The current effort to move to more renewable energy sources and away from a petroleum based energy economy, ‘Net Zero’, places a renewed need for improving identification and characterization of mineral deposits in order to provide the materials required. Recent work, has demonstrated the benefit of larger aperture investigations of mineral systems for both determining the processes responsible for their emplacement as well as identifying indicative geophysical signatures associated with metal endowment. The central Norwegian Caledonides historically represent a zone of large mineral endowment, though; the large-scale structural history and process that formed the mineralization remain enigmatic. Formation and concentration of metals into economic mineral deposits requires a combination of processes operating at different scales. With the near surface mineral deposit being a small component of the larger mineral system which encompasses deep fluid sources and metals, an energy source for driving circulation pathways for the migration of enriched fluids, a depositional mechanism responsible for the formation of the deposit and a fluid outflow. The Norwegian mineral deposits lie within the allochthonous nappes, detached from the original Precambrian Svecokarelian and Sveconorwegian basement and having undergone tens to hundreds of km of lateral transport. Regional scale geophysical modelling of petrophysical properties has the ability to characterize and identify the structure and process occurring throughout the entire mineral system and determine indicative structures at mid-lower crustal depths indicative of economically viable near surface regions of metal endowment (i.e. the near surface mineral deposit). To determine the processes associated with formation of the Norwegian Caledonides and its associated mineral deposits a dense network of ~300 broadband magnetotelluric soundings covering the period range 10-3-103s have been collected over two field campaigns in 2022 and 2023 in the Trondelag area of central Norway. Phase tensor analysis indicates that the data set is 3D at all scales – we have modelled the MT data using a 3D approach (GoFEM) capable of incorporating the rugged topography of the survey area. Preliminary modeling results reveal lithospheric-scale structural controls associated with known near surface mineral deposits and processes related to the lateral transport from the underlying lower crustal source regions. As such, regional geophysical surveys offer both an economic and environmentally friendly approach to large-scale exploration efforts through identification of regional scale structural controls that are indicative of metal endowment.

Much of the Norwegian upper crust was shaped by Caledonian thrusting and post-orogenic extension. We investigate the electrical conductivity structure of the crust and associated thrusts and detachments using magnetotellurics to obtain a better understanding Paleozoic tectonics. New magnetotelluric data were collected over an area of c. 60 × 70 km that includes the Gudbrandsdalen Antiform and Atnsjø tectonic window in central Norway. The final 3D electrical conductivity model reveals a highly resistive crustal block, extending E–W along the Gudbrandsdalen Antiform and from the surface to several tens of kilometres depths, imaging the parautochthonous Precambrian basement. No major thrust or detachment has been mapped under the Atnsjø tectonic window, which is therefore considered to most likely represent autochthonous or parautochthonous Baltica basement. Several conductors are imaged along the edge of the magnetotelluric survey, which can be correlated with a major Caledonian thrust and structures in the Precambrian basement.

A recent aeromagnetic survey was carried out to refine our understanding of the structure and nature of the basement rocks beneath the Finnmark Platform (Norwegian Barents Sea). Magnetic depth source estimation and potential field models were used to explore the platform's basement architecture and evaluate the existence of Paleozoic basins. In the western part, magnetic fabrics suggest a continuation of Precambrian rocks into the adjacent platform. Further east, magnetic data reveal NW–SE-trending basement lineaments related to the Sørøya–Ingøya Shear Zone, formed during the Caledonian orogeny. Additionally, lower-frequency and discrete NNW–SSE lineaments may reflect the influence of older Precambrian structures. The Gjesvær Low, previously considered a post-orogenic basin, is now seen as a Caledonian backthrust system tied to the Sørøya–Ingøya Shear Zone. Both Precambrian and Caledonian inherited structures controlled and accommodated the development and segmentation of subsequent rift basins during the Paleozoic and Mesozoic. The NW–SE to WNW–ESE Precambrian trends guided early rift segmentation from the Devonian to Early Carboniferous, while Mesozoic rift border faults align with NE–SW to ENE–WSW-trending magnetic lineaments, largely interpreted as Caledonian in origin.

Norway is covered by high-resolution topographic data derived from airborne LiDAR (Light Detection and Ranging) acquisitions. These data enable highly accurate mapping of landforms, such as landslide scars and ravines, as well as detailed morphometric analyses of past landslides. Comprehensive mapping of landslide scars and ravines has been carried out in Norway during the last years, including around Romerike, Southern Norway. Here, the mapping dataset is integrated with information on subsurface conditions from geophysical and geotechnical data to develop a better understanding of how landslide occurrence, shape, and size relate to soil properties. This may improve landslide hazard assessments, future scenario predictions, and the understanding of regional landscape development.

The Nordland area in northern Norway is the seismically most active area on mainland Fennoscandia. It exhibits patterns of coastal extension, which contrasts with the first-order regional stress pattern that reflects compression aligned with the North Atlantic ridge push. The regional stress field has been considered to emanate from the interaction of ridge push and glacial isostatic adjustment; while the local stress pattern can be additionally influenced by gravitational, topographic stresses, as well as the flexural effects of erosion and sediment deposition. We employ finite element numerical models at a crustal scale to study the 3D stress field, using existing geometric constraints from previous geophysical studies. Internal body forces, induced by variations in density, topography or Moho depth, already yield significant deviatoric stresses. In the models tested, these can strongly influence the near-surface stress regime, in particular for the continental margin setting we are investigating. In addition, redistribution of rock mass, which occurred mainly under Pleistocene glaciation, can modify the stress field significantly on a semi-regional scale. We consider this process to be the main driver for the coastal extension, in particular in areas where erosion has been high.

We integrated high-resolution aeromagnetic data and 2D/3D seismic data from the Norwegian Southwestern Barents Sea. The main objective is to address the long-standing question on the role of pre-existing basement structures in controlling strain accommodation and extension in the Finnmark Platform and adjacent rift basins. The thorough qualitative analysis of the high-resolution magnetic data reveals fault geometries, regional kinematics, magmatism and inheritance of older Precambrian/Caledonian structures. Through the application of second order derivative filters and depth-to-magnetic-source modelling, the trends of the Caledonian metamorphic fabrics are identified and correlated with the structure of buried basement faults and shear zones also imaged at the same level of resolution on 2D/3D seismic data. The magnetic data reveal an unprecedented detail of the basement fabrics dominated by high-frequency NW-SE trending magnetic lineaments associated with the semi-regional Sørøya-Ingøya Shear Zone. The high-frequency magnetic lineaments are superimposed by lower frequency NNW-SSE trending magnetic lineaments that reflect the inheritance of older Precambrian structures. At the edge of the Tromsø Basin, the new magnetic data highlight sill intrusions also visible on seismic data. Fault geometries, regional kinematics, and spatial distribution of the magnetic sources suggest that old detachments and younger Mesozoic faults reactivated the basement fabrics found along the graben borders. Focusing of strain accommodation at the edge of the Hammerfest Basin is helped as well as modulated by the presence of back-thrusted Caledonian nappes interpreted on the Finnmark Platform. Offshore, surface ruptures associated with graben formation align with the dominant NNW-SSE trending magnetic lineaments defining steeper normal faults that are characterised by right-stepping segments along the southern flank of the Hammerfest Basin. Based on potential field models, we finally quantify the crustal architecture of the rift and platform system. At upper crustal level, we test the presence and significance of potential Palaeozoic basin preserved at the edge of the basement hinge-zones. Potential field modelling also highlights and quantifies several rift domains defined by moderate to extreme thinning of the crust (low-β stretched domain, necking, and high-β hyperextended regions). The development of the necking zone is clearly influenced by the existence of former first-order and multi-scale inherited basement features preserved in the Finnmark Platform.

Summary Quick-clay landslides are reported from different parts of the world, specially from Nordic countries, Canada, and Russia. Quick clay is mainly observed in marine clay areas. Various geophysical methods can help mapping of potential quick-clay deposits. NGU uses frequency-domain helicopter EM (HEM) and electrical resistivity tomography (ERT) to map potential quick-clay areas in Norway. Orkdal valley in Norway is characterized by thick deposits from the ice age and deglaciation period. In 2021 NGU, in collaboration with NVE, collected HEM, ERT and ground penetrating radar (GPR) data from Orkdal valley for quick-clay mapping. We present subsurface resistivity models obtained from full 3D inversion of HEM data and its comparison with ERT along one profile. There is a general good correlation between ERT and HEM data, and also with a geotechnical drilling profile from an earlier mapped quick-clay hazard zone.

SUMMARY The Nordland region, Northern Norway, situated in an intraplate continental setting, has the highest seismicity rate in mainland Norway. However, the exact cause of seismicity in this region is still debated. Better understanding of factors that influence the seismicity in Nordland can help increase knowledge of intraplate seismicity in general. Here, we address this problem with the aid of a new high-resolution 3-D VP and VP/VS ratio images of the crust in Nordland using seismic traveltime tomography. These images show the existence of a localized, 10–15 km Moho step that runs parallel to the coast. The north–south extent of this step coincides with the region that exhibits the highest rates of seismicity. Focal mechanisms of selected earthquakes computed in this study are dominated by normal and oblique-normal, indicating a coast-perpendicular extension. The coast-perpendicular extensional stress regime deviates from the regional compression imposed by the ridge push from the North Atlantic. This deviation is thought to stem from the additional interference with local flexural stress caused by sediment redistribution and glacial isostatic adjustment, and possibly exacerbated by gravitational potential energy stress associated with the Moho step. The deformation due to the extensional regime is localized on pre-existing faults and fractures along the coastline. The tomography result shows that two distinct seismic swarms occurred in the coastal area with low VP and variable VP/VS ratio anomalies, pointing towards fractured crust and possibly the presence of fluids. The existence of fluids here can change the differential stress and promote seismic rupture.

Modelling of stresses that influence glacially triggered faulting has progressed substantially in the last decades with more complex models and improved modelling techniques, incorporation of a variety of relevant processes, better constraints of ice-loading history, higher model resolution and 3D geometries. Some recent developments are collected in this section to portray the scope and variability of numerical modelling relevant to glacially triggered faulting. These range from modelling of the general in situ stress field to studies on the stress field induced by glacial loading and unloading.

The tectonic evolution of the former 'grey zone' between Russia and Norway has so far remained poorly constrained due to a lack of geophysical data. In 2014, the Geological Survey of Norway (NGU) carried out a new state-of-the-art aeromagnetic survey (BASAR-14) in the southern part of the new Norwegian offshore territory. The new BASAR-14 survey completes and extends the pre-existing aeromagnetic compilation and mapping of the Norwegian Barents Sea. We present this new magnetic dataset and its interpretation combined with gravity and seismic data. Caledonian and Timanian structures, highlighted by the new potential field data, dominate the basement patterns and have exerted a strong influence on the structure and development of the overlying basins and basement highs. Clearly associated with NW-SE-oriented Timanian trends, the Tiddlybanken Basin represents an atypical sag basin that developed at the southern edge of the Fedynsky High. Quantitative modelling along 2D seismic transects was also carried out to constrain the structural and basement composition of the study area. The predominant NE-SW Mesozoic trend of the Nordkapp Basin represents a major crustal hinge zone between the Finnmark Platform, poorly affected by major crustal deformation, and the Bjarmeland Platform where Late Palaeozoic lifting controlled the widespread accumulation of salt deposits in Late Carboniferous Early Permian time. The entire structure and segmentation of the Nordkapp Basin have been influenced by the inherited basement configuration highlighted by the new aeromagnetic data. At present, quite a few large diapiric salt domes along the Nordkapp and Tiddlybanken basins are relatively shallow, locally reaching the seabed and thus show a clear bathymetric and magnetic signature. Both the Nordkapp and the Tiddlybanken basins appear to lie at the edge of a peculiar thick and rigid crustal feature that coincides with a highly magnetic region. The abrupt termination of the eastern Nordkapp Basin at the edge of this magnetic domain suggests the presence of an old and thick Precambrian continental block. This magnetic and rigid tectonic buffer controlled the Late Palaeozoic pre-salt and Mesozoic post-salt tectonic development of the southeastern Barents Sea.

Magnetometry is one of the oldest geophysical methods and it is probably the first one which was applied to exploration. Significant technologically achievements in instrumentation and positioning made the application a fast and effective method to map geological and tectonic settings over large areas. Strong interaction of the Earth's magnetic field in the Arctic with external fields, mostly deriving from the sun, can disturb the magnetic signal from the crust and makes the acquisition at such high latitude extremely challenging. The Geological survey of Norway has more than 60 years of experience with airborne magnetic acquisition and together with TGS has acquired aeromagnetic data over Norway and almost the entire Norwegian shelf. The data contribute to characterize the underlying basement lithology on the Norwegian shelf, understanding better the tectonic processes of the sedimentary basins and the crustal heat flow. In the oceanic domain, seafloor spreading anomalies are predominant to identify the limit of the oceanic crust and allow plate reconstruction to better understand the opening of the North Atlantic.

Abstract The NE Atlantic region evolved through several rift episodes, leading to break-up in the Eocene that was associated with voluminous magmatism along the conjugate margins of East Greenland and NW Europe. Existing seismic refraction data provide good constraints on the overall tectonic development of the margins, despite data gaps at the NE Greenland shear margin and the southern Jan Mayen microcontinent. The maximum thickness of the initial oceanic crust is 40 km at the Greenland–Iceland–Faroe Ridge, but decreases with increasing distance to the Iceland plume. High-velocity lower crust interpreted as magmatic underplating or sill intrusions is observed along most margins but disappears north of the East Greenland Ridge and the Lofoten margin, with the exception of the Vestbakken Volcanic Province at the SW Barents Sea margin. South of the narrow Lofoten margin, the European side is characterized by wide margins. The opposite trend is seen in Greenland, with a wide margin in the NE and narrow margins elsewhere. The thin crust beneath the basins is generally underlain by rocks with velocities of >7 km s−1 interpreted as serpentinized mantle in the Porcupine and southern Rockall basins; while off Norway, alternative interpretations such as eclogite bodies and underplating are also discussed.

Abstract Seismic refraction data and results from receiver functions were used to compile the depth to the basement and Moho in the NE Atlantic Ocean. For interpolation between the unevenly spaced data points, the kriging technique was used. Free-air gravity data were used as constraints in the kriging process for the basement. That way, structures with little or no seismic coverage are still presented on the basement map, in particular the basins off East Greenland. The rift basins off NW Europe are mapped as a continuous zone with basement depths of between 5 and 15 km. Maximum basement depths off NE Greenland are 8 km, but these are probably underestimated. Plate reconstructions for Chron C24 (c. 54 Ma) suggest that the poorly known Ammassalik Basin off SE Greenland may correlate with the northern termination of the Hatton Basin at the conjugate margin. The most prominent feature on the Moho map is the Greenland–Iceland–Faroe Ridge, with Moho depths >28 km. Crustal thickness is compiled from the Moho and basement depths. The oceanic crust displays an increased thickness close to the volcanic margins affected by the Iceland plume.

Salt canopies are present in many of the worldwide large salt basins and are key players in the basins' structural evolution as well as in the development of associated hydrocarbon systems. This study employs 2D finite‐element models which incorporate the dynamical interaction of viscous salt and frictional‐plastic sediments in a gravity‐spreading system. We investigate the general emplacement of salt canopies that form in the centre of a large, autochthonous salt basin. This is motivated by the potential application to a mid‐basin canopy in the NW Gulf of Mexico (GoM) that developed in the late Eocene. Three different salt expulsion and canopy formation concepts that have been proposed in the salt‐tectonic literature for the GoM are tested. Two of these mechanisms require pre‐existing diapirs as precursory structures. We include their evolution in the models to assure a continuous, smooth evolution of the salt‐sediment system. The most efficient canopy formation takes place under the squeezed diapir mechanism. Here, shortening of a region containing pre‐existing diapirs is absorbed by the salt (the weakest part of the system), which is then expelled onto the seafloor. The expulsion rollover mechanism, which evacuates salt from beneath evolving rollover structures and expels it both laterally and to the surface, was not successfully captured by the numerical models. No rollover structures developed and only minor amounts of allochthonous salt emerged to the seafloor. The breached anticline mechanism requires substantial shortening of salt‐cored, pre‐weakened folds such that the salt breaches the anticlines and is expelled to the seafloor. The amount of shortening may be too large to occur in the central part of a salt basin, but may explain canopy evolution closer to the distal end of the allochthonous salt. When applying the different concepts to the northwestern GoM, none of the models adequately describes the entire system, yet the squeezed diapir mechanism captures most structural features of the Eocene paleocanopy. It is nevertheless possible that different mechanisms have acted in combination or sequentially in the northwestern GoM.

To understand the major structural features of the sedimentary cover and crystalline crust of the Lofoten-Vesteralen margin and the northern part of the Voring segment of the Mid-Norwegian continental margin, a lithosphere-scale 3-D structural model has been constructed. This model extends from the exposed crystalline rocks of the Fennoscandian Shield in the east to the Cenozoic oceanic domain of the Norwegian-Greenland Sea in the west, covering the Vestfjorden, Ribban, and Rost Basins and the northern parts of the Voring Basin and Trondelag Platform. All available published and/or released data have been used to set the initial 3-D model which has been validated by means of 3-D density forward modeling to obtain a gravity-consistent 3-D structural/density model. Results from the 3-D density modeling reveal that relatively thick sedimentary rocks are present in the distal Rost Basin below the lava flows. The presence of a low-density more than 20 km thick granitic body has been modeled within the middle-upper crystalline crust beneath the eastern part of the Vestfjorden Basin and the adjacent mainland. Moreover, the results of the 3-D density modeling indicate the presence of an atypical low-density lithospheric mantle beneath a large part of the Lofoten-Vesteralen margin which is required to fit the regional component of the modeled gravity with the observed one. The pronounced crustal feature within the model area is the Bivrost Lineament that appears to be the deeply seated lithosphere-scale boundary that delineates clearly the Lofoten-Vesteralen segment from the Voring margin showing contrasting densities and crustal thicknesses.