The Orphan Basin: A review of basin evolution, structure, stratigraphy and petroleum systems

The Orphan Basin, located offshore northeastern Newfoundland, Eastern Canada, is a Mesozoic rift basin formed during the disintegration of Pangaea and the concurrent opening of the North Atlantic Ocean. The majority of previous work has divided the basin into the East (EOB) and West Orphan (WOB) subbasins, separated by the Central Orphan High (COH). These subbasins share some similarities but have different opening kinematics, timings, and sedimentary histories. Despite its critical location at the termination of the Charlie-Gibbs Fracture Zone (CGFZ), and the transition from the main North Atlantic Ocean to the Labrador Sea, the Orphan Basin remains relatively poorly understood compared to other marginal rift basins in the North Atlantic region. Additionally, much of the public domain geoscientific literature on the basin has not undergone peer review (e. g., conference abstracts, industry reports, etc.). As such, the aim of this review is to critically scrutinize and synthesize the wealth of geoscientific information on the basin, present an overview of the complex structure of the basin and its sedimentary fill, identify knowledge gaps, and provide insights for future research directions. This review highlights that significantly more is known about the EOB than the WOB, largely due to data availability. Furthermore, structural inheritance appears to have strongly influenced the evolution and geometry of rift-related faults. Areas requiring further research include refining the timing and relationship between the opening kinematics of the EOB and WOB, particularly pertaining to the role of the Flemish Cap. Additionally, the continuation of sedimentary facies from the better constrained EOB into the WOB is currently poorly understood, especially for the syn-rift strata, which results in substantial exploration risk in the WOB. Understanding the WOB, including the magmatic rocks, is essential for understanding the wider southern North Atlantic region.