Filippos Tsikalas

• Hansen, Jørgen André; Mondol, Nazmul Haque; Tsikalas, Filippos & Faleide, Jan Inge (2020). Caprock characterization of Upper Jurassic organic-rich shales using acoustic properties, Norwegian Continental Shelf. Marine and Petroleum Geology.  ISSN 0264-8172.  121 . doi: 10.1016/j.marpetgeo.2020.104603 Fulltekst i vitenarkiv. Vis sammendrag

  Our analysis of a comprehensive well log database and complementary mineralogical and geochemical information indicates that the risk for Upper Jurassic shales on the Norwegian Continental Shelf (NCS) to permit severe leakage of hydrocarbons from the reservoir is generally low, even in the case of substantial uplift. The content of brittle minerals, organic content, and compaction are dominant factors that explain the observed discrepancies in acoustic properties of organic-rich caprock shales. In particular, variations in silt-clay content in clay-dominated shales are found to primarily influence sonic velocity and to correlate closely with gamma-ray where the uranium contribution is limited (“grey shales”). Changes in organic content exhibit a stronger density-component and are seen to counteract or mask the compaction effect on velocity and density in Kimmeridgian black shales. The Hekkingen, Draupne and Tau formations are distinctly different from the underlying grey shale formations in acoustic properties, despite that the latter group also contains significant amounts of organic matter. Based on the low permeability and high capillary sealing capacity of clay-dominated shales, we conclude that even for a silty seal, migration through the caprock matrix is highly unlikely. Furthermore, tectonic fracturing is an ineffective leakage mechanism when the seal is poorly consolidated/cemented prior to uplift. Brittleness, related to both mineralogical composition and consolidation, is consequently a crucial parameter for predicting seal integrity in exhumed basins. Our rock physics framework and interpretations relate this rather qualitative parameter to acoustic properties, and thus, to seismic data.

• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2020). Architecture of the evaporite accumulation and salt structures dynamics in Tiddlybanken Basin, southeastern Norwegian Barents Sea. Basin Research.  ISSN 0950-091X.  s 1- 27 . doi: 10.1111/bre.12456 Vis sammendrag

  An extensive, reprocessed two-dimensional (2D) seismic data set was utilized together with available well data to study the Tiddlybanken Basin in the southeastern Norwegian Barents Sea, which is revealed to be an excellent example of base salt rift structures, evaporite accumulations and evolution of salt structures. Late Devonian–early Carboniferous NE-SW regional extensional stress affected the study area and gave rise to three halfgrabens that are separated by a NW-SE to NNW-SSE trending horst and an affiliated interference transfer zone. The arcuate nature of the horst is believed to be the effect of pre-existing Timanian basement grain, whereas the interference zone formed due to the combined effect of a Timanian (basement) lineament and the geometrical arrangement of the opposing master faults. The interference transfer zone acted as a physical barrier, controlling the facies distribution and sedimentary thickness of three-layered evaporitic sequences (LES). During the late Triassic, the northwestern part of a salt wall was developed due to passive diapirism and its evolution was influenced by halite lithology between the three-LES. The central and southeastern parts of the salt wall did not progress beyond the pedestal stage due to lack of halite in the deepest evaporitic sequence. During the Triassic–Jurassic transition, far-field stresses from the Novaya Zemlya foldand- thrust belt reactivated the pre-salt Carboniferous rift structures. The reactivation led to the development of the Signalhorn Dome, rejuvenated the northwestern part of the salt wall and affected the sedimentation rates in the southeastern broad basin. The salt wall together with the Signalhorn Dome and the Carboniferous pre-salt structures were again reactivated during post-Early Cretaceous, in response to regional compressional stresses. During this main tectonic inversion phase, the northwestern and southeastern parts of the salt wall were rejuvenated; however, salt reactivation was minimized towards the interference transfer zone beneath the centre of the salt wall.

• Hansen, Jørgen André; Mondol, Nazmul Haque; Jahren, Jens & Tsikalas, Filippos (2019). Reservoir assessment of Middle Jurassic sandstone-dominated formations in the Egersund Basin and Ling Depression, eastern Central North Sea. Marine and Petroleum Geology.  ISSN 0264-8172.  111, s 529- 543 . doi: 10.1016/j.marpetgeo.2019.08.044 Fulltekst i vitenarkiv. Vis sammendrag

  Reservoir quality assessment was conducted from petrophysical analysis and rock physics diagnostics on 15 wells penetrating Middle Jurassic sandstone reservoir formations in different regions of the eastern Central North Sea. Seismic interpretation on available 3D and 2D seismic reflection data was utilized to map thickness variations and to draw broad correlations to structural features such as salt structures and faults. In the central Egersund Basin, the Sandnes Formation shows good reservoir properties (gross thickness = 107–147 m, N/G = 33–53%) while the Bryne Formation exhibits poorer reservoir quality (N/G < 20%). Both formations display variable reservoir properties and thicknesses on the northern flank of the Egersund Basin and in the Ling Depression (Sandnes Formation: gross thickness 16–26 m, N/G = 11–81%; Bryne Formation: 30–221 m, N/G = 25–70%). The time-equivalent Hugin and Sleipner formations are more locally developed in the southwest part of Ling Depression, and display good-to-excellent and intermediate reservoir quality, respectively. Furthermore, we use the outcomes of the conducted analyses to correlate observations to further exploration on various reservoir target formations and on seismic prediction of reservoir properties. Thus, the risk on reservoir presence and efficiency for the chased targets is considerably reduced. The main remaining risks within the study area are related to source rocks, their maturity, expulsion and migration of hydrocarbon, and the timing of trap formation.

• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2019). Carboniferous graben structures, evaporite accumulations and tectonic inversion in the southeastern Norwegian Barents Sea. Marine and Petroleum Geology.  ISSN 0264-8172.  112 . doi: 10.1016/j.marpetgeo.2019.104038 Fulltekst i vitenarkiv. Vis sammendrag

  High quality reprocessed seismic reflection profiles and available wells were used to study the little studied southeastern Norwegian Barents Sea and east Finnmark Platform. The study area comprises prominent structural elements such as the Haapet, Veslekari, and Signalhorn domes, the West Fedynsky High, and the Tiddlybanken and Nordkapp basins. Seven deep-seated Carboniferous grabens, not formally described earlier, were defined and informally named; and similarly, five evaporite bodies that are tapered stratigraphically above the grabens have been mapped in detail. In the late Devonian, the region comprised a central structural high (Fedynsky High), and two depressions to the north and south, and has subsequently experienced transtensional deformation during a late Devonian-early Carboniferous NE-SW regional extensional phase. As a result, a NW-SE trending graben system was created over the paleotopography, following the inherited Timanian orogeny lineaments and giving rise to the deep-seated Carboniferous grabens. Pennsylvanian to early Permian evaporites were deposited and were characterized by mobile and non-mobile lithologies. The Carboniferous structures controlled the volume, thickness and lithological alterations of the evaporites, and have later influenced the distribution and development of the salt wall and domes. The Haapet, Veslekari, composite West Fedynsky (two domes informally named Alpha and Beta) and Signalhorn domes were generated and the salt wall of the Tiddlybanken Basin was rejuvenated during the late Triassic due to compressional stresses propagating from the evolving Novaya Zemlya fold-and-thrust belt. The domes and salt wall were subsequently reactivated during the upper Jurassic and earliest Cretaceous. Furthermore, we infer that the main phase of reactivation of these structures took place during the early-middle Eocene due to far-field stresses from the transpressional Eurekan/Spitsbergen orogeny.

• Tsikalas, Filippos; Faleide, Jan Inge & Kalac, Amra (2019). New insights into the Cretaceous-Cenozoic tectono-stratigraphic evolution of the southern Lofoten margin, offshore Norway. Marine and Petroleum Geology.  ISSN 0264-8172.  110, s 832- 855 . doi: 10.1016/j.marpetgeo.2019.07.025 Vis sammendrag

  The tectono-stratigraphic evolution of the southern Lofoten margin and its immediate transition towards the northern Vøring margin has been studied in detail utilizing 2D multi-channel seismic reflection profiles, available wells, in addition to gravity and magnetic data. New and better refined structural elements have been mapped within the study area, including (informally named) the West Røst High Fault Complex, Røst Syncline, and Sandflesa High. Furthermore, four main rift phases have been recognised and refined. Late Jurassic-earliest Cretaceous rifting controlled the initial structuring of the main structural elements. Mid-Cretaceous rifting was responsible for initiation of faulting in the West Røst High Fault Complex, while a composite Late Cretaceous rift phase took place and led to westward propagation of fault activity. Paleocene rifting generated new faults and reactivated several earlier faults, prior to continental breakup and seafloor spreading initiation at the Paleocene- Eocene transition. The Bivrost Lineament, separating the southern Lofoten and northern Vøring margins, has exhibited a distinct morphological expression during Cretaceous-Cenozoic and is recognised as a structural “corridor” which segments highs and basins/sub-basins. Furthermore, two dome-shaped features have been observed on the southern Lofoten margin and have probably experienced several phases of growth from Late Cretaceous to Miocene times. The domes are located in close proximity to the outer Vøring margin and Bivrost Lineament that are believed to have facilitated the transfer of imposed compressional deformation on the NE Atlantic margins. Finally, a comparison of the study area to the conjugate Northeast Greenland margin provides valuable insights on the margin evolution in a regional and conjugate setting.

• Tsikalas, Filippos & Eldholm, Olav (2018). Malvinas (Falkland) Plateau structure versus Mjølnir crater: Geophysical workflow template for proposed marine impact craters. Meteoritics and Planetary Science.  ISSN 1086-9379. . doi: 10.1111/maps.13227
• Blaich, Olav Antonio; Tsikalas, Filippos & Faleide, Jan Inge (2017). New insights into the tectono-stratigraphic evolution of the southern Stappen High and its transition to Bjørnøya Basin, SW Barents Sea. Marine and Petroleum Geology.  ISSN 0264-8172.  85, s 89- 105 . doi: 10.1016/j.marpetgeo.2017.04.015
• Zattin, M.; Andreucci, B.; de Toffoli, B.; Grigo, D. & Tsikalas, Filippos (2016). Thermochronological constraints to late Cenozoic exhumation of the Barents Sea Shelf. Marine and Petroleum Geology.  ISSN 0264-8172.  73, s 97- 104 . doi: 10.1016/j.marpetgeo.2016.03.004
• Cappelletti, A; Tsikalas, Filippos; Nestola, Y; Cavozzi, C; Argnani, A; Meda, M & Salvi, F (2013). Impact of lithospheric heterogeneities on continental rifting evolution: Constraints from analogue modelling on South Atlantic margins. Tectonophysics.  ISSN 0040-1951.  608, s 30- 50 . doi: 10.1016/j.tecto.2013.09.026
• Cappelletti, Alessio; Tsikalas, Filippos; Nestola, Yago; Cavozzi, Christian; Argnani, Andrea; Meda, Marco & Salvi, Francesca (2013). Impact of lithospheric heterogeneities on continental rifting evolution: constraints from analogue modelling on South Atlantic margins. Tectonophysics.  ISSN 0040-1951.  608, s 30- 50 . doi: 10.1016/j.tecto.2013.09.026
• Blaich, Olav Antonio; Faleide, Jan Inge & Tsikalas, Filippos (2011). Crustal breakup and continent-ocean transition at South Atlantic conjugate margins. Journal of Geophysical Research (JGR): Solid Earth.  ISSN 2169-9313.  116 . doi: 10.1029/2010JB007686
• Dypvik, Henning; Smelror, Morten; Mørk, Atle & Tsikalas, Filippos (2010). Ejecta geology, In Henning Dypvik; Filippos Tsikalas & Morten Smelror (ed.),  The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event.  Springer.  ISBN 978-3-540-88259-6.  Chapter 6.  s 175 - 194
• Dypvik, Henning; Smelror, Morten; Mørk, Atle & Tsikalas, Filippos (2010). The Mjølnir Impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event, In Henning Dypvik; Filippos Tsikalas & Morten Smelror (ed.),  The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event.  Springer.  ISBN 978-3-540-88259-6.  Introduction.  s 1 - 22
• Dypvik, Henning; Smelror, Morten; Mørk, Atle; Tsikalas, Filippos; Faleide, Jan Inge; Werner, Stephanie & Torsvik, Trond Helge (2010). Geological framework, In Henning Dypvik; Filippos Tsikalas & Morten Smelror (ed.),  The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event.  Springer.  ISBN 978-3-540-88259-6.  Chapter 2.  s 23 - 45
• Shuvalov, Valery; Dypvik, Henning & Tsikalas, Filippos (2010). The impact dynamics, In Henning Dypvik; Filippos Tsikalas & Morten Smelror (ed.),  The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event.  Springer.  ISBN 978-3-540-88259-6.  Chapter 7.  s 195 - 209
• Tsikalas, Filippos & Faleide, Jan Inge (2010). Postimpact deformation due to sediment loading: the Mjølnir paradigm, In Henning Dypvik; Filippos Tsikalas & Morten Smelror (ed.),  The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event.  Springer.  ISBN 978-3-540-88259-6.  Chapter 9.  s 229 - 256
• Tsikalas, Filippos; Faleide, Jan Inge; Gudlaugsson, Steinar Thor & Eldholm, Olav (2010). Impact structure and morphology, In Henning Dypvik; Filippos Tsikalas & Morten Smelror (ed.),  The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event.  Springer.  ISBN 978-3-540-88259-6.  Chapter 3.  s 47 - 73
• Tsikalas, Filippos; Faleide, Jan Inge; Werner, Stephanie; Torsvik, Trond Helge; Gudlaugsson, Steinar Thor & Eldholm, Olav (2010). Impact geophysics and modelling, In Henning Dypvik; Filippos Tsikalas & Morten Smelror (ed.),  The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event.  Springer.  ISBN 978-3-540-88259-6.  Chapter 4.  s 75 - 137
• Antobreh, Andrew Akwasi; Faleide, Jan Inge; Tsikalas, Filippos & Planke, Sverre (2009). Rift-shear architecture and tectonic development of the Ghana margin deduced from multichannel seismic reflection and potential field data. Marine and Petroleum Geology.  ISSN 0264-8172.  26(3), s 345- 368 . doi: 10.1016/j.marpetgeo.2008.04.005
• Blaich, Olav Antonio; Faleide, Jan Inge; Tsikalas, Filippos; Franke, Dieter & Leon, Enric (2009). Crustal-scale architecture and segmentation of the Argentine margin and its conjugate off South Africa. Geophysical Journal International.  ISSN 0956-540X.  178(1), s 85- 105 . doi: 10.1111/j.1365-246X.2009.04171.x
• Blaich, Olav Antonio; Tsikalas, Filippos & Faleide, Jan Inge (2008). Northeastern Brazilian margin: Regional tectonic evolution based on integrated analysis of seismic reflection and potential field data and modelling. Tectonophysics.  ISSN 0040-1951.  458(1-4), s 51- 67 . doi: 10.1016/j.tecto.2008.02.011
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, R; Ritzmann, Oliver; Engen, Øyvind; Wilson, Jonas & Eldholm, O (2008). Structure and evolution of the continental margin off Norway and Barents Sea. Episodes.  ISSN 0705-3797.  31
• Tsikalas, Filippos; Faleide, Jan Inge & Kusznir, Nick J. (2008). Along-strike variations in rifted margin crustal architecture and lithosphere thinning between northern Voring and Lofoten margin segments off mid-Norway. Tectonophysics.  ISSN 0040-1951.  458(1-4), s 68- 81 . doi: 10.1016/j.tecto.2008.03.001
• Tsikalas, Filippos (2005). Mjølnir Crater as a result of oblique impact: asymmetry evidence constrains impact direction and angle, In Christian Koeberl & Herbert Henkel (ed.),  Impact tectonics.  Springer.  ISBN 3540241817.  kapittel.  s 285 - 306
• Tsikalas, Filippos; Faleide, Jan Inge; Eldholm, Olav & Wilson, Jonas (2005). Late Mesozoic-Cenozoic structural and stratigraphic correlations between the conjugate mid-Norway and NE Greenland continental margins, In A.G. Doré & B.A. Vining (ed.),  Petroleum geology: North-West Europe and global perspectives - Proceedings of the 6th Petroleum Geology Conference.  Geological Society.  ISBN 1862391645.  kapittel.  s 785 - 801
• Tsikalas, Filippos; Eldholm, Olav & Faleide, Jan Inge (2005). Crustal structure of the Lofoten-Vesterålen continental margin, off Norway. Tectonophysics.  ISSN 0040-1951.  404(3-4), s 151- 174

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• Dypvik, Henning; Tsikalas, Filippos & Smelror, Morten (ed.) (2010). The Mjølnir impact event and its consequences. Geology and geophysics of a Late Jurassic/Early Cretaceous marine impact event. Springer.  ISBN 978-3-540-88259-6.  318 s.

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• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2020). Anatomy of the evaporite accumulation and salt wall evolution in Tiddlybanken Basin, southeastern Norwegian Barents Sea.
• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2019). Anatomy of the evaporite accumulation and salt wall evolution in Tiddlybanken Basin, southeastern Norwegian Barents Sea..
• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2019). Carboniferous Graben Structures, Evaporite Accumulations and Inversion in the Southeastern Norwegian Barents Sea. Vis sammendrag

  2D regional seismic reflection profiles and well data are used for the investigation of the deep basin architecture in the southeastern Norwegian Barents Sea. The study area contains thick upper Paleozoic to Mesozoic sedimentary strata with prominent structural features comprising the Haapet, Veslekari, and Signalhorn Domes; the Tiddlybanken Basin, Fedynsky High, and eastern Finnmark Platform. Interpretation of selected seismic profiles and time structure maps are presented focusing on the positions, extent, and configurations of the Carboniferous basins. Furthermore, we investigate the relation between the Carboniferous graben structures, evaporites accumulations and inversion in the area. The basin boundary faults of the Carboniferous structures strike NW-SE, and the syn-rift Carboniferous sequences were deposited in half and full grabens. Basins are separated by platforms and structural highs, while basin infill generally dips towards the axis of the grabens, except for the half-graben on the Finnmark Platform where strata dip towards the north and the half-grabens beneath the Haapet Dome where strata dip to the south. In the study area, evaporites are accommodated in the Carboniferous basins and carbonates occupy the structural highs. The deposition of evaporites was constrained by the master faults of the grabens, except for an evaporitic body, which oversteps the rift margins and connects with the southeastern and central parts of the Nordkapp Basin. Furthermore, a thick Triassic succession, with provenance mainly in the southeast, was deposited in the region, while thin Jurassic sediments outcrop at seafloor over the Veslekari Dome and the salt diapir of the Tiddlybanken Basin. Prograding Cretaceous strata mark another phase of regional subsidence in the study area. Several domes are identified in the near base Triassic to the base Cretaceous levels with different shapes, orientation and sizes. The distribution and evolution of the younger domes are partially controlled by the deep-seated Carboniferous structures. Distinct observations including the lateral thickness variations for the uppermost Triassic to the lowermost Cretaceous sediments, the rim syncline development and the onlap at various stratigraphic levels all suggest several phases of doming. We propose a Paleogene timing for the main phase of reactivation of the inverted domes due to Carboniferous graben structures, probably in response to regional compressional stresses.

• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2019). Carboniferous graben structures, evaporite accumulations and tectonic inversion in southeastern Norwegian Barents Sea.. Vis sammendrag

  Improved resolution reprocessed 2D multi-channel seismic reflection profiles, combined with exploration wells and stratigraphic boreholes penetrating upper Paleozoic sequences on the eastern Finnmark Platform were utilized particularly to analyse the Carboniferous graben system, evaporite bodies distribution, domes and salt wall in the southeastern Norwegian Barents Sea and east Finnmark Platform. Seven deep-seated Carboniferous grabens, not previously described and named, were defined and informally named as grabens G1-G7. Five evaporite bodies, named EB1-EB5, have been mapped in detail. During late Devonian, the study area was dominated by a central structural high region (Fedynsky High) rimmed by sag basins to the north and south it. We suggest that late Devonian-early Carboniferous (Mississippian) NE-SW oriented stress regime as suggested for the evolution of the Pechora Basin, eastern Barents Sea, and Olga-Sørkapp region also created the NW-SE striking graben structures (G1-G5) in the southeastern Norwegian Barents Sea, mainly exploiting the Timanian Orogen structural grain. In the early Pennsylvanian, the NE-SW trending Nordkapp Basin dissected the already existing G6 and G7 grabens. Pennsylvanian to early Permian evaporite units were deposited. The temporal relationship suggests that the evaporites were deposited as post-rift sequences within the Carboniferous grabens of the southeastern Norwegian Barents Sea and as syn-rift or early post-rift sequences within the Nordkapp Basin. The discrepancy in syn-rift to post-rift basin conditions affected the distribution and thickness of the accumulated evaporites, partly or fully occupying the available accommodation space. Evaporite bodies EB1, EB3, and EB5 are correlated to the Gipsdalen Group halite and non-halite lithologies (i.e. anhydrite-related compositions) with less thickness, while evaporite body EB4 contained mobile halite lithology and EB2 comprised of transitional lithology from graben margin (non-mobile) to the center (mobile). The deep-seated structures constrained the accumulation and facies variations of the evaporites and strongly controlled the distribution and partially the evolution of the stratigraphically shallower domes. The effect of salt mobilization on the dome evolution depended on the relative amount of lithologies with mobile to immobile properties, and the relative stratigraphic thickness of each unit. The NW-SE trending salt wall evolution is complex, varies along-strike, and has affected the structural development of the Signalhorn Dome that was instigated during late Triassic due to the far-field stresses from the evolving Novaya Zemlya fold-and-thrust belt. The Haapet, Veslekari, Alpha and Beta domes were instigated and the salt wall was rejuvenated during late Triassic due to compressional stresses propagating from the Novaya Zemlya fold-and-thrust belt as these structures were located in the relative proximity. Several studies on the Barents Sea-Svalbard region have similarly recorded the results of far-field compressional stresses attributed to the Novaya Zemlya fold-and-thrust belt. All of the structural elements were mildly reactivated during upper Jurassic and earliest Cretaceous. However, the exact causes of this reactivation are difficult to be deciphered in detail due to lack of dense seismic reflection coverage and relatively poor seismic resolution in the southeastern Norwegian Barents Sea. Prograding shelf platform complex sediments during early Cretaceous buried the domes and the salt wall until reactivation of the deep-seated Carboniferous grabens led to the reactivation of these structures and to the erosion of the post-lower Cretaceous strata over their crest. We infer an early-middle Eocene timing for the main phase of reactivation of the domes and salt wall, probably in response to regional compressional stresses related to the transpressional Eurekan/Spitsbergen orogeny

• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2019). Control of Carboniferous Graben Structures on Evaporite Accumulation and Domes Location in Southeastern Norwegian Barents Sea. Vis sammendrag

  We utilize available seismic and well data, and focus on the distribution, orientation of deep-seated Carboniferous graben structures and their control on the domes in the southeastern Norwegian Barents Sea. We map prominent NW-SE trending that represents Timanian Orogeny trend, deep-seated Carboniferous graben structures separated by platforms and structural highs. Evaporites were accumulated in the deep basins, while carbonates occupied the highs. Several distinct domes at top Gipsdalen to Cretaceous levels are present within the study area, including the Haapet, Veslekari, and Signalhorn domes, and the central domal feature of the Fedynsky High. The spatial analysis of graben structures, evaporite accumulation, and domes reveal that the deep-seated Carboniferous structures strongly control the distribution and partially the evolution of the domes along with facies variations. Effect of salt mobilization on the dome evolution is dependent on the lithological variations (mobile and immobile evaporites and carbonates) and thickness. Lateral thickness variations of the uppermost Triassic to the lowermost Cretaceous sediments, the Cretaceous onlaps to the Jurassic successions and erosion of the residual Cretaceous strata, all suggest a multiphase evolution of the domes. We propose Paleogene timing for the main phase of reactivation of the domes, probably in response to regional compressional stresses.

• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2019). Deep-seated Carboniferous graben structures and reactivation of younger domes in the southeastern Norwegian Barents Sea. Vis sammendrag

  2D regional seismic reflection profiles and well data were used for the mapping of the deep Carboniferous basin architecture in the southeastern Norwegian Barents Sea. Interpretation of selected seismic profiles and time structure maps are presented focusing on the positions, configurations and deformation stages of these basins. Furthermore, we investigate the connection between the Carboniferous graben structures, evaporites accumulations and reactivation of the younger domes in the area. The basin boundary faults and affiliated depo-centers of the Carboniferous structures strike NW-SE, defining structural configurations consisting of half- and full grabens. The basins are separated by platforms and structural highs. The basin fill generally dips towards the axis of the grabens, except for the half-graben on the Finnmark Platform, where strata dip towards the north and the half-grabens beneath the Haapet Dome where strata dip to the south. Evaporites are accommodated in the Carboniferous basins and carbonates occupy the structural highs. The deposition of evaporites was constrained by the master faults of the grabens, except for one evaporite body, which oversteps the rift margins and connects with the southeastern and central parts of the Nordkapp Basin. Several domes are identified at the near base Triassic to the base Cretaceous levels. These have different shapes, orientation and sizes. The distribution and evolution of the younger domes are partially controlled by the deep-seated Carboniferous structures. Lateral thickness variations for the uppermost Triassic to the lowermost Cretaceous sediments, the rim syncline development and the onlap at various stratigraphic levels, all suggest several phases of doming. We propose a Paleogene timing for the main phase of reactivation of the domes due to Carboniferous graben structures, probably in response to regional compressional stresses.

• Tsikalas, Filippos; Faleide, Jan Inge & Kalac, Amra (2019). New insights into the Cretaceous and Cenozoic tectono-stratigraphic evolution of the southern Lofoten and northern Vøring margins, offshore northern Norway. Vis sammendrag

  The northern Vøring and southern Lofoten margins are located offshore northern Norway, and are separated by the Bivrost Lineament. While the Vøring margin is extensively studied, the Lofoten-Vesterålen margin is one of the least explored areas on the Norwegian continental shelf. The tectono-stratigraphic evolution of the study area has been studied in detail utilizing several datasets: 2D multi-channel seismic reflection profiles, well-to-seismic ties and stratigraphic information from four exploration wells, in addition to gravity and magnetic data. The main focus of the work has been on seismic and structural interpretation in order to refine the rift phases that affected the study area and to decipher the eventual role of the Bivrost Lineament, as well as to improve the understanding of the evolution the West Røst High Fault Complex and the outer Lofoten margin. Four main rift phases have been recognised and refined in the study area. Late-Jurassic-earliest Cretaceous rifting controlled the initial structuring of the main structural elements. Mid Cretaceous rifting is responsible for initiation of faulting in the West Røst High Fault Complex, while rifting continued during Late Cretaceous and led to a westward propagation of fault activity. Paleocene rifting reactivated several Late Jurassic-earliest Cretaceous and Cretaceous faults, prior to continental breakup and seafloor spreading initiation at the Paleocene-Eocene transition. The Bivrost Lineament is recognized as a major margin boundary with an uncertain exact location, which segments highs and sub-basins on the northern Vøring and southern Lofoten margins. Furthermore, two dome-shaped features have been observed on the southern Lofoten margin, which probably experienced several phases of growth from Late Cretaceous to Miocene times, reaching their maximum dimensions during Middle Miocene. The tectono-stratigraphic evolution of the study area is compared to the conjugate Northeast Greenland margin, to get a better understanding of the evolution in a regional and conjugate context.

• Tsikalas, Filippos; Faleide, Jan Inge & Kalac, Amra (2019). New insights into the Cretaceous tectono-stratigraphic evolution of the southern Lofoten and northern Vøring margins, offshore northern Norway. Vis sammendrag

  The southern Lofoten and northern Vøring margins are located offshore northern Norway, and are separated by the Bivrost Lineament. While the Vøring margin is extensively studied, the Lofoten margin is one of the least explored areas on the Norwegian continental shelf. The study area is mainly located within the Nordland VI (currently not open for exploration) petroleum province. The tectono-stratigraphic evolution of the southern Lofoten margin and its immediate transition towards the northern Vøring margin has been studied in detail utilizing reprocessed 2D multi-channel seismic reflection profiles, available wells, in addition to gravity and magnetic data (Tsikalas et al., 2019). The southern Lofoten margin is an important area to study the Cretaceous tectono-stratigraphic evolution as the, otherwise deeply buried Cretaceous strata in the Vøring Basin that are locally obscured by intensive magmatic intrusions, are structurally elevated and thus better imaged along the southern Lofoten margin. The study has highlighted details on the Cretaceous evolution that can be particularly important and applicable to the rest of the Norwegian Sea. In this context, beyond the refinements to the regionally dominant Late Jurassic-earliest Cretaceous rifting, there is clear evidence for intra Early Cretaceous (Aptian-Albian) and mid-Cretaceous (Albian-Cenomanian) rifting that affected the study area. More importantly, the study provides details on the onset and evolution of the composite Late Cretaceous rift phase that affected the area and gave rise to prominent westward-dipping low-angle detachment faults. One better refined, the Sandflesa High, and two new structural elements, informally named Røst Syncline and West Røst High Fault Complex, have been defined within the study area. The Sandflesa High is a basement high located southwest of the Røst High near the landward breakup lava boundary, while the Røst Syncline is defined as a narrow but distinctly steep and deep basin separating the Sandflesa High and the Røst High/Utrøst Ridge. The West Røst High Fault Complex represents an updomed structure that lies west of the Røst High and exhibits prominent and intense NE-SW trending and west-dipping low-angle detachment faults. Faulting was initiated to the east and gradually propagated towards west. It was first initiated during Cenomanian-Turonian (early Late Cretaceous), and was followed by almost tectonic quiescence prior to a Campanian? faulting activity that is the most prominent of the various Late Cretaceous rift phases as evidenced by the extensive lateral thickness variations across faults. Followed by an uppermost Cretaceous-Paleocene faulted sequence and an equivalent time rifting stage, Paleocene faults are clearly observed to be steeper in comparison to the Cretaceous faults. Regional conjugate correlations between the southern Lofoten and East/Northeast Greenland margins show that low-angle Late Cretaceous detachment faults, with a possible similar onset of the main rift phase in middle Campanian, are characteristic for both conjugate margins. Finally, the Bivrost Lineament separates the Lofoten-Vesterålen and northern Vøring margins and is defined as a structural “corridor” with clear termination of main structural elements in its vicinity. The study shows that the lineament exhibits only a minimal expression of an obvious composite lateral offset. Furthermore, the Bivrost Lineament was a low-relief Late Jurassic-Early Cretaceous accommodation zone, which experienced reactivation during Late Cretaceous-Paleocene rifting.

• Hassaan, Muhammad; Faleide, Jan Inge; Gabrielsen, Roy Helge & Tsikalas, Filippos (2018). Correlation between the Carboniferous graben structures, salt accumulations and inversion in the southeastern Norwegian Barents Sea.
• Blaich, Olav Antonio; Tsikalas, Filippos & Faleide, Jan Inge (2017). Tectono-stratigraphic evolution of the Southern Stappen High and its transition to Bjørnøya Basin, SW Barents Sea. Vis sammendrag

  Within the context of the southwestern Barents Sea, the southern Stappen High and its transition to the Bjørnøya Basin are more or less still underexplored. Improved quality seismic reflection data are utilised to describe new insights into the Paleozoic to early Cenozoic tectono-stratigraphic evolution of the area, as well as to discuss the structural inheritance and the rift development. Well-defined syn-rift wedges and better resolution images for both the deep Carboniferous and Permian successions are revealed. In particular, both the mid-Carboniferous and Late Permian-earliest Triassic extensional phases are characterized by widespread NE-SW oriented normal faults that are mostly westward dipping. Although Triassic is mostly considered as a tectonically stable period in the Barents Sea, in the Stappen High proper there is clear identification of a localised depocentre (named herein “Intra Stappen Basin”) that extends for ~70 km where syn-tectonic geometries characterize the late Paleozoic and Triassic deposits, indicating tectonically active bounding faults. Regional correlation to Middle and Upper Triassic outcrops in southwestern Svalbard reveals possible similarities to progradation from a west-northwest Northeast Greenland provenance as an additional western sediment source area during the Triassic. Thin but distinct Jurassic sequences are expected to be present on Stappen High associated with prominent regional NW-SE extension throughout Late Jurassic that culminated during the earliest Cretaceous. Furthermore, structural and stratigraphic relations are observed within the study area that clearly indicate a distinct early Aptian rift phase with increasing evidence for its occurrence in the southwestern Barents Sea. Late Cretaceous fault activity was concentrated mostly at the greater Knølegga Fault Complex zone in southwest Stappen High with thick Late Cretaceous sequences bounded by impressive low-angle west-dipping detachment faults, implying a shift at that time from a brittle to a more ductile structural regime. During early Cenozoic, the study area is located at the proximity of the paleo-coastline and paleo-shelf edge for both Paleocene and Eocene gravity mass-waste deposits. These are most probably related to a progressively evolving steep bathymetric gradient between the developing margin, mainly towards the west and to the south, and uplifted areas in the region.

• Faleide, Jan Inge; Abdelmalak, Mohamed Mansour; Shephard, Grace; Torsvik, Trond Helge; Gaina, Carmen; Tsikalas, Filippos; Blaich, Olav Antonio; Planke, Sverre & Myklebust, Reidun (2017). Quantification and restoration of pre-drift extension across NE Atlantic conjugate margins.
• Tsikalas, Filippos; Blackley, Graig; Alzeni, Francesco; Van Noorden, Michiel; Uncini, Giuseppe; Farrer, Gregg & Mavilla, Nicola (2017). Kobbe Formation reservoir potential outside Hammerfest Basin in the light of Aurelia (7222/1-1) well results. Vis sammendrag

  Following the successful Middle Triassic play at the Goliat discovery/field in Hammerfest Basin, intense exploration efforts have been made in recent years in the rest of the Barents Sea (Bjarmeland Platform, eastern Loppa High, Nordkapp Basin) in mapping and drilling several prospects with Kobbe Formation reservoir as, in most of the cases, the main target (secondary targets including Klappmyss and Snadd formations). At Goliat, the Kobbe play is composed of four-way down-faulted rollovers with fluvial to deltaic reservoir sandstones of the Middle Triassic Kobbe Formation sourced from Lower and Middle Triassic shales and sealed by Carnian shales. The Goliat oil discovery in the Kobbe Formation in 2005 was a “game changer” as it opened a new play concept in the Hammerfest Basin on top of the successful Upper Triassic-Middle Jurassic Realgrunnen Subgroup play in the area. Triassic sediment provenance areas are well constrained by regional seismic and well correlations in the entire Barents Sea. Although locally northwards prograding wedges are observed offlapping the Finnmark Platform with provenance from uplifted Fennoscandia, the major provenance areas for the Triassic sediments outside the Hammerfest Basin were Novaya Zemlya and the Ural Mountains. During Induan-Ladinian times, marginal marine facies of the Havert, Klappmyss and Kobbe formations onlapped the eastern flank of the paleo-Loppa High and, in an elongated manner, were also deposited farther to the northeast along the Bjarmeland Platform at the Hoop Fault Complex. Farther west in the western Barents Sea, the Lower to Middle Triassic sequences, including the Kobbe Formation equivalents, comprise condensed sections, consisting of distal organic-rich deep marine mudstones and minor sandstones. The Aurelia well (7222/1-1; completed Aug. 2016) in block 7222/1 of PL226 (operated by Eni Norge) is located on the northeastern part of the Loppa High proper and is the latest well to target the Kobbe Formation reservoir as the main target along the SW-NE elongated, Anisian paleo-shoreline along the eastern Loppa High and Hoop Fault Complex area. The well results indicate a poor quality sandstone reservoir of 22 m with traces of gas in the Kobbe Formation, as well as minor gas shows in two moderate reservoir quality water-bearing sandstone levels (Carnian and Ladinian) within the Snadd Formation of 56 and 18 m, respectively. Characteristic clinoform surfaces were mapped in the available 3D seismic in Aurelia and several seismic amplitude anomalies are structurally comformable with the prospect. Despite the encouraging pre-drill accounts for presence of sandy deposits at the topset of these clinoform successions and their deltaic counterparts, the well encountered only heretolithic facies with poor reservoir quality at the Kobbe Formation main target. The Aurelia well results may, therefore, challenge the expectations for viable Kobbe Formation reservoir potential away from the Hammerfest Basin where the proximity to the Fennoscandia provenance and the interplay between fault-controlled changes in the delta system and facies appear to be the main reservoir controlling factors.

• Tsikalas, Filippos; Uncini, Giuseppe; Mavilla, Nicola; Staine, Ivan; Casaglia, Fransesca; Leutscher, Johan; Gennaro, Matteo; Arrigoni, Veronica; Gustafsson, Lars-Erik; Galimberti, Roberto & Daturi, Cristina (2017). Goliat discovery ‒ A knowledge-based approach, persistence, and the first commercial oil development in the Norwegian Arctic. Vis sammendrag

  The history of the first commercial oil discovery and development in the Barents Sea, made by Eni Norge, dates back to 1997 when the license acreage was awarded. The first well was drilled in September 2000 and discovered 43 m of oil column in the Upper Triassic part of the Realgrunnen Subgroup. The Goliat play is a four-way rollover down-faulted structure with fluvial deltaic Norian sandstones sourced by Upper Jurassic shales. The Goliat structure is located on the southern edge of the Hammerfest Basin and in the initial interpretations Goliat was considered to be too far away from the main kitchen area to the west of the Hammerfest Basin, especially in comparison with other larger structures closer to the basin axis. The Goliat discovery in 2000 came after 20 years of exploration drilling in the Barents Sea with just one commercial discovery, i.e. the greater Snøhvit gas field (brought on stream in 2007), over 54 exploration wells at that time. As a consequence, the discovery of Goliat came as a great surprise for the Norwegian oil industry and resulted in the widespread acceptance of Norsk Agip/Eni Norge’s innovative geological concept of “long-distance” migration and oil entrapment at the “basin margins/borders”. Of particular importance are the results of the third well in Goliat drilled in 2005. In addition to the discovered hydrocarbon column of 68 m in the Realgrunnen reservoir, the well penetrated an oil column of 80 m in the fluvial to deltaic sandstones of the Middle Triassic Kobbe Formation, which was the secondary well target but subsequently became the main oil pool in the Goliat Field. The oil in the Kobbe Formation is sourced from Lower and Middle Triassic shales. The results of the third well were a “game changer” for the Goliat discovery. The oil discovery in the Kobbe Formation opened a new play concept in the Hammerfest Basin and provided a solid basis for a viable development, the first oil development in the Norwegian Arctic. Today, the Goliat Field is operated by Eni Norge with a 65% interest, in partnership with Statoil 35%. Goliat is the first oil field to come on stream (March 2016) in the Norwegian part of the Barents Sea. Located at 71°30' North, the field is also the world’s northernmost offshore development. Recoverable reserves are estimated to be 174 million BOE and according to the current development scheme the field will be produced through 22 wells all of which are tied back to the Goliat FPSO. Goliat represents a valuable legacy for Eni Norge. The Goliat Field is the result of a challenging, long and successful exploration and appraisal campaign of Eni Norge in the Norwegian Arctic. The established and refined play model for Goliat has been applied to make the additional oil discoveries of Nucula in the eastern vicinity of Hammerfest Basin and Johan Castberg in the Bjørnøya Basin. Historically, top seal failure, leakage and oil biodegradation were the major risk parameters in shallow buried structures in Barents Sea. With the build-up of deep geologic knowledge, Eni Norge is now able to tackle the additional risk elements, such as locally unpredictable reservoir facies distribution and complex migration pathways that have been somewhat underestimated in the initial play models. Over the years, the company has built an important database and a knowledge-based approach to the exploration of the Barents Sea. The use of the latest technologies, dedicated R&D projects and the drilling of appraisal wells to confirm the hydrocarbon accumulations have allowed the company to grow its reserve base through exploration and, ultimately, to increase daily production substantially when the Goliat Field came on stream in March 2016.

• Faleide, Jan Inge; Planke, Sverre; Abdelmalak, Mohamed Mansour; Zastrozhnov, Dmitrii; Wong, P.W.; Shephard, Grace; Indrevær, Kjetil; Tsikalas, Filippos; Gabrielsen, Roy Helge; Gernigon, Laurent; Blaich, Olav A. & Myklebust, Reidun (2016). Basin architecture and evolution at NE Atlantic conjugate margins.
• Faleide, Jan Inge; Wong, Po Wan; Gabrielsen, Roy Helge; Tsikalas, Filippos; Blaich, Olav Antonio; Planke, Sverre & Myklebust, Reidun (2015). Basin evolution at the SW Barents Sea margin and its conjugate off NE Greenland.
• Faleide, Jan Inge; Breivik, Asbjørn Johan; Blaich, Olav A.; Tsikalas, Filippos; Planke, Sverre; Abdelmalak, Mohamed Mansour; Mjelde, Rolf & Myklebust, Reidun (2014). Structure and degree of magmatism of North and South Atlantic rifted margins.
• Faleide, Jan Inge; Wong, P.W.; Gabrielsen, Roy; Tsikalas, Filippos; Blaich, Olav A.; Planke, Sverre & Myklebust, Reidun (2014). Basin evolution at the SW Barents Sea margin and its conjugate off NE Greenland.
• Blaich, Olav Antonio; Faleide, Jan Inge & Tsikalas, Filippos (2009). Conjugate Margin Studies in the South Atlantic.
• 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.
• 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.
• 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.
• Watson, J.G.; Kusznir, Nick J.; Faleide, Jan Inge; Tsikalas, Filippos & Roberts, A. (2009). Volcanic rifted margin asymmetry and pre-breakup sag-sequences: North Atlantic examples.
• Blaich, Olav Antonio; Tsikalas, Filippos; Faleide, Jan Inge; Leon, Enric & Sakariassen, Rune (2008). Potential field data and modelling as robust supplementary and constraining tools on crustal structure architecture at frontier margins: Examples from the northeastern Brazilian margin, and the conjugate Argentine-Namibia margins.
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, Rolf; Ritzmann, Oliver; Engen, Øyvind; Wilson, Jonas & Eldholm, Olav (2008). Basin evolution at the Norwegian-Greenland conjugate margins in the NE Atlantic.
• Gisler, Galen Ross & Tsikalas, Filippos (2008). Insights into gravitational collapse and resurge infilling on marine sedimentary-target impact craters revealed by refined numerical simulations of the Mjølnir Crater.
• Tsikalas, Filippos & Faleide, Jan Inge (2008). Post-impact structural crater modification due to sediment loading: An overlooked process.
• Watson, J.G.; Kusznir, Nick; Tsikalas, Filippos & Faleide, Jan Inge (2008). Asymmetry of the Norwegian and East Greenland conjugate rifted continental margins.
• Antobreh, Andrew Akwasi; Faleide, Jan Inge; Tsikalas, Filippos & Planke, Sverre (2007). Crustal architecture of the Ghana transform margin deduced from combined interpretation of MCS data and 2D gravity modelling.
• Blaich, Olav Antonio; Tsikalas, Filippos & Faleide, Jan Inge (2007). Crustal-scale geometries and architecture along the Northeastern Brazilian margin based on integrated analysis of seismic reflection and potential field data and modelling.
• Blaich, Olav Antonio; Tsikalas, Filippos & Faleide, Jan Inge (2007). Crustal-scale geometries and architecture along the Northeastern Brazilian margin based on integrated analysis of seismic reflection and potential field data and modelling.
• Blaich, Olav Antonio; Tsikalas, Filippos & Faleide, Jan Inge (2007). Northeastern Brazilian margin: regional tectonic evolution based on integrated analysis of seismic reflection and potential field data and modelling.
• 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.
• Breivik, Asbjørn Johan; Faleide, Jan Inge; Mjelde, Rolf & Tsikalas, Filippos (2007). Timing of Continental breakup at the mid-Norwegian margin, Euromargins 2003 OBS Experiment.
• Faleide, Jan Inge; Engen, Øyvind; Tsikalas, Filippos; Breivik, Asbjørn Johan & Ritzmann, Oliver (2007). Crustal structure of the mainly sheared western Barents Sea-Svalbard margin.
• 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.
• 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.
• 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.
• Tsikalas, Filippos & Faleide, Jan Inge (2007). Post-impact structural crater modification due to sediment loading: an overlooked process.
• Tsikalas, Filippos & Faleide, Jan Inge (2007). Reconstruction of the original impact-crater relief for Mjølnir and Chicxulub craters reveals the importance of post-impact crater modification processes due to sediment loading.
• Tsikalas, Filippos & Faleide, Jan Inge (2007). Reconstruction of the original impact-crater relief for Mjølnir, Chicxulub and Bosumtwi impact craters reveals surprisingly shallow structures: Did we miss something?.
• Tsikalas, Filippos & Faleide, Jan Inge (2007). Reconstruction of the original impact-crater relief for Mjølnir, Chicxulub and Bosumtwi impact craters reveals surprisingly shallow structures: Did we miss something?.
• Tsikalas, Filippos; Faleide, Jan Inge; Breivik, Asbjørn Johan; Mjelde, Rolf; Wilson, Jonas; Eldholm, Olav & Kusznir, Nick (2007). Structure and evolution of the northern Vøring and Lofoten-Vesterålen margins, and their conjugate NE Greenland margin.
• Dypvik, Henning; Tsikalas, Filippos; Smelror, Morten & Faleide, Jan Inge (2006). Towards a better understandning of continental shelf impacts: A pontential drilling of the Mjølnir Crater (Barents Sea).
• 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. 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.

• Faleide, Jan Inge; Mjelde, Rolf; Tsikalas, Filippos; Breivik, Asbjørn Johan; Raum, Thomas; Wilson, Jonas & Eldholm, Olav (2006). A regional 3D model of the crustal architecture and evolution of the mid-Norwegian continental margin.
• 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.
• 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.
• 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.
• 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.
• Tsikalas, Filippos & Faleide, Jan Inge (2006). Quantification of the significance of post-impact crater deformation through the study of Mjølnir and Chesapeake Bay craters: differential compaction, changes in geophysical signature response, and reconstruction of the original crater relief.
• Tsikalas, Filippos & Faleide, Jan Inge (2006). Quantification of the significance of post-impact crater deformation through the study of Mjølnir and Chesapeake Bay craters: differential compaction, changes in geophysical signature response, and reconstruction of the original crater relief.
• Dypvik, Henning; Mørk, Atle; Tsikalas, Filippos; Bremer, Gerd M Andersen; Faleide, Jan Inge; Smelror, Morten & Sandbakken, Pål (2005). The Mjølnir Impact Crater - Core Exhibition.
• Dypvik, Henning; Tsikalas, Filippos; Faleide, Jan Inge & Smelror, Morten (2005). A potential drilling of the Mjølnir Crater (Barents Sea).
• Dypvik, Henning; Tsikalas, Filippos; Faleide, Jan Inge & Smelror, Morten (2005). Towards a better understanding of continental shelf impacts: A potential drilling of the Mjølnir Crater (Barents Sea).
• Faleide, Jan Inge; Andriessen, P.A.M.; Jokat, W; Scheck-Wenderoth, M.; Geoffroy, L.; Hertogen, J.; Mjelde, Rolf & Tsikalas, Filippos (2005). Dynamics of conjugate volcanic margins.
• Faleide, JI; Mjelde, Rolf; Tsikalas, Filippos; Breivik, Asbjørn Johan; Raum, Thomas Johan; Wilson, J & Eldholm, Olav (2005). EUROMARGINS research on the Norwegian continental margin - towards a regional 3D model of the crustal architecture and evolution.
• Faleide, JI; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, Rolf; Wilson, J & Eldholm, Olav (2005). NE Atlantic Breakup and Evolution of the Norwegian-Greenland Conjugate Volcanic Margins.
• Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, Rolf & Eldholm, Olav (2005). NE Atlantic breakup and evolution of the Norwegian-Greenland Conjugate Volcanic margins: Field Evidence to the Great Plume Debate.
• Tsikalas, Filippos & Faleide, Jan Inge (2005). Post-impact deformation of impact craters: towards a better understanding through the study of Mjølnir crater.
• Tsikalas, Filippos; Faleide, Jan Inge; Eldholm, Olav & Wilson, Jonas (2005). Late Mesozoic-Cenozoic structural and stratigraphic correlations between the conjugate mid-Norway and NE Greenland continental margins, In A.G. Doré & B.A. Vining (ed.),  Petroleum Geology: North-West Europe and Global Perspectives � Proceedings of the 6th Petroleum Geology Conference.  GSL.  ISBN 1862391645.  785-801.  s 785 - 801
• Tsikalas, Filippos; Faleide, JI; Breivik, Asbjørn Johan; Eldholm, Olav; Mjelde, Rolf & Raum, Thomas Johan (2005). New OBS data constrain, the crustal structure of the Lofoten-Vesterålen margin off Norway.
• Tsikalas, Filippos; Faleide, JI; Breivik, Asbjørn Johan; Mjelde, Rolf & Eldholm, Olav (2005). NE Atlantic breakup and evolution of the Norwegian-Greenland Conjugate Volcanic Margins: Field evidence to the great plume debate.
• Tsikalas, Filippos; Faleide, JI; Eldholm, Olav; Breivik, Asbjørn Johan & Mjelde, Rolf (2005). Crustal structure of the Lofoten-Vesterålen continental margin off Norway.
• Tsikalas, Filippos; Faleide, JI; Eldholm, Olav & Wilson, J (2005). Conjugate mid-Norway and NE Greenlandcontinental margins: Late Mesozoic-Cenozoic tectono-stratigraphic correlations and margin evolution.
• Tsikalas, Filippos; Faleide, JI; Wilson, J & Eldholm, Olav (2005). Late Mesozoic-Cenozoic evolution of the conjugate mid-Norway and NE Greenland continental margins.
• Tsikalas, Filippos; Kusznir, Nick & Faleide, Jan Inge (2005). Along-strike variations in crustal architecture and depth-dependent lithosphere stretching between northern Vøring and Lofoten segments off mid-Norway.
• Tsikalas, Filippos; Papamarinopoulos, Stavros & Shuvalov, Valery (2005). The origin of multi-ringed concentric morphology of Atlantis capitol and its relations to the Platonic scripts.
• Tsikalas, Filippos; Shuvalov, Valery & Papamarinopoulos, Stavros (2005). A new geophysical interpretation of the Platonic multi-ringed concentric morphology of Atlantis capitol based on numerical simulations.
• Faleide, Jan Inge; Mjelde, Rolf; Tsikalas, Filippos; Breivik, Asbjørn Johan; Raum, Thomas; Wilson, Jonas & Eldholm, Olav (2005). EUROMARGINS research on the Norwegian continental margin – towards a regional 3D model of the crustal architecture and evolution.
• Faleide, Jan Inge; Tsikalas, Filippos; Breivik, Asbjørn Johan; Mjelde, Rolf; Wilson, Jonas & Eldholm, Olav (2005). NE Atlantic breakup and evolution of the Norwegian-Greenland conjugate volcanic margins.
• Tsikalas, Filippos; Faleide, Jan Inge; Breivik, Asbjørn Johan; Eldholm, Olav; Mjelde, Rolf & Raum, Thomas (2005). New OBS data constrain the crustal structure of the Lofoten-Vesterålen margin off Norway.
• Tsikalas, Filippos; Faleide, Jan Inge; Breivik, Asbjørn Johan; Mjelde, Rolf; Eldholm, Olav & Wilson, Jonas (2005). NE Atlantic breakup and evolution of the Norwegian-Greenland conjugate volcanic margins: field evidence to the Great Plume Debate.
• Tsikalas, Filippos; Faleide, Jan Inge; Eldholm, Olav; Breivik, Asbjørn Johan & Mjelde, Rolf (2005). Crustal structure of the Lofoten-Vesterålen continental margin off Norway.

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