempest and Lower Tempest Sandstone are also characterized by material from the Avalon Zone. However, some of the detritus from these units is also interpreted to be derived from Iberia to the east. In addition, the Upper Tempest Sandstone contains Mesozoic zircons, which helped constrain the depositional age of this unit. Mesozoic zircons were not found in samples from the other units. The Tempest Sandstone units are interpreted to be derived from the east, which means thicker sequences of this unit would be expected towards the eastern edges of the Central Ridge and Flemish Pass Basin. Knowledge of where the thickest packages of these units exist may be an important consideration for petroleum exploration in the region. In addition to these provenance findings, another important conclusion is that although provenance analysis methods such as detrital zircon geochronology are more common in sandstones, it is evident that using these techniques to analyze fine-grained sedimentary rocks is indeed feasible and useful. Additionally, the detrital zircon distributions in interbedded sandstone and mudstone beds were compared. These distributions suggested provenance of these pairs is very similar, an important implication for future use of this method in mudstones.

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