Integrated interpretation of seismic and potential field data on the Frøya High, Mid Norway

Abstract

The mid-Norwegian continental margin has been tectonically active from the Caledonian Orogeny. The main tectonic phases happened during Jurassic-Cretaceous and Cretaceous-Cenozoic time. This thesis will present interpretations of the tectonic development and crustal architecture in the Møre Basin and surrounding platform domain. The main focus of this study is the Frøya High, a basement high structure separating the deep Cretaceous Møre sag-basin in the west from the Froan Basin to the east. The basement high and adjacent structures have been subject to several interpretations, in particular the origin and composition of the crust in the area is still disputed. From analysis and interpretation of gravity and magnetic data, a combined ophiolite and intrusion with high-density lower crust is suggested for the Frøya High by this thesis. Some previous works suggest evidence of reactivation of the bounding Klakk Fault Complex in the Cretaceous. Seismic and potential field investigation in this thesis does not find evidence to support the reactivation. The majority of the structures on the Mid-Norwegian margin are defined at the base Cretaceous level, and it has been discussed if the BCU forms the transition from syn- to post-rift. This study investigates this through seismic, potential field and well data, where it is concluded that the tectonic activity in the basin terminates at the Jurassic-Cretaceous transition. Further, the interpretation of regional potential field data reveals new information and understanding of the Mid-Norwegian framework. Typical crustal structure of the area is presented as a result from potential field modeling integrated with seismic and petrophysical data.

Keywords: 2D and 3D seismic, potential field, mid-Norwegian continental margin, Frøya High, structural analysis.