Late Mesozoic-Cenozoic tectono-stratigraphic evolution of the Vesterålen margin, offshore northern Norway

• Main Author: Meza, Juan Camilo
• Format: Master Thesis
• Language: English
• Published: 2020
• Subjects: Andøya; Greenland; Lofoten; Norway; Vesterålen; Northern Norway
• Online Access: http://hdl.handle.net/10852/79770; http://urn.nb.no/URN:NBN:no-82912

Available 2D multi-channel seismic profiles and a 3D seismic survey are utilized together with potential field and limited well data to study the Late Mesozoic-Cenozoic tectono-stratigraphic evolution of the Vesterålen margin offshore northern Norway. The analysis resulted in an updated structural and stratigraphic framework, together with new and better refined structural elements for the Vesterålen margin. Distinct along-margin basin segmentation is evident through NW-SE trending curvilinear transfer zones informally named as the Jennegga transfer zone, Vesterålen transfer zone system, and Andøya transfer zone. These divide the study area into three main margin segments, namely the northern Lofoten, Vesterålen, and Andøya segments. Five main rift phases of varying intensity have been recognised and refined, and they are evidenced by eight mapped fault families: pre-Jurassic, Late Jurassic-earliest Cretaceous, Aptian-Albian, Albian-Cenomanian, three individual fault families within Late Cretaceous, and Paleocene. Furthermore, fault heave and displacement measurements were undertaken within the North Utrøst Ridge Fault Complex (NURFC) that exhibits prominent low-angle detachment faults of Cretaceous strata. The analysis demonstrated a progressively northwards increase of fault heave and displacement intensity from ~3 km in the south to ~7-8 km in the north of the study area, and a maximum stretching factor defined by fault geometry (βf) of ~1.7. These values when compared to the crustal stretching (i.e. >3) and thinning (0.7-0.9) factors required to achieve the observed extension on the >300-km-width extended NE Greenland-Vesterålen conjugate margins reveal an apparent extension discrepancy. Fault population analysis suggests that only ~14% of extension is seen from the faults on seismic profiles in the NURFC. Finally, a conceptual tectonic multiphase evolution model for lithospheric extension is proposed for the NE Greenland-Vesterålen conjugate margins, consisting of a lower and upper plate configuration. This model elaborates the more ductile mode of deformation evidenced by the Late Cretaceous-Paleocene low-angle detachment fault complexes on both conjugate margins and the asymmetry in crustal structure at the time of continental rupture at the Paleocene-Eocene transition. The study shows that the Vesterålen margin represents an essential area to study the tectono-stratigraphic evolution of the NE Atlantic margins.