New insights into the late Mesozoic-Cenozoic tectono-stratigraphic evolution of the northern Lofoten-Vesterålen margin, offshore Norway

Abstract

2D multi-channel seismic profiles and a 3D seismic survey were utilised together with potential field and available well data to study the late Mesozoic-Cenozoic tectono-stratigraphic evolution of the northern Lofoten-Vesterålen margin, offshore northern Norway. The analysis resulted in an updated structural and stratigraphic framework, together with new and better refined structural elements. Distinct along-margin basin segmentation is evident and is imposed by 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. In addition, compressional deformation features are observed and related to volcanic build-up and doming of Cenozoic successions. Large parts of the study area are dominated by a prominent low-angle detachment fault complex informally named North Utrøst Ridge Fault Complex, and the study of the fault complex with the 3D seismic survey has brought forward new details into the composite Late Cretaceous-Paleocene rifting. A major component of the latter is low-angle detachment faulting that is also observed on the conjugate NE Greenland margin. This is a key evidence of conjugate, more ductile, mode of deformation at intermediate-to-deep crustal levels that consisted of lower- and upper-plate configurations and reflects a multiphase tectonic evolution. The study shows that the northern Lofoten-Vesterålen margin represents an essential area to study the tectono-stratigraphic evolution of the NE Atlantic margins.