Ponding and compartmentalization of a giant Paleogene slope fan by mass transport complexes, offshore Newfoundland, Canada

• Published in: Marine and petroleum geology Vol. 167; p. 106939
• Main Authors: Henry, Lindsey C., Faerber, Ryan D., Steinhoff, Doerte, Bolivar, Maria, Browning, Emily
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2024
• Subjects: Channel-lobe complexes; Mass transport deposits; Newfoundland; Ponding; Turbidites; West orphan basin; West orphan basin; Channel-lobe complexes; Newfoundland; Mass transport deposits; Ponding; Turbidites
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/j.marpetgeo.2024.106939

The Ephesus fan is a giant channel-lobe complex that extends across 460 km2 in the lower structured slope of the West Orphan Basin, offshore Newfoundland, Canada. Based on biostratigraphic dating of offset wells, the fan was likely deposited during the Oligocene. High resolution 3D seismic data reveal that the fan overlies a succession of mass transport deposits that initially created a flatter topographic surface, with later slumping events building elongated ridges. Subsequent high density turbidity currents coursed into the area through a single feeder channel, depositing as lobes onto the flatter area via a network of distributary channels. The lobes were circumferentially ponded and internally compartmentalized by the slump ridges, and the ponding forced the fan to assume its unique, 46 km-wide shape. Distributary channels were initially directed to the south side of the fan, due to the higher relief of the mass transport deposits to the north. After the infill of the accommodation space to the south, subsequent sediment input levelled the remaining rugose topography, and some distributary channels were able to avulse north. Throughout deposition of the fan, distributary channels also continued down-dip from the lobe complex, indicating some sediment bypass continuing down the lower slope. Overlying laminated mudrock displays pervasive polygonal faulting, signaling dewatering processes and the end of deposition by muddy submarine landslides and high density turbidity currents. •The Ephesus fan is a channel-lobe complex that extends across 460 km2 in the lower structured slope of West Orphan Basin.•Based on biostratigraphic dating of offset wells, the fan was likely deposited during the Oligocene.•The MTCs flattened the lower slope and formed a series of ridges, which ponded the fan into its unique, wide shape.•Overlying mudrock displays polygonal faults, signaling dewatering and the end of MTC and high density turbidite deposition.