Changes at the Top of the World through Volcanism and Plate Tectonics: NOR-R-AM2

• Janocha, Julian; Grundvåg, Sten-Andreas; Stemmerik, Lars; Olaussen, Snorre; Thomsen, Tonny B. & Stockli, Daniel F. [Vis alle 9 forfattere av denne artikkelen] (2026). Detrital zircon provenance of the Upper Devonian to Permian Billefjorden and Gipsdalen groups of Svalbard – influence of rifting on sediment routing and basin connectivity. Norwegian Journal of Geology. ISSN 2387-5844. 106(1), s. 1–48. doi: 10.17850/njg106-1-2. Fulltekst i vitenarkiv Vis sammendrag

  Provenance studies based on U–Pb dating of detrital zircons are routinely applied in basin analysis and source-to-sink studies to decipher ancient sediment pathways and the tectonic events that shaped them. The Norwegian Svalbard Archipelago, situated in the high Arctic, hosts a well-preserved upper Paleozoic sedimentary succession, deposited in the aftermath of the Caledonian Orogeny and influenced by shifting regional tectonics, which led to the formation of diverse sedimentary basins. The lower, clastic-dominated portion of the succession records a transition from extensive, pre-rift basins hosting Late Devonian–Mississippian strata (Billefjorden Group) to narrow, fault-bounded, north-south trending rift basins hosting middle Carboniferous–lowermost Permian strata (lower Gipsdalen Group). Despite its significance, the detrital zircon age signatures and sediment provenance of this succession have received limited attention. In this study, we present new detrital zircon age data from 41 samples spanning Late Devonian to lower Permian strata across all major late Paleozoic basins in Svalbard. We analyse the zircon age signatures of individual basin-fill successions and explore the role of regional and local tectonics in driving spatial and temporal changes in sediment provenance and routing during the late Paleozoic. Particular attention is given to the connectivity of pre-rift sedimentary basins, and shifts in provenance linked to the onset of localized rifting during the middle Carboniferous. Our data reveal significant provenance variability across the basins. Key findings include evidence of predominant sediment sourcing from northeastern Greenland during deposition of the Billefjorden Group (latest Devonian to Mississippian pre-rift phase). Similar zircon age signatures across the investigated basins suggest connectivity between pre-rift depocentres. The Billefjorden Trough shows signs of increasing isolation with continued rifting and subsidence. This study provides new insights into the post-Caledonian tectonosedimentary evolution of the region

• Sartell, Anna Marie Rose; Söderlund, U.; Senger, Kim; Kjøll, H. J. & Galland, Olivier (2025). A Review of the Spatiotemporal Evolution of the High Arctic Large Igneous Province, and a New U‐Pb Age of a Mafic Sill Complex on Svalbard. Geochemistry Geophysics Geosystems. 26(12). doi: 10.1029/2024gc011842. Fulltekst i vitenarkiv Vis sammendrag

  The High Arctic Large Igneous Province (HALIP) formed in the circum‐Arctic during the Cretaceous. The timing and duration of emplacement of these mafic magmas are important for understanding the climatic and environmental effects, yet many uncertainties remain. The dating methods used vary greatly between different regions. For example, the mafic intrusions in Svalbard have mainly been dated using the 40 K/ 40 Ar method, which is more sensitive to overprinting at lower temperatures. This is problematic especially in the Arctic, where the Eocene Eurekan orogeny has impacted the intrusions post‐emplacement. Meanwhile, in the Canadian Arctic, 206 Pb/ 238 U dating on zirconium minerals has been the most common method employed, which requires much higher temperatures to be reset. We present a new compilation of ages for HALIP igneous and volcanic rocks in the circum‐Arctic, derived from a thorough review and reassessment of previously reported data. This compilation applies rigorous, method‐specific criteria to evaluate the reliability of existing HALIP age determinations, ensuring traceability and applicability for future data sets. By establishing a robust framework for assessing age data, this approach enhances the reliability of geological interpretations of HALIP magmatism, and highlights, for example, the spatial migration of peak magmatic activity through time in the High Arctic. To improve our understanding of the temporal evolution of the HALIP, we also present a new 206 Pb/ 238 U baddeleyite isotopic dilution thermal ionization mass spectrometry age from Svalbard. The new weighted mean 206 Pb/ 238 U age from Svalbard, 123.3 ± 1.6 Ma, is based on six samples belonging to one large sill. This age is in perfect agreement with existing published 206 Pb/ 238 U and 40 Ar/ 39 Ar ages, and suggests magma emplacement on Svalbard between 124.7 ± 0.3 and 120.2 ± 1.9 Ma ago.

• Galland, Olivier; Sartell, Anna Marie Rose; Horota, Rafael Kenji; Kjøll, Hans Jørgen; Runge, Jonathan J. S. & Midtkandal, Ivar [Vis alle 7 forfattere av denne artikkelen] (2025). Stratigraphic Influence on Emplacement and 3‐Dimensional Structure of a Large Mafic Sill in Sedimentary Strata. Basin Research. ISSN 0950-091X. 37(4). doi: 10.1111/bre.70047. Fulltekst i vitenarkiv Vis sammendrag

  Sills are fundamental elements of volcanic plumbing systems emplaced in sedimentary basins. Even though sills are commonly considered simple, planar concordant igneous sheets, they are actually complex 3‐dimensional objects. Detailed knowledge of the 3D structure of sills and their host rocks is of primary relevance to better constrain the emplacement mechanisms and the impacts of sills on sedimentary basins. This study describes the results of 3‐dimensional geological mapping of a large (~14 × 9 km), well‐exposed Early Cretaceous dolerite sill in Central Spitsbergen, Svalbard, Arctic Norway, using a combination of digital outcrop modelling and field mapping. The sill was emplaced within Upper Palaeozoic sedimentary formations of Svalbard. It is made of distinct segments emplaced at different stratigraphic levels of the host rock stratigraphy. The mapping shows a clear stratigraphic control on the intrusion morphology. Sill segments emplaced at the boundary between two formations, which mark a strong lithological and rheological boundary, are straight and concordant. Conversely, segments emplaced within a more homogeneous formation exhibit more irregular, locally discordant shapes. The sill segments emplaced at distinct stratigraphic levels are connected by steeply dipping steps, which formed through dilatant shearing between the tips of the sill segments. The preferred NW‐SE orientation of the steps and the thinning of the sill towards the SE suggests a propagation direction of the magma towards the SE. Our study shows how 3‐dimensional knowledge of igneous intrusions is key for revealing their emplacement mechanisms.

• Ershova, Victoria; Stockli, Daniel; Gaina, Carmen; Khudoley, Andrey & Shimanskiy, Sergey (2025). When Big Rivers Started to Drain to the Arctic Basin: A View from the Kara Sea. Geosciences. 15(9). doi: 10.3390/geosciences15090342. Fulltekst i vitenarkiv Vis sammendrag

  This study provides new constraints on the paleogeographic evolution of the Arctic during the Mesozoic. U–Pb geochronology of detrital zircon and rutile grains, together with (U–Th)/He zircon thermochronological data from the uppermost Middle Jurassic to Cretaceous strata of the Sverdrup well in the Kara Sea, reveals a major shift in sediment provenance. Two distinct age populations of detrital zircon define this transition: Group 1 (Middle Jurassic–Hauterivian) shows dominant Neoproterozoic–Cambrian (ca. 700–500 Ma) and Paleozoic (ca. 350–290 Ma) peaks, whereas Group 2 (Aptian–Albian) is characterized by prominent Paleoproterozoic (ca. 1980–1720 Ma), Paleozoic (ca. 350–255 Ma), and Early Mesozoic (ca. 240–115 Ma) ages. Corresponding variations in (U–Th)/He zircon ages—from a Triassic peak (~225 Ma) in Group 1 to a dominant Early Cretaceous peak (~140 Ma) in Group 2—support a switch from a proximal to more distal sediment source. We propose that the emergence of large continent-scale river systems transported clastic material from the southern margin of the Siberian Craton to the Arctic Ocean starting in the late Early Cretaceous. The development of a significant freshwater supply potentially initiated a thick low-salinity layer within the surface waters of the central Arctic Ocean, possibly leading to the onset of a strong salinity stratification of near-surface water masses as in the modern Arctic Ocean.

• Gaina, Carmen; Jakobsson, Martin; Straume, Eivind Olavson; Timmermans, Mary-Louise; Boggild, Kai & Bünz, Stefan [Vis alle 8 forfattere av denne artikkelen] (2025). Arctic Ocean bathymetry and its connections to tectonics, oceanography and climate. Nature Reviews Earth & Environment. 6, s. 211–227. doi: 10.1038/s43017-025-00647-0. Fulltekst i vitenarkiv Vis sammendrag

  For at least the past 50 million years, the Arctic region has had a major role in regulating global climate regimes and their variations through time. In this Review, we discuss the role of the Arctic oceanic basin and its complex bathymetry in controlling ocean circulation and marine cryosphere development. The spatial distribution and depth of various seafloor features, such as ocean gateways, submarine plateaus and continental shelves, influence the pathways of ocean currents, both today and in the past. The Arctic Ocean was an enclosed basin until the Early Eocene (56–48 million years ago), when the Eurasian Basin started to form and a shallow sea connected the Arctic to the Tethys Ocean. The connections with the North Atlantic and the global ocean through shallow and deep gateways prompted the transition from a global greenhouse to icehouse climate. However, the Arctic Ocean remains underexplored, as less than one-quarter of its seafloor is mapped in detail. Future integrated geoscience research, modern bathymetric mapping technology and active international programmes are needed to close these data gaps

• Senger, Kim; Ammerlaan, Fenna; Betlem, Peter; Brönner, Marco; Dumais, Marie-Andrée & Gellein, Jomar [Vis alle 20 forfattere av denne artikkelen] (2025). Crustal Heterogeneity Onshore Central Spitsbergen: Insights From New Gravity and Vintage Geophysical Data. Geochemistry Geophysics Geosystems. 26(1). doi: 10.1029/2024GC011563. Fulltekst i vitenarkiv Vis sammendrag

  Gravity data provide constraints on lateral subsurface density variations and thus provide crucial insights into the geological evolution of the region. Previously, gravity data from the Norwegian Arctic archipelago of Svalbard comprised an onshore regional gravity database with coarse station spacing of 2–20 km, offshore gravity profiles acquired in some fjords, airborne gravity, and satellite altimetry. The sparse regional point-based onshore coverage hampered the direct integration of gravity data with seismic profiles acquired onshore Svalbard in the late 1980s and early 1990s. In April 2022, we acquired gravity data at 260 new stations along seven profiles from western to eastern Spitsbergen, with a cumulative length of 329 km. The profiles were acquired directly along selected seismic profiles and provide much closer station spacing (0.5–2 km) compared to the regional inland grid (2–20 km) acquired in the late 1980s (total number of onshore stations: 1,037). Having processed the data, we compared the first-order density trends of our new data with the legacy regional grid. The new gravity data are consistent with the regional data, imaging a gravity low in the western part of the area underlying a foreland basin and a gravity high in the northwestern part of the area likely associated with a basement high or denser basement. We compare the new and vintage gravity using maps and profiles, linked to the known major tectonic features such as major basinal axes and fault zones, as well as other geophysical data sets including seismics and magnetics

• Belosa, Lea; Callegaro, Sara; Meyzen, Christine M; Gaina, Carmen; Polteau, Stephane & Bizimis, Michael [Vis alle 7 forfattere av denne artikkelen] (2024). Deep Mantle Component and Continental Crust Remobilization in the Source of Vesteris Seamount, East Greenland Margin. Geochemistry Geophysics Geosystems. 25(1). doi: 10.1029/2023GC011196. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Vesteris Seamount is a large Quaternary intraplate submarine volcano in the SW Greenland Sea, about 1,000 km NE of Iceland and 300 km NW of the Mohn's spreading ridge, whose mode of formation remains unsolved. We present geochemical data for new samples dredged from the Vesteris edifice, including major, trace elements and Sr‐Nd‐Pb‐Hf isotopes. The isotopic characteristics of the alkaline lavas, covering the basanite/tephrite to benmoreite range, indicate the involvement of depleted and enriched mantle components. The source is dominated by the depleted mantle (85%–90%) and a deep enriched component possibly supplied by the Iceland Plume (IP) (10%–15%). Additional source enrichment was due to recycled crust and sub‐continental lithospheric mantle, as suggested by Hf isotopes (0.283147 ± 0.000005) measured for the first time in Vesteris lavas and by a decoupling in Pb isotopes evidenced by relatively low‐radiogenic 207 Pb/ 204 Pb (15.510) and high‐radiogenic 208 Pb/ 204 Pb (38.554) with respect to the Northern Hemisphere Reference Line. We interpret the geochemical results using existing knowledge about the regional lithospheric and upper mantle structure. Our findings suggest that a deep (ca. 420–320 km) mantle anomaly, with seismological characteristics of the Iceland mantle plume, extends from East Greenland to the north of Jan Mayen Fracture Zone. The regional lithospheric thinning toward the Greenland Basin enabled the melting events that produced the Vesteris seamount. This lateral NNE‐directed flow lobe of the Iceland plume may have carved and transferred enriched components from the continental lithospheric margin of Greenland north of Scoresby Sund toward the Vesteris source.

• Janocha, Julian; Grundvåg, Sten-Andreas & Stockli, Daniel (2024). The Upper Devonian to Lower Carboniferous Billefjorden Group on Bjørnøya, Svalbard, and Its North-Eastern Greenlandic Provenance. Basin Research. ISSN 0950-091X. 36(6). doi: 10.1111/bre.70009. Fulltekst i vitenarkiv Vis sammendrag

  In this contribution, we document changes in detrital zircon ages in the upper Devonian (Famennian) to lower Carboniferous (Mississippian) Billefjorden Group on Bjørnøya, the southernmost island of Svalbard. This alluvial, coal-bearing clastic succession is widely distributed across the archipelago and the Barents Shelf. The sediments were deposited in subsidence-induced lowlands that formed just after regional post-Caledonian collapse-related extension, which created the classical ‘Old Red Sandstone’ basins during the Devonian, and prior to localised rift-basin development in the middle Carboniferous (Serpukhovian–Moscovian). Moreover, the succession is little affected by Ellesmerian compressional deformation, which occurred in the latest Devonian. However, little is known of the provenance and regional sediment routing in this tectonically transitional period between the post-Caledonian structuring events in the Devonian and the middle Carboniferous rifting. It has previously been invoked that a regional fault running parallel to the western Barents Shelf margin, the West Bjørnøya Fault, controlled sedimentation in the area. Here, we combine detrital zircon U–Pb ages and sedimentological data to investigate stratigraphic provenance variations and test whether tectonics controlled deposition of the Billefjorden Group on Bjørnøya. Sedimentological investigations demonstrate changes in fluvial style with intercalations between successions dominated by meandering channel fills and abundant overbank fines to sandstone-dominated sheet-like successions of braided stream origin. Palaeocurrent data show that two competing drainage directions accompany the changes in fluvial architecture. Northeasterly transport directions, recorded in the braided stream deposits, indicate possible fault-transverse drainage. The detrital zircon content in these deposits indicates sourcing from Caledonian terranes in Northeast Greenland. Northwest-oriented transport directions, measured in the meandering channel deposits, are inferred to represent axially positioned drainage systems. These may have been sourced from either Northeast Greenland, a more localised source, or Baltica. The latter would require long-distance sourcing, which, given the tectonic setting of the region, seems unlikely. Although our sedimentological observations point to syn-tectonic deposition, this is not clearly captured in the detrital zircon data, suggesting a common source for the Late Devonian–Mississippian fluvial systems of Bjørnøya. Thus, combined with previously published provenance data from Svalbard and Greenland, we demonstrate that the East Greenland Caledonides formed a long-lived and significant source area which provided sediments to nearby basins from the Devonian to the Early Cretaceous

• Senger, Kim; Shephard, Grace; Ammerlaan, Fenna; Anfinson, Owen; Audet, Pascal & Coakley, Bernard [Vis alle 20 forfattere av denne artikkelen] (2024). Arctic Tectonics and Volcanism: a multi-scale, multi-disciplinary educational approach. Geoscience Communication. ISSN 2569-7102. 7(4), s. 267–295. doi: 10.5194/gc-7-267-2024. Fulltekst i vitenarkiv Vis sammendrag

  Geologically, the Arctic is one of the least-explored regions of Earth. Obtaining data in the high Arctic is logistically, economically, and environmentally expensive, but the township of Longyearbyen (population of 2617 as of 2024) at 78° N represents a relatively easily accessible gateway to Arctic geology and is home to The University Centre in Svalbard (UNIS). These unique factors provide a foundation from which to teach and explore Arctic geology via the classroom, the laboratory, and the field. UNIS was founded in 1993 as the Norwegian “field university”, offering field-based courses in Arctic geology, geophysics, biology, and technology to students from Norway and abroad. In this contribution, we present one of the educational components of the international collaboration project NOR-R-AM (a Norwegian-Russian-North American collaboration in Arctic research and collaboration, titled Changes at the Top of the World through Volcanism and Plate Tectonics) which ran from 2017 to 2024. One of the key deliverables of NOR-R-AM was a new graduate (Master's and PhD-level) course called Arctic Tectonics and Volcanism that we have established and taught annually at UNIS since 2018 and detail herein. The course's main objective is to teach the complex geological evolution of the Arctic from the Devonian period (∼ 420 million years ago, Ma) to the present day through integrating multi-scale datasets and a broad range of geoscientific disciplines. We outline the course itself before presenting student perspectives based on both an anonymous questionnaire (n=27) and in-depth perceptions of four selected students. The course, with an annual intake of up to 20 MSc and PhD students, is held over a 6-week period, typically in spring or autumn. The course comprises modules on field and polar safety, Svalbard/Barents Sea geology, wider Arctic geology, plate tectonics, mantle dynamics, geo- and thermochronology, and geochemistry of igneous systems. A field component, which in some years included an overnight expedition, provides an opportunity to appreciate Arctic geology and gather field observations and data. Digital outcrop models, photospheres, and tectonic plate reconstructions provide complementary state-of-the-art data visualization tools in the classroom and facilitate efficient fieldwork through pre-fieldwork preparation and post-fieldwork quantitative analyses. The course assessment is centred around an individual research project that is presented orally and in a short and impactful Geology journal-style article. Considering the complex subject and the diversity of students' backgrounds and level of geological knowledge before the course, the student experiences during this course demonstrate that the multi-disciplinary, multi-lecturer field-and-classroom teaching is efficient and increases their motivation to explore Arctic science.

Se alle arbeider i NVA