Cretaceous tectono-stratigraphic evolution of the Ribban and northern Træna basins at the Lofoten margin, offshore northern Norway

• Main Author: Wilhelmsen, Hanne Christine Rolstad
• Format: Master Thesis
• Language: English
• Published: 2016
• Subjects: Andøya; Greenland; Lofoten; Norway; Træna; Vesterålen; Greenland Sea; North Atlantic; Northern Norway
• Online Access: http://hdl.handle.net/10852/52353; http://urn.nb.no/URN:NBN:no-55780

The Lofoten margin segment is located offshore northern Norway, in between the volcanic rifted Vøring and Vesterålen margins. Several available datasets have been integrated in order to study in detail the tectono-stratigraphic evolution of the eastern part of the Lofoten rifted margin segment, comprising the northern Træna and Ribban basins, with main emphasis on fault evolution and the Cretaceous basin infill history. The utilized datasets include: available 2D multi-channel seismic reflection profiles; well-to-seismic ties and stratigraphic information from one exploration well and published information from all IKU shallow boreholes in the area together with the Andøya onshore outcrop; and gravity and magnetic data. Structural and stratigraphic interpretations have been conducted in order to obtain a picture of the basin architecture and evolution through time. Nine sequences ranging in age from Triassic-Early Jurassic to Cenozoic have been interpreted and analysed in terms of lateral geometries and vertical thickness variations, in order to detect important phases of tectonic activity and to better understand the interplay between faulting and deposition. The study area is dominated by NNE-SSW trending extensional basins and shelf-parallel basement ridges, generated from several phases of rifting. The northern Træna and Ribban basins have proven to be highly dynamic, with records of at least four main rift events. The basins developed within the context of the North Atlantic rift system, and are predominately filled with Cretaceous successions. Following the main Late Jurassic rift phase, these basins further evolved during the Early Cretaceous with extension continuing into earliest Cretaceous and a separate rift phase taken place during Aptian. Both tectonic events were followed by subsidence. Renewed rifting during Late Cretaceous-Early Tertiary times is mainly concentrated west of the study area, but some reactivation along the border faults of the northern Træna and Ribban basins are observed. This is related to the continental breakup and onset of sea floor spreading in the Norwegian-Greenland Sea at the Paleocene-Eocene transition. The first-order tectono-stratigraphic evolution of the Lofoten margin has been compared with the Vøring margin and the conjugate Northeast Greenland margin, and this reveals that the Lofoten margin experienced only moderate pre-breakup extension compared to the adjacent and conjugate margin counterparts. The conjugate mid-Norwegian and Northeast Greenland continental margins clearly show an asymmetrical crustal architecture, with the line of breakup being oblique to the Cretaceous basin trend and resulting in breakup at different locations with respect to the pre-existing rift systems on either side of the Bivrost transfer system.