Geodynamic generation of a Paleocene–Eocene landscape buried beneath North Bressay, North Sea

Abstract

Histories of vertical lithospheric motions provide important clues about geodynamic processes. We present evidence of an ancient ( c. 58–55 Ma) landscape that probably underwent rapid uplift and subsidence during the initiation of the Icelandic plume. Now buried beneath c. 0.4–0.8 km of rock in the North Bressay region in the North Sea, this landscape is located within a sedimentary basin on the margin of the North Atlantic Ocean. We use high-resolution 3D seismic reflection data to map this ancient surface. Correlation of stratigraphy with a survey in the Bressay region constrains the age and depositional environment. The landscape contains excellent evidence of meandering fluvial channels, some of which record avulsions, that terminate against a coastline to the east where deltaic landforms are identified. The landscape was depth-converted and decompacted to generate a digital elevation model from which river profiles were extracted. Their geometries indicate that the landscape was generated by three phases of uplift. This history of uplift and subsidence is analogous to similar-aged landscapes in the Judd area c. 400 km to the west and Bressay c. 30 km to the south, and appears to be another manifestation of lithospheric motions generated by the passage of warm thermal anomalies away from the Icelandic plume.