Asbjørn Johan Breivik

• Aarseth, Iselin; Minakov, Alexander; Shulgin, Alexey; Hauge, Brede Engum; Breivik, Asbjørn & Faleide, Jan Inge [Vis alle 8 forfattere av denne artikkelen] (2025). The Storfjorden earthquake sequence: role of inherited crustal heterogeneity. Geophysical Journal International. ISSN 0956-540X. 243(3). doi: 10.1093/gji/ggaf386. Fulltekst i vitenarkiv Vis sammendrag

  A strong earthquake sequence in Storfjorden, south of Svalbard, was initiated by an Mw 6.1 event on 2008 February 21. Earthquake distribution and fault plane solutions indicate that seismic activity is controlled by unmapped NE-SW striking oblique-normal faults, contrasting with the major N-S oriented faults mapped onshore Svalbard. We present a geophysical model derived from an ocean bottom seismometer profile crossing the seismogenic zone to identify structures in the crust and uppermost mantle that potentially control the earthquake source mechanism. Traveltime forward modelling using ray tracing, combined with traveltime tomography and gravity-magnetic modelling, reveal distinct crustal domains across the earthquake region. Crystalline crustal P-wave velocities range from 6.1 to 6.7 km s−1 at the Moho depth in the eastern section. The western profile section exhibits a higher Vp velocity lower crust (6.6–7.0 km s−1) with Vp/Vs ratios of 1.75–1.8 and high density (∼3100 kg m−3). Basement depth reaches 8 km in the west, forming a sedimentary basin, and shallows eastward. The Moho remains relatively flat at 29–32 km depth throughout the profile. The N–S oriented Caledonian suture, identified from deep seismic and potential field data, traverses the Storfjorden earthquake zone. The lithological contacts within the suture zone, inferred from the new OBS data, may facilitate seismic failure oblique to the N–S oriented structure, following the regional stress field.

• Tan, Pingchuan; Breivik, Asbjørn; Ding, Weiwei; Zhang, Tao; Niu, Xiongwei & Li, Jiabiao (2024). Unexpectedly High Magma Productivity Inferred From Crustal Roughness and Residual Bathymetry on the Eastern Part of the Ultra-Slow Spreading Gakkel Ridge Since ∼45 Ma, Eurasian Basin, Arctic Ocean. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 129(6). doi: 10.1029/2023JB028470. Fulltekst i vitenarkiv Vis sammendrag

  The Gakkel Ridge in the Eurasian Basin has the slowest seafloor spreading worldwide. The western Gakkel Ridge (3°W–85°E; 14–11 mm/a) alternate between magmatic and sparsely magmatic zones, while the eastern Gakkel Ridge (85–126°E; 11–6 mm/a) appears to be dominated by magmatic zones despite ultraslow spreading. Little is known about the seafloor spreading conditions in the past along the entire ridge. Here, we exploit the residual bathymetry and basement roughness to assess the crustal accretion process of the Gakkel Ridge over time using 23 published regional multichannel seismic reflection profiles. Full seafloor spreading rates were faster (20–24 mm/a) up to ∼45 Ma, and residual bathymetry for the older crust is deeper than the world average in the entire Eurasian Basin. There is a sharp transition to 300–400 m shallower residual bathymetry for seafloor <45 Ma in the eastern Eurasian Basin. The crustal roughness versus spreading rate of the western Eurasian Basin is on the global trend, while that of the eastern is significantly below. Both low roughness and shallow residual bathymetry of the eastern Eurasian Basin is close to that of oceanic crust for spreading rates above 30 mm/a, demonstrating increased magmatic production of the eastern Gakkel Ridge since ∼45 Ma. A recent mantle tomography model predicts partial melting in the upper mantle based on the low Vs anomaly underneath. The sedimentary pattern toward the Lomonosov Ridge indicates that this hot mantle anomaly started to cause dynamic uplift of the area at ∼45 Ma.

• Tan, Pingchuan & Breivik, Asbjørn (2022). Formation of the Igneous Logi Ridge, NE Atlantic. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 127(3). doi: 10.1029/2021JB023891. Fulltekst i vitenarkiv Vis sammendrag

  The igneous Logi Ridge is located in the NE Atlantic north of the West Jan Mayen Fracture Zone on oceanic crust. The origin of the ridge may relate to the increased influence of the Iceland plume in the Oligocene though the exact mechanism is uncertain. We estimate the igneous volume and magma production rate of the ridge from 10 transects, comprising a refraction profile, six reflection profiles, and three bathymetric profiles. The refraction profile shows up to 12 km crustal thickness of the ridge, and the forward gravity modeling and/or isostatic balancing shows that this is characteristic for most of the ridges. A 3D volume model was created by interpolating between profiles and subtracted the similarly made regional crustal thickness (5–7 km), which gives an excess magma volume of (1.7 ± 0.6) × 1013 m3. The admittance function between bathymetry and gravity indicates an elastic plate thickness of 3–5 km during the main ridge formation. This is consistent with the ridge being built on oceanic crust from Oligocene to earliest Miocene, indicating a main magmatic phase of ∼5 Ma duration, which gives a magma production rate of 0.07–0.15 m3/s, comparable to the Louisville Seamount Chain (LSC). However, the lower crustal velocities of the refraction profile differ from that of the Louisville Guyot in the LSC, suggesting that the melting event was not mainly caused by high mantle temperature, instead it may have been caused in part by the enriched mantle presently seen at the northern end of the Kolbeinsey Ridge to the south.

• Shulgin, Alexey A; Faleide, Jan Inge; Mjelde, Rolf; Breivik, Asbjørn Johan & Huismans, Ritske Sipke (2021). Crustal domains in the Western Barents Sea. Geophysical Journal International. ISSN 0956-540X. 221(3), s. 2155–2169. doi: 10.1093/GJI/GGAA112. Fulltekst i vitenarkiv Vis sammendrag

  The crustal architecture of the Barents Sea is still enigmatic due to complex evolution during the Timanian and Caledonian orogeny events, further complicated by several rifting episodes. In this study we present the new results on the crustal structure of the Caledonian–Timanian transition zone in the western Barents. We extend the work of Aarseth et al. (2017), by utilizing the seismic tomography approach to model Vp, Vs and Vp/Vs ratio, combined with the reprocessed seismic reflection line, and further complemented with gravity modelling. Based on our models we document in 3-D the position of the Caledonian nappes in the western Barents Sea. We find that the Caledonian domain is characterized by high crustal reflectivity, caused by strong deformation and/or emplacement of mafic intrusions within the crystalline crust. The Timanian domain shows semi-transparent crust with little internal reflectivity, suggesting less deformation. We find, that the eastern branch of the earlier proposed Caledonian suture, cannot be associated with the Caledonian event, but can rather be a relict from the Timanian terrane assemblance, marking one of the crustal microblocks. This crustal block may have an E–W striking southern boundary, along which the Caledonian nappes were offset. A high-velocity/density crustal body, adjacent to the Caledonian–Timanian contact zone, is interpreted as a zone of metamorphosed rocks based on the comparison with global compilations. The orientation of this body correlates with regional gravity maxima zone. Two scenarios for the origin of the body are proposed: mafic emplacement during the Timanian assembly, or massive mafic intrusions associated with the Devonian extension.

• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst & Murai, Yoshio (2020). Crustal structure and erosion of the Lofoten/Vesterålen shelf, northern Norwegian margin. Tectonophysics. ISSN 0040-1951. 776. doi: 10.1016/j.tecto.2020.228318. Fulltekst i vitenarkiv Vis sammendrag

  The Norwegian continental shelf has been through several rift phases since the Caledonian orogeny. Early Cretaceous rifting created the largest sedimentary basins, and Early Cenozoic continental breakup between East Greenland and Europe affected the continental shelf to various degrees. The Lofoten/Vesterålen shelf is located off Northern Norway, bordering the epicontinental Barents Sea to the northeast, and the deep-water Lofoten Basin to the west. An ocean bottom seismometer/hydrophone (OBS) survey was conducted over the shelf and margin areas in 2003 to constrain crustal structure and margin development. This study presents Profile 8-03, located between the islands of Lofoten/Vesterålen and the shelf edge. The wide-angle seismic data were modeled using forward/inverse raytracing to build a crustal velocity-depth transect. Gravity modeling was used to resolve an ambiguity in seismic Moho identification in the southwestern part. Results show a crustal thickness of ~31 km, significantly thicker than what a vintage land station based study suggested. Profile 8-03 and other OBS profiles to the southwest show high sedimentary velocities at or near the seafloor, increasing rapidly with depth. Sedimentary velocities were compared to the velocity-depth function derived from an OBS profile at the Barents Sea margin, tied to a coincident well log, where there is little erosion. Results from this profile and the crossing Profile 6-03 (Breivik et al. 2017) indicate three major erosion episodes; Late Triassic-Early Jurassic, tentatively mid-Cretaceous, Late Cretaceous–early Cenozoic, and a minor late glacial erosion episode off Vesterålen.

• Tan, Pingchuan; Breivik, Asbjørn Johan & Mjelde, Rolf (2019). Dynamic topography development north of Iceland from subaerial exposure of the igneous Logi Ridge, NE Atlantic. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 124(11), s. 10799–10822. doi: 10.1029/2019JB017603. Fulltekst i vitenarkiv Vis sammendrag

  The Logi Ridge, located north of the West Jan Mayen Fracture Zone, is E-W oriented and 140-150 km long. The seafloor surrounding the Logi Ridge is ~0.65 km shallower than the conjugate seafloor east of the Mohn’s Ridge, attributed to asymmetry in the regional NE Atlantic dynamic uplift. Eight reflection seismic lines across the Logi Ridge constrain its development. Both the western and eastern parts have flat tops, indicating erosion at sea-level. Three different basement types surrounding the Logi Ridge are observed: rough basement represents abyssal hills original, or reactivated by later magmatic/tectonic events; smooth basement caused by basalt flows overprinting early sediments; irregular basement formed by later basalt flows and intrusions. The surrounding sediments have two distinct units, where the unit boundary is Middle Miocene (12-14 Ma). Mass transport from the Logi Ridge appears episodically throughout Late Oligocene to Middle Miocene, when development ends. The end of erosion age can also be estimated from seamount height, or present top seamount depth. In the west there is agreement with the age constrained by the sedimentation, proving little dynamic topography change. In the east, discrepancies between the methods are explained by 0.15-0.3 km dynamic uplift after submergence. Hence, most of the regional dynamic uplift occurred before the end of the Logi Ridge development in the Middle Miocene, suggesting a causative relationship. Minor recent magmatic growth and seafloor uplift over a ~100 km wide zone south-east of the Logi Ridge may be tied to the younger dynamic uplift in the east.

• Tan, Pingchuan; Sippel, Judith; Breivik, Asbjørn Johan; Meessen, Chrisitian & Scheck-Wenderoth, Magdalena (2018). Lithospheric Control on Asthenospheric Flow From the Iceland Plume: 3-D Density Modeling of the Jan Mayen-East Greenland Region, NE Atlantic. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 123(10), s. 9223–9248. doi: 10.1029/2018JB015634. Fulltekst i vitenarkiv Vis sammendrag

  The density structure of the oceanic lithosphere north of Iceland is key for understanding the effects of the Iceland plume on the greater Jan Mayen-East Greenland Region. We obtain the 3-D density structure of the sediments and the crust from regional reflection and refraction seismic lines. The temperature and related density structures of the mantle between 50 and 250 km are derived from a shear wave velocity (Vs) tomography model. To assess the density between the Moho and 50-km depth, we combine forward and inverse 3-D gravity modeling. Beneath the Middle Kolbeinsey Ridge (MKR) region, a deep, broad negative mantle density anomaly occurs under the Kolbeinsey Ridge. It is overlain by a narrower uppermost mantle NE-SW elongated negative density anomaly, which is increasingly displaced eastward of the spreading axis northward. It crosses the West Jan Mayen Fracture Zone and becomes weaker approaching the Mohn’s spreading ridge. The effect of this anomaly is consistent with significantly shallower basement on the eastern side of the MKR. We interpret this as the result of thermal erosion of the lithosphere by hot asthenospheric flow out from the Iceland plume, possibly the main driver for several eastward jumps of the MKR during the last 5.5 Ma. The cause for the deviation of the flow may be that the West Jan Mayen Fracture Zone is easier to cross in a region where the difference in lithospheric thickness is small. That implies that the bottom lithospheric topography exerts a regional but not local influence on upper asthenospheric flow.

• Aarseth, Iselin; Mjelde, Rolf; Breivik, Asbjørn Johan; Minakov, Alexander; Faleide, Jan Inge & Flueh, Ernst R. [Vis alle 7 forfattere av denne artikkelen] (2017). Crustal structure and evolution of the Arctic Caledonides: Results fromcontrolled-source seismology. Tectonophysics. ISSN 0040-1951. 718, s. 9–24. doi: 10.1016/j.tecto.2017.04.022. Fulltekst i vitenarkiv Vis sammendrag

  The continuation of the Caledonides into the Barents Sea has long been a subject of discussion, and two major orientations of the Caledonian deformation fronts have been suggested: NNW-SSE striking and NE-SW striking. A regional NW-SE oriented ocean bottom seismic profile across the western Barents Sea was acquired in 2014. In this paper we map the crust and upper mantle structure along this profile in order to discriminate between different interpretations of Caledonian structural trends and orientation of rift basins in the western Barents Sea. Modeling of P-wave travel times has been done using a ray-tracing method, and combined with gravity modeling. The results show high P-wave velocities (4 km/s) close to the seafloor, as well as localized sub-horizontal high velocity zones (6.0 km/s and 6.9 km/s) at shallow depths which are interpreted as magmatic sills. Refractions from the top of the crystalline basement together with reflections from the Moho give basement velocities from 6.0 km/s at the top to 6.7 km/s at the base of the crust. P-wave travel time modeling of the OBS profile indicate an eastwards increase in velocities from 6.4 km/s to 6.7 km/s at the base of the crystalline crust, and the western part of the profile is characterized by a higher seismic reflectivity than the eastern part. This change in seismic character is consistent with observations from vintage reflection seismic data and is interpreted as a Caledonian suture extending through the Barents Sea, separating Barentsia and Baltica. Local deepening of Moho (from 27 km to 33 km depth) creates “root structures” that can be linked to the Caledonian compressional deformation or a suture zone imprinted in the lower crust. Our model supports a separate NE-SW Caledonian trend extending into the central Barents Sea, branching off from the northerly trending Svalbard Caledonides, implying the existence of Barentsia as an independent microcontinent between Laurentia and Baltica.

• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst R. & Murai, Yoshio (2017). A new tectono-magmatic model for the Lofoten/Vesterålen Margin at the outer limit of the Iceland Plume influence. Tectonophysics. ISSN 0040-1951. 718, s. 25–44. doi: 10.1016/j.tecto.2017.07.002. Fulltekst i vitenarkiv Vis sammendrag

  The Early Eocene continental breakup was magma-rich and formed part of the North Atlantic Igneous Province. Extrusive and intrusive magmatism was abundant on the continental side, and a thick oceanic crust was produced up to a few m.y. after breakup. However, the extensive magmatism at the Vøring Plateau off mid-Norway died down rapidly northeastwards towards the Lofoten/Vesterålen Margin. In 2003 an Ocean Bottom Seismometer profile was collected from mainland Norway, across Lofoten, and into the deep ocean. Forward/inverse velocity modeling by raytracing reveals a continental margin transitional between magma-rich and magma-poor rifting. For the first time a distinct lower-crustal body typical for volcanic margins has been identified at this outer margin segment, up to 3.5 km thick and ∼50 km wide. On the other hand, expected extrusive magmatism could not be clearly identified here. Strong reflections earlier interpreted as the top of extensive lavas may at least partly represent high-velocity sediments derived from the shelf, and/or fault surfaces. Early post-breakup oceanic crust is moderately thickened (∼8 km), but is reduced to 6 km after 1 m.y. The adjacent continental crystalline crust is extended down to a minimum of 4.5 km thickness. Early plate spreading rates derived from the Norway Basin and the northern Vøring Plateau were used to calculate synthetic magnetic seafloor anomalies, and compared to our ship magnetic profile. It appears that continental breakup took place at ∼53.1 Ma, ∼1 m.y. later than on the Vøring Plateau, consistent with late strong crustal extension. The low interaction between extension and magmatism indicates that mantle plume material was not present at the Lofoten Margin during initial rifting, and that the observed excess magmatism was created by late lateral transport from a nearby pool of plume material into the lithospheric rift zone at breakup time.

• Tan, Pingchuan; Breivik, Asbjørn Johan; Trønnes, Reidar G; Mjelde, Rolf; Azuma, Ryosuke & Eide, Sigurd (2017). Crustal structure and origin of the Eggvin Bank west of Jan Mayen, NE Atlantic. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 122(1), s. 43–62. doi: 10.1002/2016JB013495. Fulltekst i vitenarkiv Vis sammendrag

  The Eggvin Bank, located between the Jan Mayen Island and Greenland, is an unusually shallow area containing several submarine volcanic peaks, confined by two transforms on the Northern Kolbeinsey Ridge (NKR). We represent P and S wave velocity models for the Eggvin Bank based on an Ocean Bottom Seismometer profile collected in 2011, showing igneous crustal thickness variations from 8 km to 13 km. A 2–5 km increase is associated with two separate 20–30 km wide segments under the main seamounts. The oceanic crust has three layers: upper crust (L2A: 2.8–4.8 km/s), middle crust (L2B: 5.5–6.5 km/s), and lower crust (L3: 6.7–7.35 km/s). Both the thick layer 2(A/B) and the high ratio of layer 2(A/B) thickness to total crustal thickness indicate that secondary, intraplate magmatism built the seamounts of the Eggvin Bank. The seamount in the north where the crust is thickest has a flat top indicating subaerial exposure but is deeper than those with rounded tops in the south and is therefore probably older. Comparing lower crustal seismic velocity with crustal thickness also indicates that the degree of mantle melting may be higher in the north than in the south. An enriched mantle source presently feeds the NKR magmatism and probably influenced the Eggvin Bank development also at earlier times. To what extent the Eggvin Bank has been influenced by the Iceland plume is uncertain, both an enriched mantle component and elevated mantle temperature may have played a role at different times and locations.

• Howell, Samuel Matthew; Ito, Garrett; Breivik, Asbjørn Johan; Rai, Abhishek Kumar; Mjelde, Rolf & Hanan, Barry [Vis alle 8 forfattere av denne artikkelen] (2014). The origin of the asymmetry in the Iceland hotspot along the Mid-Atlantic Ridge from continental breakup to present-day. Earth and Planetary Science Letters. ISSN 0012-821X. 392, s. 143–153. doi: 10.1016/j.epsl.2014.02.020. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst R. & Murai, Yoshio (2014). Magmatic development of the outer Vøring margin from seismic data. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 119(9), s. 6733–6755. doi: 10.1002/2014JB011040. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Mjelde, Rolf; Faleide, Jan Inge & Murai, Yoshio (2012). The eastern Jan Mayen microcontinent volcanic margin. Geophysical Journal International. ISSN 0956-540X. 188(3), s. 798–818. doi: 10.1111/j.1365-246X.2011.05307.x. Fulltekst i vitenarkiv Vis sammendrag

  The Jan Mayen microcontinent (JMMC) in the NE Atlantic was created through two Cenozoic rift episodes. Originally part of East Greenland, the JMMC rifted from NW Europe during the Early Eocene under extensive magmatism. The eastern margin is conjugate to the Møre–Faeroes volcanic margin. The western JMMC margin underwent prolonged extension before it finally separated from East Greenland during the Late Oligocene. Here we present the modelling by forward/inverse ray tracing of two wide-angle seismic profiles acquired using Ocean Bottom Seismometers, across the northern and the southern JMMC. Early Eocene breakup magmatism at the eastern JMMC produced an igneous thickness of 7–9 km in the north, and 12–14 km in the south. While the continent is clear in the north, the southern JMMC appears to be affected by later Icelandic magmatism. Reduced seismic velocity and increased crustal thickness are compatible with continental crust adjacent to the volcanic margin in the south, but the continental presence towards the Iceland shelf is less clear. Our magnetic track off the southern JMMC gives seafloor spreading rates comparable to that of the conjugate Møre Margin. Transition to ultraslow seafloor spreading occurs at ∼43 Ma, indicating onset of major deformation of the JMMC. Calculating the igneous thickness—mean VP relationship at the eastern volcanic margin gives the typical positive correlation seen elsewhere on the NE Atlantic margins. The results indicate temperature driven breakup magmatism under passive mantle upwelling, with a maximum mantle temperature anomaly of ∼50 ◦C in the north and 90–150 ◦C in the south.

• Breivik, Asbjørn Johan; Mjelde, Rolf; Raum, Thomas Johan; Faleide, Jan Inge; Murai, Yoshio & Flueh, Ernst R. (2010). Crustal structure beneath the Trondelag Platform and adjacent areas of the mid-Norwegian margin, as derived from wide-angle seismic and potential field data. Norsk Geologisk Tidsskrift. ISSN 0029-196X. 90(4), s. 141–161. Fulltekst i vitenarkiv
• Bruvoll, Vibeke; Breivik, Asbjørn Johan; Mjelde, Rolf & Pedersen, Rolf-Birger (2009). Burial of the Mohn-Knipovich seafloor spreading ridge by the Bear Island Fan: Time constraints on tectonic evolution from seismic stratigraphy. Tectonics. ISSN 0278-7407. 28. doi: 10.1029/2008TC002396. Fulltekst i vitenarkiv
• Breivik, Asbjørn; Faleide, Jan Inge; Mjelde, Rolf & Flueh, Ernst R. (2009). Magma productivity and early seafloor spreading rate correlation on the northern Vøring Margin, Norway — Constraints on mantle melting. Tectonophysics. ISSN 0040-1951. 468(1-4), s. 206–223. doi: 10.1016/j.tecto.2008.09.020. Fulltekst i vitenarkiv
• Mjelde, Rolf; Faleide, Jan Inge; Breivik, Asbjørn Johan & Raum, Thomas Johan (2009). Lower crustal composition and crustal lineaments on the Vøring Margin, NE Atlantic: A review. Tectonophysics. ISSN 0040-1951. 472(1-4), s. 183–193. doi: 10.1016/j.tecto.2008.04.018. Fulltekst i vitenarkiv
• Mjelde, Rolf; Breivik, Asbjørn; Raum, Thomas Johan; Mittelstaedt, Eric; Ito, Garrett & Faleide, Jan Inge (2008). Magmatic and tectonic evolution of the North Atlantic. Journal of the Geological Society. ISSN 0016-7649. 165(1), s. 31–42. doi: 10.1144/0016-76492007-018. Fulltekst i vitenarkiv
• Mjelde, Rolf; Breivik, Asbjørn Johan; Raum, Thomas; Mittelstaedt, E; Ito, G & Faleide, Jan Inge (2008). Magmatic and tectonic evolution of the North Atlantic. Journal of the Geological Society. ISSN 0016-7649. 165, s. 31–42. Fulltekst i vitenarkiv
• Mjelde, Rolf; Raum, Thomas Johan; Breivik, Asbjørn & Faleide, Jan Inge (2008). Crustal transect across the North Atlantic. Marine Geophysical Research. ISSN 0025-3235. 29(2), s. 73–87. doi: 10.1007/s11001-008-9046-9. Fulltekst i vitenarkiv
• Breivik, Asbjørn; Faleide, Jan Inge & Mjelde, Rolf (2008). Neogene magmatism northeast of the Aegir and Kolbeinsey ridges, NE Atlantic: Spreading ridge-mantle plume interaction? Geochemistry Geophysics Geosystems. 9. doi: 10.1029/2007GC001750. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, R; Ritzmann, Oliver & Engen, Øyvind [Vis alle 8 forfattere av denne artikkelen] (2008). Structure and evolution of the continental margin off Norway and Barents Sea. Episodes. ISSN 0705-3797. 31. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Mjelde, Rolf; Faleide, Jan Inge & Murai, Yoshio (2006). Rates of continental breakup magmatism and seafloor spreading in the Norway Basin-Iceland plume interaction. Journal of Geophysical Research (JGR). ISSN 0148-0227. 111. doi: 10.1029/2005JB004004. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst R. & Murai, Yoshio (2019). Wide angle seismic data constraints on crustal structure and erosion of the northernmost Norwegian shelf. Fulltekst i vitenarkiv Vis sammendrag

  The Norwegian continental shelf has been through several rift phases since the Caledonian orogeny. Early Cretaceous rifting created the largest sedimentary basins, and Early Cenozoic continental breakup between East Greenland and Europe affected the continental shelf to various degrees. The Lofoten/Vesterålen shelf is located off Northern Norway, bordering the epicontinental Barents Sea to the northeast, and the oceanic Lofoten Basin to the west. An ocean bottom seismometer (OBS) survey was conducted over the area in 2003. This study documents Profile 8-03, located between the outer islands and the shelf edge. The wide-angle seismic data were modeled using raytracing to build a crustal velocity-depth transect. Gravity modeling could resolve an ambiguity in seismic Moho identification in the south. Results show a crustal thickness of 30-31 km, thicker and thus less affected by breakup tectonism than previously believed. The results of the new survey shows that older nearby refraction profiles may be too short to constrain Moho depth in the area. Profile 8-03 and other OBS profiles to the southwest show high sedimentary velocities at or near the seafloor, suggesting greater burial in the past. Velocities from the current profile and from a previously published crossing profile of the same survey were compared to the velocity-depth function derived from an OBS profile at the Barents Sea margin, tied to a coincident well log, where there is little erosion. Results indicate three major erosion episodes; Late Triassic-Early Jurassic, tentatively mid-Cretaceous, Late Cretaceous-early Cenozoic breakup-related, and a minor late glacial erosion episode off Vesterålen.

• Breivik, Asbjørn Johan; Tan, Pingchuan & Mjelde, Rolf (2019). Dynamic topography development north of Iceland from subaerial exposure and erosion of the igneous Logi Ridge. Fulltekst i vitenarkiv Vis sammendrag

  The Logi Ridge, located north of the West Jan Mayen Fracture Zone, is E-W oriented and 140-150 km long, terminating in an isolated seamount in the east. The seafloor surrounding the Logi Ridge is ~0.65 km shallower than conjugate seafloor east of the Mohn's Ridge, which has been attributed to dynamic uplift due to asthenospheric flow. Eight reflection seismic lines across the Logi Ridge constrain its development. Both the western and eastern parts have flat tops, indicating erosion at sea-level. Three different basement types surrounding the Logi Ridge are observed: rough basement represents abyssal hills; smooth basement caused by basalt flows overprinting early sediments; and irregular basement formed by basalt flows and intrusions. The surrounding sediments have two distinct units, where the age of the unit boundary is Middle Miocene (~12 Ma). Lava flows and erosion products from the Logi Ridge appears episodically in the lower unit throughout Late Oligocene to Middle Miocene. Ridge development may have started just after the Traill Ø intrusions were emplaced onshore Greenland. No erosion products are seen in the upper unit, proving Middle Miocene submergence. The end of erosion age can also be estimated from seamount height, or present top seamount depth, using the age-dependent oceanic floor subsidence. The two methods have different sensitivity to parameters, which constrains uncertainty when compared. In the west there is good agreement with the age constrained by the sedimentation, proving little dynamic topography change. In the east, discrepancies between the methods are best explained by 0.15-0.3 km increase of dynamic uplift after submergence. Hence, most of the regional dynamic uplift occurred before the end of the Logi Ridge development in the Middle Miocene, suggesting a causative relationship. Minor recent magmatic growth and seafloor uplift over a ~100 km zone southeast of the Logi Ridge may be tied to the younger dynamic uplift in the east.

• Breivik, Asbjørn Johan (2018). Along-Margin Variability in Breakup Magmatism, NE Atlantic. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Tan, Pingchuan & Mjelde, Rolf (2018). Development of the Igneous Logi Ridge, NE Atlantic, From Seismic Reflection Data. Fulltekst i vitenarkiv
• Tan, Pingchuan; Breivik, Asbjørn Johan & Mjelde, Rolf (2018). Development of the igneous Logi Ridge and surrounding sedimentation, NE Atlantic, from seismic reflection data. Fulltekst i vitenarkiv
• Gibbons, Steven John; Maupin, Valerie; Kolstad, Christian; Kværna, Tormod & Breivik, Asbjørn Johan (2018). Improved location estimates for seismicity along the northern North Atlantic Ridge. Fulltekst i vitenarkiv
• Tan, Pingchuan; Sippel, Judith; Breivik, Asbjørn Johan; Scheck-Wenderoth, Magdalena & Meessen, Christian (2017). 3D Density Structure of Oceanic Lithosphere Affected by A Plume: A Case Study from the Greater Jan Mayen-East Greenland Region (NE Atlantic). Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst R. & Murai, Yoshio (2017). The Transition from Volcanic to Rift Dominated Crustal Breakup – From the Vøring Plateau to the Lofoten Margin, Norway. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst R. & Murai, Yoshio (2017). Origin of the Vøring Plateau, offshore Norway – interplay between timing of rifting and emplacement of plume material. Fulltekst i vitenarkiv
• Mjelde, Rolf; Breivik, Asbjørn Johan; Minakov, Alexander; Huismans, Ritske & Faleide, Jan Inge (2016). Barents Sea Crustal and Upper Mantle Structure from Deep Seismic and Potential Field Data. Fulltekst i vitenarkiv
• Aarseth, Iselin; Mjelde, Rolf; Breivik, Asbjørn Johan; Minakov, Alexander; Huismans, Ritske & Faleide, Jan Inge (2016). Barents Sea Crustal and Upper Mantle Structure from Deep Seismic and Potential Field Data. Fulltekst i vitenarkiv
• Aarseth, Iselin; Mjelde, Rolf; Breivik, Asbjørn Johan; Huismans, Ritske & Faleide, Jan Inge (2016). Barents Sea Paleozoic basement and basin configurations: Crustal structure from deep seismic and potential field data. Fulltekst i vitenarkiv
• Aarseth, Iselin; Mjelde, Rolf; Breivik, Asbjørn Johan; Huismans, Ritske & Faleide, Jan Inge (2016). Barents Sea Paleozoic basement and basin configurations: Crustal structure from deep seismic and potential field data. Fulltekst i vitenarkiv
• Tan, Pingchuan; Sippel, Judith; Breivik, Asbjørn Johan; Scheck-Wenderoth, Magdalena & Meeßen, Christian (2016). Crustal and mantle structure of the greater Jan MayenEast Greenland region (NE Atlantic) from combined 3D structural, Swave velocity, and gravity modeling. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Mahajan, Aatisha; Gabrielsen, Roy Helge; Breivik, Asbjørn Johan; Planke, Sverre & Myklebust, Reidun (2015). Basement and Late Paleozoic basin configurations in the western and central Barents Sea. Fulltekst i vitenarkiv
• Tan, Pingchuan; Breivik, Asbjørn Johan; Mjelde, Rolf & Azuma, Ryosuke (2015). Constraining formation of the Eggvin Bank (West of Jan Mayen, N. Atlantic) from OBS data. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Murai, Yoshio & Flueh, Ernst R. (2014). Breakup Style and Magmatic Underplating West of the Lofoten Islands, Norway, Based on OBS Data. Fulltekst i vitenarkiv
• Abdelmalak, Mohamed Mansour; Faleide, Jan Inge; Planke, Sverre; Theissen-Krah, Sonja; Zastrozhnov, Dmitrii & Breivik, Asbjørn Johan [Vis alle 8 forfattere av denne artikkelen] (2014). Breakup magmatism style on the North Atlantic Igneous Province: insight from Mid-Norwegian volcanic margin. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Breivik, Asbjørn Johan; Blaich, Olav A.; Tsikalas, Filippos; Planke, Sverre & Abdelmalak, Mohamed Mansour [Vis alle 8 forfattere av denne artikkelen] (2014). Structure and degree of magmatism of North and South Atlantic rifted margins. Fulltekst i vitenarkiv
• Abdelmalak, Mohamed Mansour; Faleide, Jan Inge; Planke, Sverre; Breivik, Asbjørn Johan; Gernigon, Laurent & Myklebust, Reidun (2013). Magmatism and break-up on the NE Atlantic: the nature and influence of the lower crustal body on margin structure. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Planke, Sverre; Abdelmalak, Mohamed Mansour; Theissen-Krah, Sonja; Zastrozhnov, Dmitry & Tsikalas, Filipos [Vis alle 12 forfattere av denne artikkelen] (2013). Structure and evolution of the NE Atlantic conjugate margins off Norway and Greenland. Fulltekst i vitenarkiv
• Rai, Abhishek Kumar; Breivik, Asbjørn Johan & Mjelde, Rolf (2013). Lower Crustal Reflectivity bands and Magma Emplacement in Norwegian Sea, NE Atlantic. Fulltekst i vitenarkiv
• Rai, Abhishek Kumar; Breivik, Asbjørn Johan; Mjelde, Rolf & Pedersen, Rolf-Birger (2013). Nature of the seismic crust at the Aegir Ridge: A downward continuation approach. Fulltekst i vitenarkiv
• Planke, Sverre; Sassier, Caroline; Polteau, Stephane; Faleide, Jan Inge; Galland, Olivier & Breivik, Asbjørn Johan [Vis alle 7 forfattere av denne artikkelen] (2013). Salt distribution and sub-salt basins on the conjugate Barents Sea - Northeast Greenland continental shelves. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf; Flueh, Ernst R. & Murai, Yoshio (2013). Magmatic development of the outer Vøring Margin. Fulltekst i vitenarkiv
• Rai, Abhishek Kumar; Breivik, Asbjørn Johan; Mjelde, Rolf; Hanan, Barry; Ito, Garrett & Howell, Samuel M. [Vis alle 8 forfattere av denne artikkelen] (2012). Analysis of converted S-waves and gravity anomaly along Aegir Ridge: implications for crustal lithology. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Mjelde, Rolf; Rai, Abhishek Kumar & Frassetto, Andy (2012). Geophysical survey of the Eggvin Bank and Logi Ridge - Greenland Sea. Fulltekst i vitenarkiv Vis sammendrag

  The northern Greenland Sea has a number of features associated with excess volcanism. These include the Jan Mayen island, the Jan Mayen Plateau north of, and the Eggvin Bank west of Jan Mayen, and the Vesteris Seamount far to the north. In the summer of 2011, we collected an Ocean Bottom Seismometer (OBS) profile across the Eggvin Bank, returning four good data sets. We also collected single-channel reflection seismic (SCS) data along the OBS line. The profile crosses the transform part of the West Jan Mayen Fracture Zone (WJMFZ), which connects seafloor spreading between the Kolbeinsey and Mohn ridges. Between the WJMFZ and the Vesteris Seamount there is a narrow ridge 170-180 km long, ending in a few seamounts in the east. It disturbs the magnetic seafloor anomalies, and has no conjugate on the Norwegian margin. It thus appears to be younger than the Eocene seafloor it lies on. Trend and position points to Traill Ø in East Greenland, which had magmatism at ~36 Ma. We name it the Logi Ridge after Norse mythology, where Logi is the master of fire, brother of Aegir, master of the sea. We have collected five SCS profiles across this ridge in order to study the surrounding sedimentation pattern. We also collected gravity and magnetic data along all profiles. Initial results show two flat-topped seamounts on the Eggvin Bank, and a flat-topped Logi Ridge, indicating that these have been at sealevel. The sedimentary strata show recent vertical movement north of the WJMFZ near the Jan Mayen Plateau, and compression around the Logi Ridge.

• Breivik, Asbjørn Johan (2012). Mantle melting in the NE Atlantic Igneous Province. Fulltekst i vitenarkiv Vis sammendrag

  The northeast Atlantic margins form part of a large mafic igneous province, which has been attributed to the arrival of the Iceland mantle plume. Sill complexes and magmatic underplating formed at the outer margins at breakup, followed by the formation of oceanic crust 2-4 times normal thickness. High magma productivity typically lasted 3-6 Ma after breakup. After that, excess magmatism continued along the Faeroe-Iceland-Greenland Ridge. Other models, ranging from small-scale convection to increased mantle fertility, have also been proposed to explain the excess magmatism. By comparing the oceanic crustal thickness of the volcanic margins with average P-wave velocities, the melting process of the mantle can be estimated. The results indicate elevated mantle temperatures confined to a finite reservoir underneath the margins at breakup time, consistent with a plume model. But additional processes appear to augment the melt production at some margin segments. Later magmatic rejuvenation may also mask original processes in some areas.

• Sayit, Kaan; Breivik, Asbjørn Johan; Mjelde, Rolf & Pedersen, Rolf-Birger (2012). The trace and Pb isotope chemistry of the Jan Mayen Fracture Zone and the extict Aegir Ridge. Fulltekst i vitenarkiv
• Sayit, Kaan; Breivik, Asbjørn Johan; Mjelde, Rolf & Pedersen, Rolf-Birger (2012). The trace and Pb isotope chemistry of the Jan Mayen Fracture Zone and the extinct Aegir Ridge. Fulltekst i vitenarkiv
• Howell, Samuel M.; Breivik, Asbjørn Johan & Mjelde, Rolf (2012). Mantle Convection beneath the Aegir Ridge, a Shadow in the Iceland Hotspot. Fulltekst i vitenarkiv
• Savit, K; Hanan, Barry; Ito, Garrett; Howel, SM; Vogt, Peter & Breivik, Asbjørn Johan [Vis alle 8 forfattere av denne artikkelen] (2012). The trace and Pb isotope chemistry of the Jan Mayen Fracture Zone and the extinct Aegir Ridge. Fulltekst i vitenarkiv
• Rai, Abhishek Kumar; Breivik, Asbjørn Johan & Mjelde, Rolf (2011). Seismic Structure of the Extinct Aegir Ridge in Norwegian Basin, N.E. Atlantic. Fulltekst i vitenarkiv
• Sayit, Kaan; Hanan, Barry; Ito, Garrett; Howell, S.; Vogt, Peter R. & Breivik, Asbjørn Johan [Vis alle 8 forfattere av denne artikkelen] (2011). Geochemistry and Pb Isotopes from the Jan Mayen Fracture Zone and the Extinct Aegir Ridge. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Mjelde, Rolf; Faleide, Jan Inge & Murai, Yoshio (2011). The Eastern Jan Mayen Micro-Continent Volcanic Margin. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Mjelde, Rolf; Raum, Thomas; Faleide, Jan Inge; Murai, Yoshio & Flueh, ER (2010). Crustal structure of the inner mid-Norwegian continental margin – Trøndelag Platform, from wide-angle seismic and potential field data. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan (2010). Volcanic margins – hotspot origin or not? A closer look at the NE Atlantic. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2010). The Norwegian volcanic margin revisited. Fulltekst i vitenarkiv
• Tsikalas, Filippos; Faleide, Jan Inge; Blaich, Olav Antonio; Breivik, Asbjørn Johan; Mjelde, Rolf & Eldholm, O (2009). Late Mesozoic-Cenozoic Evolution of the Conjugate Lofoten-Vesterålen (Nordland VI-VII) and NE Greenland Continental Margins: Implications for the Potentially Developed Petroleum System. Fulltekst i vitenarkiv
• Clark, SA; Ritzmann, Oliver; Faleide, Jan Inge; Mjelde, Rolf; Glørstad, Evy & Leever, K [Vis alle 8 forfattere av denne artikkelen] (2009). Rift basin architecture and crustal thinning in the southwestern Barents Sea. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2009). Northeast Atlantic Igneous Province volcanic margin development. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, Rolf; Blaich, Olav Antonio & eldholm, olav (2009). Structure and Evolution of the NE Atlantic Region and Links to the Arctic. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan & Mjelde, Rolf (2009). Structure and evolution of the continental margin off Norway and the Barents Sea and its conjugate off Greenland. Fulltekst i vitenarkiv
• Mjelde, Rolf; Breivik, Asbjørn Johan & Faleide, Jan Inge (2009). Northeast Atlantic Igneous Province volcanic margin development. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2009). Oceanic Intraplate Magmatism Off The Vøring Volcanic Passive Margin, Norway – Constraints On Origin From Seismic Velocity Structure. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2009). Conjugate volcanic margin breakup of the mid-Norwegian and East Greenland Margins –using crustal scale velocity and thickness data to determine breakup style. Fulltekst i vitenarkiv
• Clark, Stephen Anthony; Ritzmann, Oliver; Faleide, Jan Inge; Mjelde, Rolf; Leever, Karen Agneta & Glørstad-Clark, Evy [Vis alle 8 forfattere av denne artikkelen] (2008). Linking deep structures and basin formation in the Barents Sea. 33rd International Geological Congress, Abstracts. CD-ROM. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2008). Enigmatic Neogene magmatism NE of Iceland - major magmatic underplating off the Norwegian margin. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, Rolf; Ritzmann, Oliver & Engen, Øyvind [Vis alle 8 forfattere av denne artikkelen] (2008). Basin evolution at the Norwegian-Greenland conjugate margins in the NE Atlantic. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2008). Determining volcanic continental margin breakup style on the Norwegian Margin - Which criteria are important and can they be generalized? Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2008). Enigmatic Neogene magmatism NE of Iceland - Major magmatic underplating off the Norwegian margin. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2008). East Greenland – mid-Norway asymmetric conjugate volcanic margin development. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, Rolf; Wilson, Jonas & Eldholm, Olav (2007). NE Atlantic breakup and evolution of the Norwegian-Greenland conjugate volcanic margins. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Engen, Øyvind; Tsikalas, Filippos; Breivik, Asbjørn Johan & Ritzmann, Oliver (2007). Crustal structure of the mainly sheared western Barents Sea-Svalbard margin. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2007). The dynamics of continental breakup-related magmatism on the Norwegian volcanic margin. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf & Tsikalas, Filippos (2007). Timing of Continental breakup at the mid-Norwegian margin, Euromargins 2003 OBS Experiment. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf & Tsikalas, Filippos (2007). Continental breakup and magmatic development of the mid-Norwegian margin, Euromargins 2003 OBS Experiment. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Engen, Øyvind; Tsikalas, Filippos; Breivik, Asbjørn Johan & Ritzmann, Oliver (2007). Opening of the northern North Atlantic and formation of the sheared western Barents Sea-Svalbard and NE Greenland margins. Fulltekst i vitenarkiv
• Tsikalas, Filippos; Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf & Eldholm, Olav (2007). Crustal structure, continental breakup and magmatism at the Lofoten-Vesterålen margin, off Norway, constrained by the Euromargins 2003 OBS Experiment. Fulltekst i vitenarkiv
• Tsikalas, Filippos; Faleide, Jan Inge; Breivik, Asbjørn Johan; Mjelde, Rolf; Wilson, Jonas & Eldholm, Olav [Vis alle 7 forfattere av denne artikkelen] (2007). Structure and evolution of the northern Vøring and Lofoten-Vesterålen margins, and their conjugate NE Greenland margin. Fulltekst i vitenarkiv
• Brandsdottir, Bryndis; Hooft, Emilie; Mjelde, Rolf; Shimamura, Hideki; Murai, Yoshio & Barclay, Andrew [Vis alle 8 forfattere av denne artikkelen] (2006). Evolution of a divergent plate boundary; from the active Kolbeinsey Ridge, N-Iceland to the exinct Ægir Ridge, Norwegian Sea. Fulltekst i vitenarkiv Vis sammendrag

  The continental margin off mid-Norway is a volcanic passive margin created during the earliest Eocene, and large volumes of magmatic rocks were emplaced during and a few M.y. after continental breakup. In 2003, an ocean bottom seismometer/hydrophone survey was acquired on the Vøring and Lofoten-Vesterålen Margins. The main targets are continental breakup processes, early seafloor spreading, and along-margin variation of magma productivity. The P-wave data were modeled by a combined forward ray-tracing and inversion into 2D velocity-depth models. The continent-ocean transition zone is usually well defined as a rapid increase of P-wave velocities at mid- to lower-crustal levels. This transition may occur over a distance of only 15-20 km. Maximum igneous crustal thickness was found to be about 18 km on both of the Euromargins profiles across the outer Vøring Plateau, which is 5-7 km less than reported from older surveys in the area. Lower crustal P-wave velocities of up to 7.3 km s-1 were found at the bottom of the igneous crust here, similar to earlier studies. Magmatic underplating of continental crust was for the first time identified at the Lofoten-Vesterålen margin. At 2 km thickness this is a third of what is typical for the Vøring Plateau, and oceanic crustal thickness adjacent to the continent is close to normal, both showing the distal location of this part of the margin to the Iceland hotspot influence. Continental breakup appears to occur at least 1 M.y. later here than on the Møre Margin to the south. A previously unknown episode of magmatic underplating of oceanic crust off the Vøring Plateau was also identified, creating an igneous crust up to 15 km thick. This episode is completely unrelated to the breakup magmatism, but belongs to a family of Neogene intra-plate magmatism observed in the North Atlantic. The underplating was dated from the inversion of overlying sedimentary strata in the oceanic basin to be Late Miocene.

• Tsikalas, Filippos; Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf & Eldholm, Olav (2006). Crustal structure, continental breakup and magmatism at the Lofoten-Vesterålen margin, off Norway, constrained by the Euromargins 2003 OBS Experiment. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2006). Continent-ocean transition at the northern Vøring Margin, Norway, Euromargins 2003 OBS Experiment. Fulltekst i vitenarkiv Vis sammendrag

  The continental margin off mid-Norway is a volcanic passive margin created during the earliest Eocene, and large volumes of magmatic rocks were emplaced during and a few M.y. after continental breakup. In 2003, an ocean bottom seismometer/hydrophone survey was acquired on the Vøring and Lofoten-Vesterålen Margins. The main targets are continental breakup processes, early seafloor spreading, and along-margin variation of magma productivity. The profile presented here is one of five profiles from the survey crossing the continent-ocean boundary. It crosses the northern part of the Vøring Plateau and continues into the oceanic basin out to magnetic anomaly 21 (~47 Ma). The P-wave data were modeled by a combined forward ray-tracing and inversion into a 2D velocity model. Strong lower crustal reflectivity in the thick igneous section imparted ambiguity on Moho interpretation from the OBS/H data. Gravity modeling was used interactively with the ray-tracing to obtain a consistent model. The forward gravity model was corrected by a lithospheric mantle density model based on estimated thermal expansion. The thermal model was calculated by a 2D finite-element program, using the opening history of the oceanic basin. This procedure removed a ~70 mGal regional misfit, and the final fit between observed and calculated gravity is good. Also upper mantle reflectivity is abundant under the thick igneous crust, limited mostly to a zone 2-4 km below the Moho. This indicates a Moho transition zone where mafic and ultramafic rocks interfinger. The profile shows a rapid transition over a distance of 15-20 km from continent to oceanic crust (COT), similar to earlier results. Maximum igneous crustal thickness was found to be 18 km, and from the COT the thickness decreases to ~6.5 km over a distance of 120 km, indicating magmatism abating over a period of at least ~6 M.y. after continental breakup. Lower crustal P-wave velocities of up to 7.3 km s-1 were found at the bottom of the crust. Combined with modeling of the S-wave data, we conclude that the crust is primarily of igneous origin here, though some continental contamination may exist at middle-lower crustal levels in a ~30 km wide zone underneath the continental slope.

• Wilson, Jonas; Raum, Thomas; Mjelde, Rolf; Faleide, Jan Inge; Breivik, Asbjørn Johan & Murai, Yoshio [Vis alle 7 forfattere av denne artikkelen] (2006). Crustal structure and composition beneath the Trøndelag Platform, mid-Norwegian margin, derived from wide-angle seismic and gravity data. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Wilson, Jonas; Mjelde, Rolf; Ritzmann, Oliver & Breivik, Asbjørn Johan (2006). Crustal structure and deep basin configuration - key observations and modelling constraints. Fulltekst i vitenarkiv
• Ritzmann, Oliver; Faleide, Jan Inge; Breivik, Asbjørn Johan & Mjelde, Rolf (2006). Tectonic development and temperature history of the Vøring area, mid Norway - Task Seismic wave field modelling along deep-seismic transects. Fulltekst i vitenarkiv
• Faleide, Jan Inge; Mjelde, Rolf; Tsikalas, Filippos; Breivik, Asbjørn Johan; Raum, Thomas & Wilson, Jonas [Vis alle 7 forfattere av denne artikkelen] (2006). A regional 3D model of the crustal architecture and evolution of the mid-Norwegian continental margin. Fulltekst i vitenarkiv
• Tsikalas, Filippos; Breivik, Asbjørn Johan; Faleide, Jan Inge; Raum, Thomas; Mjelde, Rolf & Eldholm, Olav (2006). Crustal structure of the Lofoten-Vesterålen margin, off Norway, constrained by new OBS data. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf & Tsikalas, Filippos (2006). Continental breakup and magmatic development of the mid-Norwegian margin, Euromargins 2003 OBS Experiment. Fulltekst i vitenarkiv Vis sammendrag

  The continental margin off mid-Norway is a volcanic passive margin created during the earliest Eocene, and large volumes of magmatic rocks were emplaced during and a few M.y. after continental breakup. In 2003, an ocean bottom seismometer/hydrophone survey was acquired on the Vøring and Lofoten-Vesterålen Margins. The main targets are continental breakup processes, early seafloor spreading, and along-margin variation of magma productivity. The P-wave data were modeled by a combined forward ray-tracing and inversion into 2D velocity-depth models. The continent-ocean transition zone is usually well defined as a rapid increase of P-wave velocities at mid- to lower-crustal levels. This transition may occur over a distance of only 15-20 km. Maximum igneous crustal thickness was found to be about 18 km on both of the Euromargins profiles across the outer Vøring Plateau, which is 5-7 km less than reported from older surveys in the area. Lower crustal P-wave velocities of up to 7.3 km s-1 were found at the bottom of the igneous crust here, similar to earlier studies. Magmatic underplating of continental crust was for the first time identified at the Lofoten-Vesterålen margin. At 2 km thickness this is a third of what is typical for the Vøring Plateau, and oceanic crustal thickness adjacent to the continent is close to normal, both showing the distal location of this part of the margin to the Iceland hotspot influence. Continental breakup appears to occur at least 1 M.y. later here than on the Møre Margin to the south. A previously unknown episode of magmatic underplating of oceanic crust off the Vøring Plateau was also identified, creating an igneous crust up to 15 km thick. This episode is completely unrelated to the breakup magmatism, but belongs to a family of Neogene intra-plate magmatism observed in the North Atlantic. The underplating was dated from the inversion of overlying sedimentary strata in the oceanic basin to be Late Miocene.

• Tsikalas, Filippos; Breivik, Asbjørn Johan; Faleide, Jan Inge; Raum, Thomas; Mjelde, Rolf & Eldholm, Olav (2006). OBS data constrain the crustal structure of the Lofoten-Vesterålen margin, off Norway. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2006). Continental breakup and magmatism at the mid-Norwegian margin, Euromargins 2003 OBS Experiment. Fulltekst i vitenarkiv Vis sammendrag

  The continental margin off mid-Norway is a volcanic passive margin created during the earliest Eocene, and large volumes of magmatic rocks were emplaced during and a few M.y. after continental breakup. In 2003, an ocean bottom seismometer/hydrophone survey was acquired on the Vøring and Lofoten-Vesterålen Margins. The main targets are continental breakup processes, early seafloor spreading, and along-margin variation of magma productivity. The P-wave data were modeled by a combined forward ray-tracing and inversion into 2D velocity-depth models. The continent-ocean transition zone is usually well defined as a rapid increase of P-wave velocities at mid- to lower-crustal levels. This transition may occur over a distance of only 15-20 km. Maximum igneous crustal thickness was found to be about 18 km on both of the Euromargins profiles across the outer Vøring Plateau, which is 5-7 km less than reported from older surveys in the area. Lower crustal P-wave velocities of up to 7.3 km s-1 were found at the bottom of the igneous crust here, similar to earlier studies. Magmatic underplating of continental crust was for the first time identified at the Lofoten-Vesterålen margin. At 2 km thickness this is a third of what is typical for the Vøring Plateau, and oceanic crustal thickness adjacent to the continent is close to normal, both showing the distal location of this part of the margin to the Iceland hotspot influence. In the absence of an early spreading axis jump, continental breakup must have occurred 1-2 M.y. later here than on the Møre Margin to the south. A previously unknown episode of magmatic underplating of oceanic crust off the Vøring Plateau was also identified, creating an igneous crust up to 15 km thick. This episode is completely unrelated to the breakup magmatism, but belongs to a family of Neogene intra-plate magmatism observed in the North Atlantic. The underplating was dated from the inversion of overlying sedimentary strata in the oceanic basin to be Late Miocene.

• Breivik, Asbjørn Johan; Mjelde, Rolf & Faleide, Jan Inge (2006). Magma-starved seafloor accretion in the Norway Basin caused by the Iceland hotspot. Fulltekst i vitenarkiv Vis sammendrag

  The Norway Basin was initiated by continental breakup between northern Europe and Greenland/Jan Mayen in the earliest Eocene (~54Ma). Being part of the North Atlantic Igneous Province, continental breakup and early seafloor spreading produced voluminous magmatism, which subsided as seafloor spreading progressed. An ocean bottom seismometer (OBS) profile acquired in the year 2000 from the Norwegian Møre margin to the extinct spreading axis of the Aegir Ridge was used to estimate variations in magma productivity as the oceanic basin evolved. Due to low magnetic data coverage, a satellite derived gravity map proved suitable to reinterpret the East Jan Mayen Fracture Zone (EJMFZ) system, but no other fracture zones could be identified within the Norway Basin. The revised EJMFZ trace was used to re-evaluate spreading in the Norway Basin, which appears more asymmetric than previously believed, being condensed mostly on the southwestern side. The magnetic track recorded along the OBS profile was used to identify magnetic seafloor spreading anomalies by forward modeling, and projected onto synthetic flow lines half spreading rates were derived along-profile. Maximum rate was above 3 cm/a between A24A and A24b, falling off to ~0.7 cm/a (ultra-slow) by C20 (42.7 Ma) which lasted to the Late Oligocene (25-28 Ma) termination of seafloor spreading. Breakup magmatism created oceanic crust up to 10-11 km thick, tapering down to thin crust by C23 time (51.4 Ma); the increased melt potential was thus spent ~2.5 Ma after continental breakup. While oceanic crust created during ultra-slow spreading is thin (3.9 km), crust created during slow spreading is also thinner than the world average (5.3 vs. 7.1 km), indicating a somewhat depleted mantle source. A V-shaped pattern seen in the gravity field only around the northern part of the Aegir Ridge corresponds to increased crustal thickness in the OBS model, demonstrating Middle Eocene-Early Oligocene northeast migration of asthenosphere zones with slightly increased melt production at a speed of 0.3-0.6 cm/a. The thin crust and lack of fracture zones in the Norway Basin is typical for ultra-slow seafloor spreading, even if much of it was created during slow spreading (~1.5 cm/a half rate). This character may have developed not despite the closeness to the Iceland Hotspot, but because of it, as mantle partially depleted by high magma production during the construction of the aseismic Iceland-Faeroe Ridge to the south was transported to the northeast to feed oceanic accretion. The southern part of the Norway Basin lacks V-shaped ridges and the Aegir Ridge has a deeper axial valley, indicating a lower magma budget than in the north, consistent with this model.

• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Wilson, Jonas; Engen, Øyvind & Eldholm, Olav (2006). Late Mesozoic-Cenozoic evolution of the NE Atlantic region and links to the Arctic. Fulltekst i vitenarkiv
• Breivik, Asbjørn Johan & Mjelde, Rolf (2006). Seismic evidence for the Barents Sea - Svalbard Caledonides. Fulltekst i vitenarkiv Vis sammendrag

  The western Barents Sea and the Svalbard archipelago share a common history of Caledonian basement formation and subsequent sedimentary deposition. Rocks from the period are accessible on Svalbard, but studies of the near offshore areas rely on seismic data and shallow drilling. Offshore mapping is reliable down to the Permian sequence, but multichannel reflection seismic (MCS) data does not give a coherent picture of older stratigraphy. A survey of ten Ocean Bottom Seismometer (OBS) profiles was collected around Svalbard in 1998. Modeling the data by ray-tracing gives whole-crust depth and velocity transects. Results show a highly variable thickness of pre-Permian sedimentary strata. Depth-to-basement and -Moho maps for two areas south of and southwest of Svalbard were produced from this survey. The observed gravity can in some parts of the platform be directly related to velocity variations in the crystalline crust, but often not to basement or Moho depth. The area around the Olga Basin - Sentralbanken High southeast of Svalbard was one of the targets for the survey, and combined velocity and gravity modeling of the OBS data and results, show crustal roots associated with heterogeneous crystalline crust. The area is very similar to the Ural suture zone, and is the first direct indication for an eastern continuation of the Svalbard Caledonides through the Barents Sea. The other target area is located between Bjørnøya and Svalbard, where older deep MCS profiles indicate a westwards dipping suture zone. The OBS data shows that the suture zone is associated with a strong P-wave velocity contrast from east to west. Supported by modeling of the S-wave and gravity data, we conclude that this corresponds to a change from mafic to more felsic composition. Two of the profiles were shot coincident with earlier MCS lines, confirming the crustal root imaged earlier. Combined, these different seismic datasets indicate both a continuous basement high and crustal root trending towards the Billefjorden Fault Zone (BFZ) onshore Svalbard. The eastern side of the BFZ correlates closely with coincident positive gravity and magnetic anomalies on western Ny Friesland, originating from an antiform with high-grade metamorphic Caledonian rocks. A double linear magnetic anomaly appears on the BFZ trend south of Spitsbergen, sub-parallel and located 10-50 km west of the crustal root. Based on this correlation, we propose that the suture or major thrust zone seen south of Svalbard correlates to the BFZ. The preservation of the relationship between the crustal suture, the crustal root, and upper mantle reflectivity south of Svalbard, challenges the large-offset, post-collision sinistral transcurrent movement on the BFZ and other trends proposed in the literature. Also, the seismic data south of Svalbard does not show clear signs of major lateral offsets, as seen in deep seismic data around the British Isles. We conclude that the main Caledonide sutures branched to continue both through Svalbard and through the eastern Barents Sea by collision with one or more microplates caught between Laurentia and Baltica.

• Breivik, Asbjørn Johan; Faleide, Jan Inge & Mjelde, Rolf (2006). MORB-hijacking by the Iceland Plume. Fulltekst i vitenarkiv Vis sammendrag

  The Iceland plume is one of the prime examples supporting the mantle plume theory, i.e., cooling of the Earth’s interior by localized large vertical mass transport. The plume caused pre-breakup and voluminous breakup magmatism on the North Atlantic continental margins, and formed an aseismic ridge from the continental margins to Iceland. According to theory, the plume initially had a broad head affecting a region ~2000 km wide, while a narrow, long-lived trailing stem interacted with the seafloor spreading to create the exceptionally thick igneous crust of Iceland, and to drive asthenosphere zonation away from Iceland to create V-shaped ridges in the oceanic crust around the spreading axes. However, there are centres of magmatism at distance from the plume, spanning from Miocene to recent, which do not fit with the plume theory. Here we present new data to document an unexpected province of diffuse Late Miocene magmatic underplating of older oceanic crust north of the Aegir Ridge, an extinct seafloor spreading axis in the Norway Basin. Based on correlation between the province and the extinct axis, and similarity to the region northeast of the present spreading on the Kolbeinsey Ridge north of Iceland, we present a new model of plume - spreading ridge interaction to explain these two magmatic provinces: The asthenosphere flow out from Iceland ’hijacks’ deeper, low-degree partially molten asthenosphere regions created underneath the spreading ridges and carry these across the terminating fracture zones, to subsequently add to the base of the oceanic crust or to build seamounts.

• Mjelde, Rolf; Breivik, Asbjørn Johan & Faleide, Jan Inge (2006). Crustal transect across the North Atlantic. Fulltekst i vitenarkiv
• Mjelde, Rolf; Breivik, Asbjørn Johan & Faleide, Jan Inge (2006). Crustal profile across the North Atlantic. Fulltekst i vitenarkiv

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