Onshore–offshore potential field analysis of the Møre–Trøndelag Fault Complex and adjacent structures of Mid Norway

Abstract

The Møre–Trøndelag Fault Complex (MTFC) is one of the most prominent fault complexes of Scandinavia. It exerted a strong control on the development of offshore basins of Mid Norway and onshore topography. However, the relationships between the faults observed in the field onshore and those identified by means of seismic profiling offshore remain obscure. Regional gravity and aeromagnetic data are used to map regional-scale faults and, in particular, to delineate the main geophysical features related to the MTFC. The advantage of potential field data is to provide an almost continuous coverage and to tie bedrock mapping onshore to seismic interpretation offshore. In this paper, we apply potential field transformations to focus on the regional and deep-seated structures in order to extract new geological information. Also the tilt derivative technique (TDR) is applied to gravity and magnetic data with the aim of enhancing linear trends. The results indicate the possible onshore–offshore links of large scale structural elements like the MTFC and late-Caledonian detachments (e.g. Kollstraumen Detachment). The locations of different segments of the MTFC are detected and possible new faults/lineaments are depicted. Correlating petrophysical data with gravity and magnetic maps explains the influence of the MTFC on the deformation and mineralisation of bedrock along its strike. In addition, the structural pattern seen in the enhanced lineaments is diagnostic for the sinistral strike–slip movements that are known to have occurred in Devonian time along the MTFC. This confirms the important role of the MTFC in the tectonic setting and geological evolution of Mid Norway.