Shallow marine sedimentation within an active margin basin, James Ross Island, Antarctica

• Published in: Sedimentary Geology
• Main Author: Pirrie, Duncan
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 1989
• Subjects: Weddell Sea; Ross Island; Weddell; Larsen Basin; Antarc*; Antarctica; James Ross Island
• Online Access: http://nora.nerc.ac.uk/id/eprint/521316/; https://doi.org/10.1016/0037-0738(89)90071-7

The Santa Marta Formation exposed on northern James Ross Island, Antarctica, represents shallow marine shelf sedimentation within an active margin basin. The formation is approximately 1000 m thick, is of uppermost Santonian to Campanian age and represents part of a 5000–6000 m thick sedimentary sequence forming the Larsen Basin. The Larsen Basin represents either a back-arc basin, or a half-graben basin, developed on the extending margin of the Weddell Sea. Twelve sedimentary facies have been recognised, which can be subdivided into two groups: those which are controlled by shelf processes and those which are related to active arc volcanism. Background shelf processes include fair-weather suspension sedimentation, storm sands and rare tidal current reworking. Active arc processes include direct settling of airfall detritus and rapid resedimentation of volcaniclastic detritus by sandy debris-flows and both high- and low-concentration turbidity currents. In addition sheet conglomerates represent debris flows that evolved from syn-sedimentary slumps. Two facies associations representing a mid to outer shelf and an inner shelf depositional setting respectively can be distinguished, with an apparent regression in the ?mid to late Campanian.