Snorre Olaussen

• Senger, Kim; Ammerlaan, Fenna; Betlem, Peter; Gaina, Carmen; Galland, Olivier & Grundvåg, Sten-Andreas [Vis alle 21 forfattere av denne artikkelen] (2026). A Field Guide to the High Arctic Large Igneous Province in and Around Isfjorden, Svalbard. Tektonika. 3(2), s. 176–216. doi: https:/tektonika.online/index.php/home/article/view/124/197. Fulltekst i vitenarkiv Vis sammendrag

  The High Arctic Large Igneous Province (HALIP) is a major tectono-magmatic element that affected large parts of the Arctic during the Cretaceous (magmatism occurred from 126 to 78 million years ago [Ma]). In Svalbard, HALIP intrusive and extrusive rocks are grouped and classified as the Diabasodden Suite. Sills and dykes are present throughout Svalbard, emplaced in units stratigraphically ranging from crystalline basement to Jurassic-Cretaceous siliciclastics. Time-equivalent lava flows are exposed on Kong Karls Land in eastern Svalbard. In this contribution, we firstly define and introduce major features of the circum-Arctic HALIP. Secondly, we zoom into Svalbard where we document and summarize the attributes of HALIP outcrops (i.e., the Diabasodden Suite) located in and around Isfjorden, the most accessible location that is reachable on day trips using boats from Longyearbyen. For each of the 15 sites we focus on specific aspects of HALIP characterization, including geochronology, geochemistry and geometry of volcanic and intrusive rocks. We complement field descriptions of the sites with digital geoscientific data, including digital outcrop models and photospheres. Finally, we synthesize the Isfjorden study area in the context of data and knowledge gaps for the HALIP in general. We hope that this contribution will stimulate further HALIP research in Isfjorden and beyond.

• 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

• Smyrak-Sikora, Aleksandra; Betlem, Peter; Engelschiøn, Victoria Sjøholt; Foster, William J.; Grundvåg, Sten-Andreas & Jelby, Mads Engholm [Vis alle 26 forfattere av denne artikkelen] (2025). Phanerozoic paleoenvironmental and paleoclimatic evolution in Svalbard. Climate of the Past. ISSN 1814-9324. 21(11), s. 2133–2187. doi: 10.5194/cp-21-2133-2025. Fulltekst i vitenarkiv Vis sammendrag

  Sedimentary rocks can provide information about the Earth paleoenvironment and are studied extensively to understand the causes and consequences of global climate changes in deep time. They facilitate long-time perspectives that constrain climate models and provide analogues for how Earth systems may respond to, and recover from, intervals of profound environmental change, including projected anthropogenic change. The Norwegian Svalbard archipelago offers an extensive Phanerozoic stratigraphic record that reflects the geological evolution of the northern flanks of continental assemblages that include Laurentia, Eurasia, and Pangea. Svalbard's Phanerozoic sedimentary and paleoclimatic archive is controlled largely by Svalbard's overall northward plate-tectonic motion from equatorial to high latitudes but also by regional to local formation of topography and basins in response to long-term plate reorganization, as well as the near- and far-field influence of large igneous province activity on the tectono-stratigraphic and paleoclimatic development. Various sedimentary and geochemical proxies, such as bentonite beds and carbon isotope excursions associated with the far-reaching environmental effects of the Siberian Traps, the High Arctic Large Igneous Province, and the North Atlantic Igneous Province, are present in Svalbard's near complete geological record. As such, Svalbard is unique in that these and numerous other global environmental perturbations are recorded within a relatively restricted study area, with most of the key events preserved and recorded in easily accessible drill cores and well-exposed outcrop sections. Here we review deep-time paleoenvironmental and paleoclimate research in Svalbard by summarizing 148 peer-reviewed scientific articles. The review builds on the well-established tectono-stratigraphic and lithostratigraphic framework, as well as state-of-the art environmental reconstructions, to provide insights into the Earth system during the Phanerozoic northward drift of Svalbard and the many major biotic crises in the geological past. We focus on globally significant events including (i) the expansion of Devonian vegetation, (ii) the Carboniferous–Permian response to icehouse conditions during the Late Paleozoic Ice Age (LPIA), (iii) the End-Permian Mass Extinction (EPME) and the subsequent Triassic recovery, the (iv) Carnian Pluvial Episode, (v) Jurassic–Early Cretaceous climate perturbations including the Volgian Isotopic Carbon Excursion (VOICE) and the Aptian Ocean Anoxic Event 1a (OAE1a), and (vi) the Paleocene–Eocene Thermal Maximum (PETM). We present and synthesize existing core and outcrop data that preserve biological and geochemical proxies and climate-sensitive sedimentary facies that reflect environmental change in terrestrial and marine settings. Finally, we discuss the Phanerozoic climate recorded in Svalbard and its role in providing high-latitude calibration points for several global paleoclimate events to provide a higher-latitude perspective to complement the dominance of mid- and low-latitude locations and datasets in the literature.

• Senger, Kim; Ammerlaan, Fenna; Betlem, Peter; Dumais, Marie-Andrée; Eagles, Graeme & Foster, William [Vis alle 29 forfattere av denne artikkelen] (2025). Geology of Svalbard: Deep-time and Deep-Earth (SVALGEOL). I Neuber, R.; Łupikasza, E.; Hübner, C. & Holmén, K. (Red.), The State of Environmental Science in Svalbard – an annual report. Svalbard Integrated Arctic Earth Observing System. ISSN 9788293871149. s. 52–83. doi: 10.5281/zenodo.14425478. Fulltekst i vitenarkiv Vis sammendrag

  Geology is omnipresent in Svalbard, defining among other parameters the location of all major settlements. The SVALGEOL chapter provides an overview of the geology of Svalbard, and how it influences local and global society. We briefly describe the history of geological exploration and mapping of Svalbard, before outlining the various data sets geoscientists use in their work. We then focus on two key aspects of geology: the study of “deep-time” (i.e., rocks older than 2.58 million years; the pre-Quaternary period) and the study of “deep-Earth” (i.e., integration of data from Earth’s surface to the interior). By investigating the Earth System at the scale of millions to billions of years, geologists can decipher how the global climate has varied through time. Furthermore, studying different proxies allows us to investigate the processes linking the geosphere with the biosphere (e.g., evolution of life, recovery following mass extinctions). By using field and various geophysical data, geologists can understand the properties of the Earth from its surface to its core, and the processes causing them. Furthermore, by coupling deep, shallow and surface observations with a time component, geoscientists can characterise the underlying processes that also influence society (e.g., natural gas emissions, permafrost development, geothermal potential, earthquakes)

• 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

• Senger, Kim; Betlem, Peter; Braathen, Alvar; Olaussen, Snorre & Sand, Gunnar (2025). Longyearbyen CO2 lab project — from a vision of a CO2-neutral Svalbard to a geoscience data eldorado. Arctic Science. ISSN 2368-7460. 11, s. 1–26. doi: 10.1139/as-2024-0019. Fulltekst i vitenarkiv Vis sammendrag

  The Longyearbyen CO2 lab project was initiated in 2006 by the University Centre in Svalbard (UNIS) to establish whether subsurface storage of locally produced CO2 is feasible. Over a decade of drilling operations and geoscientific research concluded that the subsurface was suitable for storing the CO2 generated from the local power plant. The geological ingredients for successful CO2 storage are in place, comprising a ca. 300 m thick, sandstone-dominated reservoir rock capped by an impermeable mudstone-dominated succession. No CO2 was ever injected for storage in Svalbard for economic and political reasons. However, the project generated a wealth of new data, some of which proved critical for studies related to CO2 storage elsewhere. The data were also key to the characterization of fluid flow and geothermal potential in Svalbard, deciphering past climatic changes, unravelling past tectonic events, some of relevance for understanding the plate tectonic evolution of the Arctic, as well as updating the global geological timescale. In this contribution, we briefly outline the history and main achievements of the Longyearbyen CO2 lab project, before describing, categorizing and openly sharing the publicly available data from the project, including peer-reviewed publications (123 so far) and theses (18 PhD and 34 MSc).

• Dahlin, Anders; Blinkenberg, Kasper Høj; Braathen, Alvar; Olaussen, Snorre; Senger, Kim & Smyrak-Sikora, Aleksandra Anna [Vis alle 7 forfattere av denne artikkelen] (2024). Late syn-rift to early post-rift basin fill dynamics of a mixed siliciclastic-carbonate succession banked to a basement high, Hornsund, southwestern Spitsbergen, Arctic Norway. Basin Research. ISSN 0950-091X. 36(4). doi: 10.1111/bre.12880. Fulltekst i vitenarkiv Vis sammendrag

  The transition from syn-rift to post-rift sedimentation in rift basins is difficult to characterize in terms of stratigraphic architecture and dominating control on sedimentation, due to decreasing tectonic activity interplaying with regional subsidence, eustatic sea level changes, and differential compaction of underlying syn-rift sediments. Our case study of the Late Palaeozoic Inner Hornsund Fault Zone targets late syn-rift strata recorded in the (?Pennsylvanian – ?lower Permian) Treskelodden Formation in Hornsund, southern Spitsbergen, representing a mixed siliciclastic-carbonate succession, with siliciclastics primarily sourced from the adjacent Sørkapp-Hornsund High. We document local scale (<10 km) facies variability, sequence stratigraphy, and evolution of a succession deposited along a flank of the structural high during the late syn-rift stage. We observe that during the transition towards rift termination (glacio-)eustatic sea level changes and overall regional flooding became a more prominent forcing factor controlling sedimentation. Our dataset includes sedimentary logs, microfacies analysis, and high-resolution digital outcrop models. We identify four progressively backstepping stratigraphic sequences, reflecting an evolution from (1) terrestrial siliciclastics through (2–3) nearshore mixed siliciclastic–carbonates, to (4) carbonate ramp deposits. On the small scale (<5 m) the internal sediment cyclicity of the succession was formed by autogenic processes, particularly the changing rate of sediment input from the southwestern source area (the uplifted Sørkapp-Hornsund basement high). On the larger scale (10s of m), the importance of glacio-eustatic sea-level changes, driven by waxing and waning of ice caps in the southern hemisphere (Gondwana), increased as the rift-related tectonics decreased. The interdisciplinary methods used in this study provide new knowledge of the Middle Pennsylvanian to Permian depositional evolution in southern Spitsbergen, besides a novel framework for comparison to adjacent basins in the region and similar basins elsewhere.

• Park, Juni; Stein, Holly Jayne; Hannah, Judith Louise; Georgiev, Svetoslav; Hammer, Øyvind & Olaussen, Snorre (2024). Paleoenvironment in the circum-arctic region from the Middle Jurassic to Early Cretaceous: Trace element and stable isotope geochemistry of the Agardhfjellet Formation, Svalbard. Palaeogeography, Palaeoclimatology, Palaeoecology. ISSN 0031-0182. 649. doi: 10.1016/j.palaeo.2024.112333. Fulltekst i vitenarkiv
• Jelby, Mads Engholm; Grundvåg, Sten-Andreas; Sliwinska, Kasia K.; Alsen, Peter; Vickers, Madeleine Larissa & Olaussen, Snorre [Vis alle 7 forfattere av denne artikkelen] (2024). Lower Cretaceous holostratigraphy in Svalbard: the Arctic key piece of the Boreal basin puzzle. Geological Society Special Publication. ISSN 0305-8719. 545(1), s. 325–371. doi: 10.1144/SP545-2023-177. Fulltekst i vitenarkiv Vis sammendrag

  Lower Cretaceous stratigraphy of the high palaeo-latitude Arctic-Boreal Realm is generally more poorly understood than its lower-latitude Tethyan counterpart, prohibiting regional correlations and evaluation of global climate dynamics during this important high-pCO2 period. In this paper, a holostratigraphic scheme and lithostratigraphic revision are presented for the Valanginian-lower Barremian, siliciclastic ramp succession of the Rurikfjellet Formation in Svalbard, drawn from synthesis of the latest published sedimentological, biostratigraphic, petrophysical, sequence stratigraphic, chemostratigraphic and chronostratigraphic results, supplemented by new measured sections from five localities. The offshore mudstone-dominated Wimanfjellet Member (Valanginian-lower Barremian) is retained, whereas three new members are defined according to their distinct geographic, sedimentological and stratigraphic characteristics: The Adventpynten Member (upper(?) Valanginian-lowermost upper Hauterivian) constitutes a thick, relatively localized succession of mass-transport deposits. The Kikutodden Member (Hauterivian-lower Barremian) is discarded and replaced by the northern Bohemanneset Member and southern Fotografryggen Member, representing respectively: heterogeneous prodelta to delta front deposits; and sandy offshore transition to shoreface deposits. The Rurikfjellet Formation records Valanginian-earliest late Hauterivian shoreline progradation followed by late Hauterivian-early Barremian shoreline retreat and flooding across a low-gradient ramp, which never experienced full regression into continental deposits within the extent of the present-day outcrop belt

• Smelror, Morten; Olaussen, Snorre; Dumais, Marie-Andrée; Grundvåg, Sten-Andreas & Abay, Tesfamariam Berhane (2023). Northern Svalbard Composite Tectono-Sedimentary Element. Geological Society of London Memoirs. ISSN 0435-4052. 57. doi: 10.1144/M57-2023-2. Fulltekst i vitenarkiv Vis sammendrag

  The Northern Svalbard Composite Tectono-Sedimentary Element (CTSE) comprises Proterozoic, Early Paleozoic, and Devonian sedimentary rocks preserved in northern Svalbard and on the adjacent shelf margin. Here, the sedimentary strata of the CTSE are preserved between complexes of metamorphic and crystalline basement rocks. The Northern Svalbard CTSE covers four main tectonostratigraphic elements: Tonian syn-rift, Neoproterozoic to Cambrian post-rift, Ordovician passive margin, and late Silurian?/Devonian syn-extensional basins. The oldest documented sedimentary strata are greywacke and shale deposited after the Greenvillian Orogeny and assumed to be younger than 980-960 Ma. The present CTSE further includes Cambrian-Ordovician sedimentary rocks in Ny-Friesland and Nordaustlandet, while the dominant part of the CTSE are continental Old Red Sandstone sediments of the late Silurian?/Early Devonian Red Bay and Siktefjellet groups and the Early-Late Devonian Andreé Land Group onshore northern Spitsbergen. Locally, the Cambrian-Ordovician formations contain petroleum source rocks with moderate total organic carbon contents and relatively high hydrogen index values, suggesting a good potential for oil generation. There are possible reservoirs, seals, and traps in some of the basins, but the CTSE generally holds a very limited potential as a petroleum province, particularly as the region is under strict environmental protection

• Rodes, Nil; Betlem, Peter; Senger, Kim; Römer, Miriam; Hodson, Andrew & Liira, Martin [Vis alle 12 forfattere av denne artikkelen] (2023). Active gas seepage in western Spitsbergen fjords, Svalbard archipelago: spatial extent and geological controls. Frontiers in Earth Science. 11. doi: 10.3389/feart.2023.1173477. Fulltekst i vitenarkiv Vis sammendrag

  This study presents the first systematic observations of active gas seepage from the seafloor in the main fjords of western Spitsbergen in the Svalbard archipelago. High-resolution acoustic water column data were acquired throughout two research cruises in August 2015 and June 2021. 883 gas flares have been identified and characterized in Isfjorden, and 115 gas flares in Van Mijenfjorden. The hydroacoustic data indicate active fluid migration into the water column. Interpretation of 1943 km of regional offshore 2D seismic profiles supplemented the water column and existing gas geochemical data by providing geological control on the distribution of source rocks and potential migration pathways for fluids. In the study area, bedrock architecture controls the fluid migration from deep source rocks. Faults, high permeability layers, heavily fractured units and igneous intrusions channel the gas seepage into the water column. The observations of gas seepage presented in this study are an important step towards the assessment of how near-shore seepage impacts upon the carbon budget of Svalbard fjords, which constitute a globally recognized early climate change warning system for the High Arctic.

• Senger, Kim; Nuus, Matthijs Hendrik; Balling, Niels; Betlem, Peter; Birchall, Thomas & Christiansen, Hanne H [Vis alle 17 forfattere av denne artikkelen] (2023). The subsurface thermal state of Svalbard and implications for geothermal potential. Geothermics. ISSN 0375-6505. 111. doi: 10.1016/j.geothermics.2023.102702. Fulltekst i vitenarkiv Vis sammendrag

  Svalbard is a High Arctic Archipelago at 74–81°N and 15–35 °E under the sovereignty of Norway. All settlements in Svalbard, including the capital of Longyearbyen (population 2400), currently have isolated energy systems with coal or diesel as the main energy source. Geothermal energy is considered as a possible alternative for electricity production, as a heat source in district heating systems or harnessed for heating and cooling using geothermal heat pump installations. In this contribution we present the until now fragmented data sets relevant to characterize and assess the geothermal potential of Svalbard. Data sets include petroleum and deep research boreholes drilled onshore Svalbard, 14 of which have recorded subsurface temperature data at depths below 200 m. Geothermal gradients on Spitsbergen vary from 24 °C/km in the west to 55 °C/km in the south-east, with an average of 33 °C/km. Four deep research boreholes were fully cored and analyzed for thermal conductivity. These analyses were complemented by thermal conductivity calculated from wireline logs in selected boreholes and four measurements on outcrop samples. 1D heat flow modelling on five boreholes calibrated with the measured thermal conductivities offers insights into heat transfer through the heterogeneous sedimentary succession. Offshore petroleum boreholes in the south-western Barents Sea and marine heat flow stations around Svalbard provide a regional framework for discussing spatial variation in heat flow onshore Svalbard, with emphasis on the effects of erosion and deposition on the thermal regime. We conclude that Svalbard's geology is well suited for geothermal exploration and potential production, though challenges related to permafrost, the presence of natural gas, heterogeneous reservoir quality and strongly lateral varying heat flow need to be adequately addressed prior to geothermal energy production. Specifically for Longyearbyen, high geothermal gradients of 40–43 °C/km in the nearest borehole (DH4) suggest promising sub-surface thermal conditions for further exploration of deep geothermal potential near the settlement.

• Birchall, Thomas; Jochmann, Malte Michel; Betlem, Peter; Senger, Kim; Hodson, Andrew & Olaussen, Snorre (2023). Permafrost trapped natural gas in Svalbard, Norway. Frontiers in Earth Science. 11, s. 1–23. doi: 10.3389/feart.2023.1277027. Fulltekst i vitenarkiv Vis sammendrag

  Permafrost is widespread in the High Arctic, including the Norwegian archipelago of Svalbard. The uppermost permafrost intervals have been well studied, but the processes at its base and the impacts of the underlying geology have been largely overlooked. More than a century of coal, hydrocarbon, and scientific drilling through the permafrost in Svalbard shows that accumulations of natural gas trapped at the base of permafrost are common. These accumulations exist in several stratigraphic intervals throughout Svalbard and show both thermogenic and biogenic origins. The gas, combined with the relatively young permafrost age, is evidence of ongoing gas migration throughout Svalbard. The accumulation sizes are uncertain, but one case demonstrably produced several million cubic metres of gas over 8 years. Heavier gas encountered in two boreholes on Hopen may be situated in the gas hydrate stability zone. While permafrost is demonstrably ice-saturated and acting as seal to gas in lowland areas, in the highlands permafrost is more complex and often dry and permeable. Svalbard shares a similar geological and glacial history with much of the Circum-Arctic, suggesting that sub-permafrost gas accumulations are regionally common. With permafrost thawing in the Arctic, there is a risk that the impacts of releasing of methane trapped beneath permafrost will lead to positive climatic feedback effects.

• Olaussen, Snorre; Grundvåg, Sten-Andreas; Senger, Kim; Anell, Ingrid; Betlem, Peter & Birchall, Thomas [Vis alle 15 forfattere av denne artikkelen] (2023). Svalbard Composite Tectono-Sedimentary Element, Barents Sea”. Geological Society of London Memoirs. ISSN 0435-4052. 57. doi: 10.1144/M57-2021-36. Fulltekst i vitenarkiv Vis sammendrag

  The Svalbard Composite Tectono-Sedimentary Element (SCTSE) is located on the northwestern corner of the Barents Shelf and comprises a Carboniferous–Pleistocene sedimentary succession. Due to Cenozoic uplift, the succession is subaerially exposed in the Svalbard archipelago. The oldest parts of the succession consist of Carboniferous–Permian mixed siliciclastic, carbonate and evaporite, and spiculitic sediments that developed during multiple phases of extension. The majority of the Mesozoic succession is composed of siliciclastic deposits formed in sag basins and continental platforms. Episodes of Late Jurassic and Early Cretaceous contraction are evident in the eastern part of thearchipelago and in nearby offshore areas. Differential uplift related to the opening of the Amerasian Basin and the Cretaceous emplacement of the High Arctic Large Igneous Province created a major hiatus spanning from the Late Cretaceous and early Danian throughout the SvalbardCTSE. The West Spitsbergen Fold and Thrust Belt and the associated foreland basin in central Spitsbergen (Central Tertiary Basin) formed as a response to the Eurekan Orogeny and the progressive northward opening of the North Atlantic during the Paleogene. This event was followed by the formation of yet another major hiatus spanning the Oligocene–Pliocene. Multiple reservoir and source-rock units exposed in Svalbardprovide analogues to the prolific offshore acreages in the SW Barents Sea, and are important for the de-risking of plays and prospects. However, the archipelago itself is regarded as a high-risk acreage for petroleum exploration. This is due to Paleogene contraction and late Neogene uplift of the western and central parts in particular. There is an absence of mature source rocks in the east, and the entire region is subjected to strict environmental protection

• Park, Junhee; Stein, Holly Jayne; Hannah, Judith Louise; Georgiev, Svetoslav V.; Hammer, Øyvind & Olaussen, Snorre (2023). Re-Os geochronology of the Middle to Upper Jurassic marine black shales in the Agardhfjellet Formation, Central Spitsbergen, Svalbard: A cornerstone for global faunal correlation and Os isotopic change. Palaeogeography, Palaeoclimatology, Palaeoecology. ISSN 0031-0182. 633. doi: 10.1016/j.palaeo.2023.111878. Fulltekst i vitenarkiv
• Klausen, Tore Grane; Rismyhr, Bjarte; Müller, Reidar & Olaussen, Snorre (2022). Changing provenance and stratigraphic signatures across the Triassic–Jurassic boundary in eastern Spitsbergen and the subsurface Barents Sea. Norwegian Journal of Geology. ISSN 2387-5844. 102. doi: 10.17850/njg102-2-1. Fulltekst i vitenarkiv Vis sammendrag

  A change to more sandstone dominated deposits and increasing condensation across the Triassic–Jurassic boundary is generally associated with improved reservoir quality in the Barents Sea. However, spatial and temporal changes in reservoir quality in this interval shows that the composition of the sediment source, immature sedimentary rocks supplied from the east or recycled in the basin in contrast to mature arenites to the south and west, affect the reservoir quality. The regional distribution of the different sources is best constrained in the southwestern part of the Barents Sea, and hitherto there has been no direct comparison between the zircon signature in outcrop analogues and their subsurface equivalents. In this study we evaluate the stratigraphic development of formations across the Triassic–Jurassic boundary in the Barents Sea and eastern Spitsbergen to compare their provenance signatures. By coupling outcrop and core data, we tie together the regional tectono-stratigraphic evolution of this important reservoir interval and relate the variable degree of sediment reworking with the relative distribution of immature Triassic sedimentary rocks across the basin. Results show higher degrees of erosion and reworking in Spitsbergen compared to the Barents Sea, consistent with local variations in the forebulge province of Novaya Zemlya observed in the subsurface. Provenance samples from Spitsbergen also record the same change in signature as in the subsurface Barents Sea. However, mature sediments are mixed with immature sediments later in Spitsbergen, indicating a latency in progradation from mature source areas which favour southern provenance areas in Fennoscandia as opposed to Greenland. Presence of young detrital zircon grains with similar Norian ages are recorded in the Upper Triassic strata both in the southernmost Barents Sea and on Spitsbergen, suggesting that a sediment source was active east of the basin and supplied sediment uniformly to the entire basin during the late Triassic.

• Abay, Tesfamariam Berhane; Karlsen, Dag Arild; Olaussen, Snorre; Pedersen, Jon Halvard & Hanken, Nils-Martin (2022). Organic geochemistry of Cambro-Ordovician succession of Ny Friesland, Svalbard, High Arctic Norway: Petroleum generation potential and bulk geochemical properties. Journal of Petroleum Science and Engineering. ISSN 0920-4105. 218. doi: 10.1016/j.petrol.2022.111033. Fulltekst i vitenarkiv Vis sammendrag

  Lower Paleozoic source rock (SR) characteristics and paleo-depositional environments are not well understood in the Barents Sea region. Organic and inorganic geochemical analyses of 17 carbonaceous samples from the Lower Cambrian Tokammane Formation, the Lower to Middle Ordovician Kirtonryggen and Valhallfonna formations in Ny Friesland, north-east Spitsbergen, show that there is a striking difference in petroleum generation potential and bulk geochemical properties between the Cambrian and Ordovician samples, and also within the Ordovician samples. TOC contents of <0.20 wt% for the Lower Cambrian Tokammane Formation samples indicate poor source rock richness. TOC contents in the range between 0.3 and 2.1 wt% and HI values between 123 and 424 mg HC/g TOC for the Valhallfonna and Kirtonryggen formation samples suggest significant variation in remaining petroleum generation potential with oil-prone (Type II) to mixed oil- and gas-prone (Type II/III) kerogen. Source rock maturity parameters such as Tmax (range 435–449 °C) and production indices for most Ordovician samples suggest relatively uniform maturity levels, ranging from the early-, to the peak-, of the oil generation window (i.e. ca. 0.70–0.85% Ro). This maturity level could have significant implication on the original petroleum potential assuming early generation from carbonate source rocks. Bulk carbon isotope data show that the Lower Cambrian Tokammane Formation samples are heavier (δ13C range from −28.4 to −28.8‰) than the Lower to Middle Ordovician Valhallfonna Formation samples (δ13C range from −29.7 to −30.9‰). The differences in the source rock richness and kerogen type within the Ordovician samples are attributed to organic facies variation. Tentatively, three categories of source rock organic facies (B, BC and C) are supported based on assumed-initial hydrogen index values for the Ordovician samples. The reliability of the indicated organic facies could be supported by addition of biomarker data from bitumen extracts. To our knowledge, this is the first study revealing the existence of a potential Lower Paleozoic source rocks in this part of the High Arctic, and this facies may also exist on the continental shelf to the north and NE.

• Müller, Reidar; Klausen, T.G.; Line, L.H.; Hafeez, A.; Planke, Sverre & Eide, F. [Vis alle 10 forfattere av denne artikkelen] (2022). Tectonostratigraphic development of the Upper Triassic to Middle Jurassic in the Hoop Area, Barents Sea: Implications for understanding ultra-condensed reservoir units. Marine and Petroleum Geology. ISSN 0264-8172. 145. doi: 10.1016/j.marpetgeo.2022.105787. Fulltekst i vitenarkiv Vis sammendrag

  The most prolific reservoir intervals in the Barents Sea are found in the Upper Triassic to Middle Jurassic Realgrunnen Subgroup, deposited during a major change in the structural evolution of the basin which greatly influenced its development and distribution. The effects are evident in one of the petroleum provinces in the SW Barents Sea, the Hoop Area. Due to the condensed nature of the succession, the tectonostratigraphic evolution has been enigmatic. We use a range of different methods and dataset, including high-resolution P-Cable seismic to determine the tectono-stratigraphic evolution of the succession. Results are important for exploration and production in the Hoop Area and beyond, but also for a broader understanding of how ultra-condensed successions might evolve during long periods of non-deposition and short bursts of deposition. Seven major phases of deposition and non-deposition/erosion are defined. Stage 1 represents fluvio-deltaic deposition in the Fruholmen Formation (Norian), followed by Stage 2 with significant truncation and non-deposition, lasting up to 35 million years. Deposition resumed with the shallow marine to fluvial Nordmela and Stø formations (Pliensbachian to Bajocian), which both encapsule long periods of erosion and non-deposition (stage 3–6). Stage 7 is represented by transgression and shelf deposition in the Fuglen Formation (Bathonian). The change from a high-accommodation setting with continuous and relatively high rate of accumulation in the Triassic, to a low-accommodation setting with episodic deposition and extensive sediment cannibalization in the Jurassic, resulted in cleaner sandstones with better reservoir properties. The low-accommodation setting also enabled coarse-graded detritus from hinterlands in Fennoscandia to prograde into distal part of the basin and more amalgamation of the sands during the Jurassic. Adversely, the low accommodation setting also caused a fragmented pattern of deposition and preservation that needs to be carefully considered in subsurface datasets, often with limited resolution.

• Lord, Gareth Steven; Mørk, Atle; Haugen, Turid; Boxaspen, Marit Ann; Husteli, Berit & Forsberg, Cathinka Schaanning [Vis alle 8 forfattere av denne artikkelen] (2022). Stratigraphy and palaeosol profiles of the Upper Triassic Isfjorden Member, Svalbard. Norwegian Journal of Geology. ISSN 2387-5844. 102. doi: 10.17850/njg102-4-02. Fulltekst i vitenarkiv Vis sammendrag

  The Isfjorden Member forms the upper part of the De Geerdalen Formation in Svalbard and is well exposed throughout central and eastern Spitsbergen, including the island of Wilhelmøya. We examine palaeosol profiles identified in the Isfjorden Member and compare these to profiles seen in the remainder of the De Geerdalen Formation. In addition, we address the nuances of the Isfjorden Member, its practicality as a stratigraphic interval and attempt to constrain the unit’s presence, as well as the nature of its lower boundary throughout outcrops in Svalbard. The Isfjorden Member is easily recognised by its conspicuous beds of alternating red and green coloured palaeosols, occasional caliche profiles and bivalve coquina beds. These beds have commonly been used to identify the unit in outcrop and we explore their relevance to the formal stratigraphic definition. The lower boundary is typically difficult to identify, especially when using the original definition; however, we find that placing it at the top of the last major sandstone in the De Geerdalen Formation is a practical solution. The boundary is conformable throughout Spitsbergen with no obvious erosion or break in sedimentation observed.The abundance, thickness and maturity of palaeosols increases upwards through the De Geerdalen Formation. Mature palaeosol and occasional caliche horizons are found to dominate within the Isfjorden Member. Immature palaeosols are in general constrained to the strata below. The position of palaeosols in relation to sedimentary successions is typically restricted to floodplain and interdistributary bay deposits, or atop upper shoreface deposits. The transition from immature palaeosols with common histosols to mature palaeosols and caliche reflects the development of the delta plain from a dynamic paralic setting to a morestable proximal system.

• Senger, Kim; Birchall, Thomas; Betlem, Peter; Ogata, Kei; Ohm, Sverre Ekrene & Olaussen, Snorre [Vis alle 7 forfattere av denne artikkelen] (2021). Resistivity of reservoir sandstones and organic rich shales on the Barents Shelf: Implications for interpreting CSEM data. Geoscience Frontiers (GSF). ISSN 1674-9871. 12(6), s. 1–17. doi: 10.1016/j.gsf.2020.08.007. Fulltekst i vitenarkiv Vis sammendrag

  Marine controlled source electromagnetic (CSEM) data have been utilized in the past decade during petroleum exploration of the Barents Shelf, particularly for de-risking the highly porous sandstone reservoirs of the Upper Triassic to Middle Jurassic Realgrunnen Subgroup. In this contribution we compare the resistivity response from CSEM data to resistivity from wireline logs in both water- and hydrocarbon-bearing wells. We show that there is a very good match between these types of data, particularly when reservoirs are shallow. CSEM data, however, only provide information on the subsurface resistivity. Careful, geology-driven interpretation of CSEM data is required to maximize the impact on exploration success. This is particularly important when quantifying the relative resistivity contribution of high-saturation hydrocarbon-bearing sandstone and that of the overlying cap rock. In the presented case the cap rock comprises predominantly organic rich Upper Jurassic–Early Cretaceous shales of the Hekkingen Formation (i.e. a regional source rock). The resistivity response of the reservoir and its cap rock become merged in CSEM data due to the transverse resistance equivalence principle. As a result of this, it is imperative to understand both the relative contributions from reservoir and cap rock, and the geological significance of any lateral resistivity variation in each of the units. In this contribution, we quantify the resistivity of organic rich mudstone, i.e. source rock, and reservoir sandstones, using 131 exploration boreholes from the Barents Shelf. The highest resistivity (>10,000 ​Ωm) is evident in the hydrocarbon-bearing Realgrunnen Subgroup which is reported from 48 boreholes, 43 of which are used for this study. Pay zone resistivity is primarily controlled by reservoir quality (i.e. porosity and shale fraction) and fluid phase (i.e. gas, oil and water saturation). In the investigated wells, the shale dominated Hekkingen Formation exhibits enhanced resistivity compared to the background (i.e. the underlying and overlying stratigraphy), though rarely exceeds 20 ​Ωm. Marine mudstones typically show good correlation between measured organic richness and resistivity/sonic velocity log signatures. We conclude that the resistivity contribution to the CSEM response from hydrocarbon-bearing sandstones outweighs that of the organic rich cap rocks

• Matysik, Michal; Stemmerik, Lars; Olaussen, Snorre; Rameil, Niels; Gianotten, Ingrid Piene & Brunstad, Harald (2021). Cherts, spiculites, and collapse breccias – Porosity generation in upper Permian reservoir rocks, Gohta discovery, Loppa High, south-western Barents Sea. Marine and Petroleum Geology. ISSN 0264-8172. 128. doi: 10.1016/j.marpetgeo.2021.105043. Fulltekst i vitenarkiv
• Yang, Zhang; Ogg, James G; Minguez, Daniel; Hounslow, Mark; Olaussen, Snorre & Gradstein, Felix M. [Vis alle 7 forfattere av denne artikkelen] (2021). Magnetostratigraphy of U-Pb–dated boreholes in Svalbard, Norway, implies that magnetochron M0r (a proposed Barremian-Aptian boundary marker) begins at 121.2 ± 0.4 Ma. Geology. ISSN 0091-7613. 49(6), s. 733–737. doi: 10.1130/G48591.1. Fulltekst i vitenarkiv
• Motta, Andres Felipe Cedeno; Ohm, Sverre Ekrene; Varela, Alejandro Escalona; Restrepo, Dora Luz Marin; Olaussen, Snorre & Demchuk, Thomas (2021). Upper Jurassic to Lower Cretaceous source rocks in the Norwegian Barents Sea, part II: Insights from open- and closed-system pyrolysis experiments. Marine and Petroleum Geology. ISSN 0264-8172. 134, s. 1–14. doi: 10.1016/j.marpetgeo.2021.105343. Fulltekst i vitenarkiv Vis sammendrag

  The petroleum generation potential of Upper Jurassic to Lower Cretaceous organic rich shales from the southwestern Barents Sea was evaluated using bulk and quantitative pyrolysis analysis. Fifteen thermally-immature samples from the Hekkingen Formation with differing organic facies, as defined by maceral composition, were subjected to total organic carbon, Rock-Eval pyrolysis, pyrolysis gas chromatography, bulk kinetics, and micro-scale sealed vessel pyrolysis analyses. The results were employed to characterize differences in source rock kerogens, gross petroleum type, and the compositional evolution of the generated fluids as well as their physical properties (i.e. gas to oil ratio, saturation pressure, and formation volume factor) as a function of increasing maturity. The investigated samples contain varying proportions of kerogen type II and III. Heterogeneities in the kerogen composition result in different orders of thermal stability, with the onset of petroleum generation predicted to occur over a high and broad temperature range from 123 °C to 144 °C (at 3.3C⁰/Ma). Reduced kerogen stability associated with elevated sulfur contents is only documented in a few samples. Most of the analyzed samples have the potential to generate low GOR oils of an intermediate to aromatic, low wax paraffinic-naphthenic-aromatic (P–N-A) composition and variable amounts of wet gas. Petroleums of similar compositional and physical properties are predicted to have been generated from the natural maturation sequence of various organic facies in thermally mature areas of the Hammerfest Basin and the Ringvassøy-Loppa High and Bjørnøyrenna fault complexes. Vitrinite-rich sources in the Fingerdjupet Sub-basin and the Troms-Finnmark Fault Complex have potential for gas and condensate generation.

• Motta, Andres Felipe Cedeno; Ohm, Sverre Ekrene; Varela, Alejandro Escalona; Restrepo, Dora Luz Marin; Olaussen, Snorre & Demchuk, Thomas (2021). Upper Jurassic to Lower Cretaceous source rocks in the Norwegian Barents Sea, part I: Organic geochemical, petrographic, and paleogeographic investigations. Marine and Petroleum Geology. ISSN 0264-8172. 134, s. 1–18. doi: 10.1016/j.marpetgeo.2021.105342. Fulltekst i vitenarkiv Vis sammendrag

  This study provides a subregional to regional characterization of organofacies changes within the two members of the Upper Jurassic to Lower Cretaceous Hekkingen Formation (i.e. Alge and Krill) by integrating geochemical and petrographic analysis with paleogeographic models. The gross kerogen composition of the Hekkingen Formation is dominated by terrestrial macerals. This preponderance of land-derived particles is more pronounced in the Krill Member than in the underlying Alge Member. There is a greater proportion of marine macerals within distal areas of the Hammerfest Basin and well 7218/1-S in the southern Bjørnøyrenna Fault Complex. This shift in the relative proportion of marine and terrestrial macerals is ascribed to changes in the location of the depositional sites with respect to the sources of the terrestrial materials. The Alge Member features the highest levels of total organic carbon (TOC ≥7 wt %), but the more discrete and organically poorer beds of the Krill Member still remain sufficiently rich to be considered petroleum source rocks (TOC ≥2 wt %). Hydrogen indices (HI) between 50 and 400 mg HC/g TOC recorded throughout the entire formation indicate that the kerogen within both members has similar oil and gas generation capabilities. These low to moderate HI values are indicative of immature Type III to II-III kerogens and are generally consistent with the high proportions of terrestrial macerals. Prior to thermal maturation, marine type II kerogens (i.e. ≤ 400 mgHC/gTOC) probably existed in the marine liptinite-rich rocks in the distal Hammerfest Basin and Bjørnøyrenna Fault Complex. At least three factors controlled the detected variability in geochemical parameters: dilution rates of organic matter, varying inputs of terrestrial versus marine organic matter, and the degree of preservation. The documented variability in organic-rich facies assists in reducing source rock risk in the study area, but also helps explorationists understand source rock distribution across other shelfal areas.

• Smyrak-Sikora, Aleksandra; Nicolaisen, Jakob; Braathen, Alvar; Johannessen, Erik P.; Olaussen, Snorre & Stemmerik, Lars (2021). Impact of growth faults on mixed siliciclastic-carbonate-evaporite deposits during rift climax and reorganisation—Billefjorden Trough, Svalbard, Norway. Basin Research. ISSN 0950-091X. 33(5), s. 2643–2674. doi: 10.1111/bre.12578. Fulltekst i vitenarkiv Vis sammendrag

  Fault-controlled mixed siliciclastic-carbonate-evaporite depositional systems exhibit distinct sensitivity to tectonic and eustatic controls that are expressed in the sedimentary architecture. In the Upper Carboniferous Billefjorden Trough (Svalbard, Norway), up to 2,000 m of a warm and arid climate syn-rift basin fill comprises such depositional systems, documented in this study with traditional field techniques supported by helicopter- and ground-based LIDAR models. The basin evolved from siliciclastics-dominated red beds and paralic units that filled a symmetrical basin, to a rift climax half-graben with alluvial fans entering the basin along relay ramps of the master fault zone (Billefjorden fault zone). Faults located in the hanging wall dip-slope prevented the progradation of coarser material to the eastern part of the basin. Later, structural reorganisation in the dipslope led to the cessation of easternmost faults with deformation focusing along one major lineament (Løvehovden fault zone) antithetic to the master fault zone. The basin subsidence became more symmetrical, with main central depocentre and shallower platforms near the basin flanks. Footwall anticlines from faults displacement gradients were sensitive to periodical exposure and recorded dissolution breccias and footwall synclines preserved evaporites coupled with shallow marine siliciclastic deposits. Concurrently, thick gypsum/anhydrite deposits in the basin centre reflect glacio-eustatic lowstands, whereas evenly thick carbonate deposition characterises highstands. While most analysis of syn-rift basin fill is based on siliciclastics deposits, we here demonstrate the complexity of tectonism versus eustatic sea level changes in a mixed carbonate-evaporite syn-rift deposits. Tectonic influence is ascribed to the deposition of alluvial fans that prograded from the master fault towards the basin centre. On the dipslope glacio-eustatic signals outperformed tectonic influence on deposition. Sea level lowstands promoted deposition of red sabkha mudstones and gypsum/anhydrite, salinas evaporites or dissolution breccias, interbedded with highstand carbonate beds.

• Senger, Kim; Betlem, Peter; Grundvåg, Sten-Andreas; Horota, Rafael Kenji; Buckley, Simon John & Smyrak-Sikora, Aleksandra [Vis alle 15 forfattere av denne artikkelen] (2021). Teaching with digital geology in the high Arctic: Opportunities and challenges. Geoscience Communication. ISSN 2569-7102. 4(3), s. 399–420. doi: 10.5194/gc-4-399-2021. Fulltekst i vitenarkiv Vis sammendrag

  The Covid-19 pandemic occurred at a time of major revolution in the geosciences – the era of digital geology. Digital outcrop models (DOMs) acquired from consumer drones, processed using user-friendly photogrammetric software and shared with the wider audience through online platforms are a cornerstone of this digital geological revolution. Integration of DOMs with other geoscientific data, such as geological maps, satellite imagery, terrain models, geophysical data and field observations, strengthens their application in both research and education. Teaching geology with digital tools advances students' learning experience by providing access to high-quality outcrops, enhancing visualization of 3D geological structures and improving data integration. Similarly, active use of DOMs to integrate new field observations will facilitate more effective fieldwork and quantitative research. From a student's perspective, georeferenced and scaled DOMs allow for an improved appreciation of scale and of 3D architecture, which is a major threshold concept in geoscientific education. DOMs allow us to bring geoscientists to the outcrops digitally, which is particularly important in view of the Covid-19 pandemic that restricts travel and thus direct access to outcrops. At the University Centre in Svalbard (UNIS), located at 78∘ N in Longyearbyen in Arctic Norway, DOMs are actively used even in non-pandemic years, as the summer field season is short and not overlapping with the Bachelor “Arctic Geology” course package held from January to June each year. In 2017, we at UNIS developed a new course (AG222 “Integrated Geological Methods: From Outcrop To Geomodel”) to encourage the use of emerging techniques like DOMs and data integration to solve authentic geoscientific challenges. In parallel, we have established the open-access Svalbox geoscientific portal, which forms the backbone of the AG222 course activities and provides easy access to a growing number of DOMs, 360∘ imagery, subsurface data and published geoscientific data from Svalbard. Considering the rapid onset of the Covid-19 pandemic, the Svalbox portal and the pre-Covid work on digital techniques in AG222 allowed us to rapidly adapt and fulfil at least some of the students' learning objectives during the pandemic. In this contribution, we provide an overview of the course development and share experiences from running the AG222 course and the Svalbox platform, both before and during the Covid-19 pandemic

• Tsikalas, Filippos; Blaich, Olav Antonio; Faleide, Jan Inge & Olaussen, Snorre (2021). Stappen High–Bjørnøya Tectono-Sedimentary Element, Barents Sea. Geological Society of London Memoirs. ISSN 0435-4052. 57. doi: 10.1144/M57-2016-24. Fulltekst i vitenarkiv
• Olaussen, Snorre; Braathen, Alvar; Senger, Kim & Braathen, Catherine (2021). Peer-reviewd publications, graduated PhD and MSc theses that iclude material from UNIS CO2 Lab from 2008 to 2020. Norwegian Journal of Geology. ISSN 2387-5844. 99(2), s. 371–376. doi: 10.17850/njg009. Fulltekst i vitenarkiv
• Large, David J.; Marshall, Chris; Jochmann, Malte Michel; Jensen, Maria; Spiro, Baruch F. & Olaussen, Snorre (2021). Time, Hydrologic Landscape, and the Long-Term Storage of Peatland Carbon in Sedimentary Basins. Journal of Geophysical Research (JGR): Earth Surface. ISSN 2169-9003. 126(3). doi: 10.1029/2020JF005762. Fulltekst i vitenarkiv
• Hodson, Andrew; Nowak, Aga; Hornum, Mikkel Toft; Senger, Kim; Redeker, Kelly Robert & Christiansen, Hanne H [Vis alle 12 forfattere av denne artikkelen] (2020). Sub-permafrost methane seepage from open-system pingos in Svalbard. The Cryosphere. ISSN 1994-0416. 14(11), s. 3829–3842. doi: 10.5194/tc-14-3829-2020. Fulltekst i vitenarkiv Vis sammendrag

  Methane release from beneath lowland permafrost represents an important uncertainty in the Arctic greenhouse gas budget. Our current knowledge is arguably best developed in settings where permafrost is being inundated by rising sea level, which means much of the methane is oxidised in the water column before it reaches the atmosphere. Here we provide a different process perspective that is appropriate for Arctic fjord valleys where local deglaciation causes isostatic uplift to out pace rising sea level. We describe how the uplift induces permafrost aggradation in former marine sediments, whose pressurisation results in methane escape directly to the atmosphere via groundwater springs. In Adventdalen, central Spitsbergen, we show how the springs are historic features responsible for the formation of open-system pingos and capable of discharging brackish waters enriched with high concentrations of mostly biogenic methane (average 18 mg L−1). Thermodynamic calculations show that the methane concentrations sometimes marginally exceed the solubility limit for methane in water at 0 ∘C (41 mg L−1). Year-round emissions from the pingos are described. During winter, rapid methane loss to the atmosphere occurs following outburst events from beneath an ice blister. During summer, highly variable emissions occur due to complex surface processes at the seepage point and its inundation by surface runoff. In spite of this complexity, our observations confirm that sub-permafrost methane migration deserves more attention for the improved forecasting of Arctic greenhouse gas emissions.

• Grundvåg, Sten-Andreas; Jelby, Mads Engholm; Olaussen, Snorre & Sliwinska, Kasia (2020). The role of shelf morphology on storm-bed variability and stratigraphic architecture, Lower Cretaceous, Svalbard. Sedimentology. ISSN 0037-0746. 68(1), s. 196–237. doi: 10.1111/sed.12791. Fulltekst i vitenarkiv Vis sammendrag

  The dominance of isotropic hummocky cross‐stratification, recording deposition solely by oscillatory flows, in many ancient storm‐dominated shoreface–shelf successions is enigmatic. Based on conventional sedimentological investigations, this study shows that storm deposits in three different and stratigraphically separated siliciclastic sediment wedges within the Lower Cretaceous succession in Svalbard record various depositional processes and principally contrasting sequence stratigraphic architectures. The lower wedge is characterized by low, but comparatively steeper, depositional dips than the middle and upper wedges, and records a change from storm‐dominated offshore transition – lower shoreface to storm‐dominated prodelta – distal delta front deposits. The occurrence of anisotropic hummocky cross‐stratification sandstone beds, scour‐and‐fill features of possible hyperpycnal‐flow origin, and wave‐modified turbidites within this part of the wedge suggests that the proximity to a fluvio‐deltaic system influenced the observed storm‐bed variability. The mudstone‐dominated part of the lower wedge records offshore shelf deposition below storm‐wave base. In the middle wedge, scours, gutter casts and anisotropic hummocky cross‐stratified storm beds occur in inferred distal settings in association with bathymetric steps situated across the platform break of retrogradationally stacked parasequences. These steps gave rise to localized, steeper‐gradient depositional dips which promoted the generation of basinward‐directed flows that occasionally scoured into the underlying seafloor. Storm‐wave and tidal current interaction promoted the development and migration of large‐scale, compound bedforms and smaller‐scale hummocky bedforms preserved as anisotropic hummocky cross‐stratification. The upper wedge consists of thick, seaward‐stepping successions of isotropic hummocky cross‐stratification‐bearing sandstone beds attributed to progradation across a shallow, gently dipping ramp‐type shelf. The associated distal facies are characterized by abundant lenticular, wave ripple cross‐laminated sandstone, suggesting that the basin floor was predominantly positioned above, but near, storm‐wave base. Consequently, shelf morphology and physiography, and the nature of the feeder system (for example, proximity to deltaic systems) are inferred to exert some control on storm‐bed variability and the resulting stratigraphic architecture

• Birchall, Thomas; Senger, Kim; Hornum, Mikkel Toft; Olaussen, Snorre & Braathen, Alvar (2020). Underpressure in the northern Barents shelf: Causes and implications for hydrocarbon exploration. American Association of Petroleum Geologists Bulletin. ISSN 0149-1423. 104(11), s. 2267–2295. doi: 10.1306/02272019146. Fulltekst i vitenarkiv Vis sammendrag

  The underexplored Barents shelf petroleum province is a globally unique example where naturally occurring underpressure is observed offshore and onshore. In the offshore parts of the northern Barents shelf, minor underpressure (up to 23 bar below hydrostatic pressure) is observed in the fault-bounded Mesozoic reservoirs of the Fingerdjupet subbasin. More severe (50 bar below hydrostatic pressure although irregular, occurrences of underpressure are encountered in the Triassic intervals of the neighboring Greater Hoop area. The abnormal pressures extend to the onshore archipelago of Svalbard, where pressures exceeding 60 bar below hydrostatic were encountered during drilling for a CO2 sequestration project. In Svalbard, reservoir pressures were constantly monitored over 3 yr, providing an insight into the reservoir behavior at unique time scales. The low-permeability (<2 md) reservoir in Svalbard is exposed some 15 km to the north of the drill site. Quantitative analysis with the apparent lack of a regional lateral seal suggests a geologically recent origin of underpressure. Evidence that the underpressure extends into the top seal provides further indication to the likely cause of underpressure. Similar to many global occurrences of underpressure in petroleum provinces, the Barents shelf has undergone severe uplift, most recently caused by deglaciation. Well data, outcrop observations, and isotope data combined with the area’s geological history indicate that glacial loading, unloading, and erosion, potentially with the aid of natural fractures, is the likely dominant underpressure-generating mechanism.

• Anell, Ingrid Margareta; Zuchuat, Valentin; Röhnert, A.D.; Smyrak-Sikora, Aleksandra; Buckley, Simon John & Lord, Gareth Steven [Vis alle 12 forfattere av denne artikkelen] (2020). Tidal amplification and along‐strike process variability in a mixed‐energy paralic system prograding onto a low accommodation shelf, Edgeøya, Svalbard. Basin Research. ISSN 0950-091X. s. 1–35. doi: 10.1111/bre.12482. Fulltekst i vitenarkiv Vis sammendrag

  The study describes the depositional development and sediment partitioning in a prograding paralic Triassic succession. The deposits are associated with the advance of large prism‐scale clinoforms across a shallower platform area. Approaching the platform, the limited accommodation and associated relative higher rates of deposition generated straighter clinoforms with lower foreset angles. The vertical restriction across the platform is interpreted to have amplified the tidal signature. Sediment was redistributed from the coast into increasingly sandy delta‐front deposits, compared to offshore equivalents. The deposits comprise extensive compound dune fields of amalgamated and increasingly clean sandbodies up‐section. Rapid deposition of significant amounts of sand led to differential subsidence and growth‐faulting in the delta front, with downthrown fault blocks further amplifying the tidal energy through funnelling. A mixed‐energy environment created along‐strike variability along the delta front with sedimentation governing process‐regime. Areas of lower sedimentation were reworked by wave and storm‐action, whereas high sedimentation rates preserved fluvially dominated mouth bars. A major transgression, however, favoured tidally dominated deposits also in these areas, attributed to increasing rugosity of the coastline. Formation of an extensive subaqueous platform between the coast and delta front dampened incoming wave energy, and tidally dominated deposits dominate the near‐shore successions. Meanwhile formation of wave‐built sand‐bars atop the platform attest to continued wave influence. The strong tidal regime led to the development of a heterolithic near‐shore tidally dominated channel system, and sandier fluvial channels up‐river. The highly meandering tidal channels incising the subaqueous platform form kilometre wide successions of inclined heterolithic stratification. The fluvially dominated channels which govern deposition on the delta plain are narrower and slightly less deep, straighter, generally symmetric and filled with cleaner sands. This study provides important insight into tidal amplification and sand redistribution during shallowing on a wide shelf, along with along‐strike process‐regime variability resulting from variations in sediment influx.

• Jelby, Mads Engholm; Śliwińska, Kasia K.; Koevoets, Maayke Jacqueline; Alsen, Peter; Vickers, Madeleine Larissa & Olaussen, Snorre [Vis alle 7 forfattere av denne artikkelen] (2020). Arctic reappraisal of global carbon-cycle dynamics across the Jurassic–Cretaceous boundary and Valanginian Weissert Event. Palaeogeography, Palaeoclimatology, Palaeoecology. ISSN 0031-0182. 555:109847, s. 1–18. doi: 10.1016/j.palaeo.2020.109847. Fulltekst i vitenarkiv
• Serck, Christopher Sæbø; Braathen, Alvar; Olaussen, Snorre; Osmundsen, Per Terje; Midtkandal, Ivar & Yperen, Anna Elisabeth van [Vis alle 7 forfattere av denne artikkelen] (2020). Supradetachment to rift basin transition recorded in continental to marine deposition; Paleogene Bandar Jissah Basin, NE Oman. Basin Research. ISSN 0950-091X. doi: 10.1111/bre.12484. Fulltekst i vitenarkiv Vis sammendrag

  A transition from supradetachment to rift basin signature is recorded in the ~1,500 m thick succession of continental to shallow marine conglomerates, mixed carbonate‐siliciclastic shallow marine sediments and carbonate ramp deposits preserved in the Bandar Jissah Basin, located southeast of Muscat in the Sultanate of Oman. During deposition, isostatically‐driven uplift rotated the underlying Banurama Detachment and basin fill ~45° before both were cut by the steep Wadi Kabir Fault as the basin progressed to a rift‐style bathymetry that controlled sedimentary facies belts and growth packages. The upper Paleocene to lower Eocene Jafnayn Formation was deposited in a supradetachment basin controlled by the Banurama Detachment. Alluvial fan conglomerates sourced from the Semail Ophiolite and the Saih Hatat window overlie the ophiolitic substrate and display sedimentary transport directions parallel to tectonic transport in the Banurama Detachment. The continental strata grade into braidplain, mouth bar, shoreface and carbonate ramp deposits. Subsequent detachment‐related folding of the basin during deposition of the Eocene Rusayl and lower Seeb formations marks the early transition towards a rift‐style basin setting. The folding, which caused drainage diversion and is affiliated with sedimentary growth packages, coincided with uplift‐isostasy as the Banurama Detachment was abandoned and the steeper Marina, Yiti Beach and Wadi Kabir faults were activated. The upper Seeb Formation records the late transition to rift‐style basin phase, with fault‐controlled sedimentary growth packages and facies distributions. A predominance of carbonates over siliciclastic sediments resulted from increasing near‐fault accommodation, complemented by reduced sedimentary input from upland catchments. Hence, facies distributions in the Bandar Jissah Basin reflect the progression from detachment to rift‐style tectonics, adding to the understanding of post‐orogenic extensional basin systems.

• Śliwińska, Kasia; Jelby, Mads; Grundvåg, Sten-Andreas; Nøhr-Hansen, H.; Alsen, P & Olaussen, Snorre (2020). Dinocyst stratigraphy of the Valanginian-Aptian Rurikfjellet and Helvetiafjellet formations on Spitsbergen, Arctic Norway. Geological Magazine. ISSN 0016-7568. 157(Special Issue 10), s. 1693–1714. doi: 10.1017/S0016756819001249. Fulltekst i vitenarkiv
• Restrepo, Dora Luz Marin; Helleren, Solveig; Varela, Alejandro Escalona; Olaussen, Snorre; Motta, Andres Felipe Cedeno & Nøhr-Hansen, Henrik [Vis alle 7 forfattere av denne artikkelen] (2020). The Middle Jurassic to lowermost Cretaceous in the SW Barents Sea: Interplay between tectonics, coarse-grained sediment supply and organic matter preservation. Basin Research. ISSN 0950-091X. 33(2). doi: 10.1111/bre.12504. Fulltekst i vitenarkiv Vis sammendrag

  Syn‐rift successions contain both prolific organic‐rich and coarse‐grained rocks, but these rocks are usually studied independently. Thus, the interplay among organic matter deposition, tectonics and sediment supply is not commonly assessed. In this study, we use well logs, Total Organic Carbon (TOC) content, biostratigraphy and seismic data from the SW Barents Sea to unravel the variability of organic‐rich successions and its interaction with potential reservoir rocks in areas affected by active normal faulting versus tectonically stable areas. Four Transgressive‐Regressive (T‐R) sequences were defined for the Middle to Upper Jurassic Fuglen Formation and for the organic‐rich Upper Jurassic to lowermost Cretaceous Hekkingen Formation. Three TOC trends, controlled by palaeobathymetric variations, and organic matter dilution, were identified within the two main organic‐rich sequences (sequences 2 and 3): (a) wells with the highest TOC values (>10 wt %) at the base of the succession; (b) wells with the highest TOC values at the top of the succession and (c) wells with high TOC values at the base and top of the succession. Our interpretation indicates that fault activity controlled the TOC trends in two different ways: Firstly, by creating a sharp topographic contrast‐triggering hyperpycnal flows, and shallowing the footwalls, where higher oxygen content and less developed stratified waters lowered organic matter preservation. Secondly, by significantly increasing the input of clastic material, which inherently led to dilution of organic matter and resulted in lower TOC values (<6 wt %). We interpret that sand deposition was controlled by the size and geomorphology of the sediment source areas. The western part of the study area (i.e. the Loppa High) was characterized by uplifted footwall islands and localized sands along their flanks, whereas the southern part (i.e. the Finnmark Platform) constituted a larger sediment source area for the Volgian age. This work has implications for a better understanding of the distribution of reservoir and source rocks in active rift basins.

• Haile, Beyene Girma; Line, Lina Hedvig; Klausen, Tore Grane; Olaussen, Snorre; Eide, Christian Haug & Jahren, Jens [Vis alle 7 forfattere av denne artikkelen] (2020). Quartz overgrowth textures and fluid inclusion thermometry evidence for basin-scale sedimentary recycling: An example from the Mesozoic Barents Sea Basin. Basin Research. ISSN 0950-091X. 33(3). doi: 10.1111/bre.12531. Fulltekst i vitenarkiv Vis sammendrag

  Sedimentary recycling has the potential to obscure source-to-sink relationships, provenance interpretations, burial history reconstructions and robust reservoir quality predictions in siliciclastic sedimentary basins. Here, we integrate petrographic and cathodoluminescence microtextures with fluid inclusion thermometry in quartz overgrowths to identify sedimentary recycling and to constrain the potential provenance candidate for recycled grains in Lower Mesozoic sandstone of the western Barents Sea basin. Four diagenetic imprints were recognized as proof of sediment recycling: (a) microtextural surface properties of overgrowths, (b) the presence of overgrowths at sutured grain contacts, (c) reversed diagenetic sequences and (d) fluid inclusions within quartz overgrowths. The diagenetic imprints confirm delivery of recycled sediments across the western Barents Sea basin. Their widespread distribution across the basin suggest that the recycled grains were derived from a drainage basin with regional-scale sediment dispersal potential during the latest Triassic. Furthermore, the drainage basin must have contained sedimentary rocks. Prior to surface exposure, the precursor sedimentary basin was subjected to burial temperatures exceeding 130°C, whereby syntaxial quartz overgrowths precipitated. This temperature indicates an uplift of around 3–4 km, which represents a significant tectonic event. Recycled quartz grains can provide insights on their provenance as they retain direct temperature records. The geothermal signatures and geographically widespread distribution of recycled quartz exclude spatially restricted intrabasinal highs and higher-temperature crystalline rocks as provenance candidates for the recycled grain portion. Our data support the contemporaneous Novaya Zemlya Fold and Thrust Belt as the most likely provenance candidate in the region. The integrated approach demonstrated herein can be used to constrain sediment recycling and partly eroded provenance candidates in sedimentary basins of equivalent setting worldwide, particularly in quartz-rich strata susceptible to sediment supply from older uplifted sedimentary basins.

• Nicolaisen, Jakob; Elvebakk, Geir; Ahokas, Juha Matti; Koefoed, J.A. Bojesen-; Olaussen, Snorre & Rinna, J. [Vis alle 8 forfattere av denne artikkelen] (2019). Characterization of upper palaeozoic organic-rich units in Svalbard: implications for the petroleum systems of the Norwegian Barents shelf. Journal of Petroleum Geology. ISSN 0141-6421. 42(1), s. 59–78. doi: 10.1111/jpg.12724. Fulltekst i vitenarkiv
• Ohm, Sverre Ekrene; Larsen, Leif; Olaussen, Snorre; Senger, Kim; Birchall, Thomas & Demchuk, Thomas [Vis alle 11 forfattere av denne artikkelen] (2019). Discovery of shale gas in organic-rich Jurassic successions, Adventdalen, Central Spitsbergen, Norway. Norwegian Journal of Geology. ISSN 2387-5844. 99(2), s. 349–376. doi: 10.17850/njg007. Fulltekst i vitenarkiv Vis sammendrag

  Thermogenic dry gas flowed from Jurassic sections in the DH5R research well drilled onshore in Adventdalen, central Spitsbergen, Arctic Norway. The DH5R gas originates from the organic-rich units of the mudstone-dominated Middle Jurassic to Lower Cretaceous Agardhfjellet Formation, which is the onshore equivalent to the Fuglen Formation and the prolific oil and gas generating Hekkingen Formation in the southern Barents Shelf. Low-permeable, low-porosity sandstones from the Upper Triassic De Geerdalen Formation of the neighbouring DH4 well were oil-stained and gas was also collected from this interval. Gas from the two stratigraphic intervals have different compositions; the gas from the Agardhfjellet Formation is drier and isotopically heavier than the gas from the Upper Triassic succession. Both gases originated from source rocks of maturity near the end of the oil window (1.1 < Ro < 1.4% Ro). Maceral analyses of the Agardhfjellet Formation indicate that the more silty parts contain a high percentage of vitrinite-rich type III kerogen, whereas the clay-dominated parts are rich in liptinitic type II kerogen. The Agardhfjellet Formation has therefore the potential to generate both oil and gas. Several simulations based on pressure data and flow rates from the DH5R well were run to evaluate if the gas accumulation in the Agardhfjellet Formation is producible, i.e., can it be commercial shale gas. The models demonstrate how changes in the drainage area size and form, well types (vertical versus horizontal), number and length of induced fractures and thickness of the Agardhfjellet Formation affect gas production rates and producible volumes. Despite uncertainties in the input data, simulations indicate that the shale gas accumulation characterised in Adventdalen is producible. This gas can have major environmental benefits as an alternative for local power generation compared to coal.

• Olaussen, Snorre; Senger, Kim; Braathen, Alvar; Grundvåg, Sten-Andreas & Mørk, Atle (2019). You learn as long as you drill; research synthesis from the Longyearbyen CO2 Laboratory, Svalbard, Norway. Norwegian Journal of Geology. ISSN 2387-5844. 99(2), s. 157–188. doi: 10.17850/njg008. Fulltekst i vitenarkiv Vis sammendrag

  From 2007 to 2015, eight wells were drilled and fully cored to test the feasibility of storing CO2 emitted from the coal-fueled power plant in Longyearbyen, Svalbard. The drilling campaign identified three water-bearing sandstone aquifers; i) a lower aquifer in Upper Triassic strata; ii) a middle aquifer in Upper Triassic to Middle Jurassic; and iii) an upper aquifer in Lower Cretaceous strata. Only the two former are regarded as potential CO2 storage units. Both units are unconventional reservoirs (storage units) consisting of fractured, low-porosity and low-permeability sandstones. The storage units are capped by a c. 400 m-thick Middle Jurassic to Lower Cretaceous mudstone-dominated succession, which acts as an efficient top seal. In addition, a c. 120 m-thick zone of permafrost provides an additional seal. Apart from characterising the CO2 storage and cap-rock system, the drilling resulted in several unexpected results. These include: (a) the detection of severe underpressure of approximately 50 bar in the two storage units, (b) the discovery of gravity-flow deposits attributed to a hitherto unknown Hauterivian clastic wedge, and (c) the detection of producible thermogenic shale gas at a depth of 640 to 700 m. Moreover, core and wireline data from the wells combined with correlation to equivalent strata in nearby outcrops provide new insights into the age and depositional evolution of the succession. Thus, the data obtained from this project contributes to the regional stratigraphic understanding of the Mesozoic succession in Svalbard and the northern Barents Shelf. Until now, nearly 70 papers have been published in international peer-reviewed journals using data from or part of the Longyearbyen CO2 Laboratory. In addition, 13 PhD candidates and 27 master students, linked to the project or using obtained data from the project, have graduated. The main achievement of our studies is that we have shown that unconventional fractured reservoirs are suitable for storing CO2.

• Liira, Martin; Noormets, Riko; Seep, Holar; Kekisev, Ott; Maddison, Martin & Olaussen, Snorre (2019). Sediment geochemical study of hydrocarbon seeps in Isfjorden and Mohnbukta: a comparison between western and eastern Spitsbergen, Svalbard. Arktos. ISSN 2364-9453. 5, s. 49–62. doi: 10.1007/s41063-019-00067-7. Fulltekst i vitenarkiv
• Hammer, Øyvind; Alsen, Peter; Grundvåg, Sten-Andreas; Jelby, Mads E.; Nøhr-Hansen, Henrik & Olaussen, Snorre [Vis alle 9 forfattere av denne artikkelen] (2019). Comment on ‘Redox conditions, productivity, and volcanic inputduring deposition of uppermost Jurassic and Lower Cretaceousorganic-rich siltstones in Spitsbergen, Norway’ by Rakocinski et al.(2018). Cretaceous research (Print). ISSN 0195-6671. 96, s. 241–243. doi: 10.1016/j.cretres.2018.09.017. Fulltekst i vitenarkiv
• Abay, Tesfamariam Berhane; Karlsen, Dag Arild; Olaussen, Snorre & Pedersen, Jon Halvard (2019). Organic geochemistry of petroleum in the Cambro-Ordovician succession of NY Friesland, Spitsbergen, Svalbard. 29th International Meeting on Organic Geochemistry. doi: 10.3997/2214-4609.201902714. Fulltekst i vitenarkiv
• Jelby, Mads Engholm; Grundvåg, Sten-Andreas; Helland-Hansen, William; Olaussen, Snorre & Stemmerik, Lars (2019). Tempestite facies variability and storm‐depositional processes across a wide ramp: Towards a polygenetic model for hummocky cross‐stratification. Sedimentology. ISSN 0037-0746. 67, s. 742–781. doi: 10.1111/sed.12671. Fulltekst i vitenarkiv Vis sammendrag

  The hydrodynamic mechanisms responsible for the genesis and facies variability of shallow‐marine sandstone storm deposits (tempestites) have been intensely debated, with particular focus on hummocky cross‐stratification. Despite being ubiquitously utilized as diagnostic elements of high‐energy storm events, the full formative process spectrum of tempestites and hummocky cross‐stratification is still to be determined. In this study, detailed sedimentological investigations of more than 950 discrete tempestites within the Lower Cretaceous Rurikfjellet Formation on Spitsbergen, Svalbard, shed new light on the formation and environmental significance of hummocky cross‐stratification, and provide a reference for evaluation of tempestite facies models. Three generic types of tempestites are recognized, representing deposition from: (i) relatively steady and (ii) highly unsteady storm‐wave‐generated oscillatory flows or oscillatory‐dominated combined‐flows; and (iii) various storm‐wave‐modified hyperpycnal flows (including waxing–waning flows) generated directly from plunging rivers. A low‐gradient ramp physiography enhanced both distally progressive deceleration of the hyperpycnal flows and the spatial extent and relative magnitude of wave‐added turbulence. Sandstone beds display a wide range of simple and complex configurations of hummocky cross‐stratification. Features include ripple cross‐lamination and ‘compound’ stratification, soft‐sediment deformation structures, local shifts to quasi‐planar lamination, double draping, metre‐scale channelized bed architectures, gravel‐rich intervals, ‘inverse to normal’ grading, and vertical alternation of sedimentary structures. A polygenetic model is presented to account for the various configurations of hummocky cross‐stratification that may commonly be produced during storms by wave oscillations, hyperpycnal flows and downwelling flows. Inherent storm‐wave unsteadiness probably facilitates the generation of a wide range of hummocky cross‐stratification configurations due to: (i) changes in near‐bed oscillatory shear stresses related to passing wave groups or tidal water‐level variations; (ii) multidirectional combined‐flows related to polymodal and time‐varying orientations of wave oscillations; and (iii) syndepositional liquefaction related to cyclic wave stress. Previous proximal–distal tempestite facies models may only be applicable to relatively high‐gradient shelves, and new models are necessary for low‐gradient settings.

• Müller, Reidar; Klausen, Tore Grane; Faleide, Jan Inge; Olaussen, Snorre; Eide, Christian Haug & Suslova, Anna A. (2019). Linking regional unconformities in the Barents Sea to compression-induced forebulge uplift at the Triassic-Jurassic transition. Tectonophysics. ISSN 0040-1951. 765, s. 35–51. doi: 10.1016/j.tecto.2019.04.006. Fulltekst i vitenarkiv Vis sammendrag

  The Triassic-Jurassic transition marks an important change in the basin configuration of the Greater Barents Sea. A contiguous basin with km-thick sedimentary successions changed into a partitioned basin with uplift in the west and foreland basins in the east with significant implication for the basin infill history. Our study employs a range of different high-resolution datasets from a distal part of the basin which unravels the complex pattern of differential uplift and erosion in the basin during this period. We record for the first time distinct angular unconformities between Upper Triassic strata and overlying Lower Jurassic strata within the basin, showing that large parts of it formed topographic highs. Our study links these angular unconformities to compression induced by the Novaya Zemlya Fold and Thrust Belt. A heterolithic basement below a thick sedimentary succession where the fold belt developed created a complex uplift pattern in the basin, at the same time similar to but different from typical forebulge areas. Compression caused inversion of older basement rooted faults defining platforms and graben systems throughout western parts of the Barents Sea basin, in addition to salt remobilization that resulted in differential uplift and erosion. These local zones of uplift controlled the sediment distribution pattern to the basin at a time when the most important reservoir units in the basin were deposited. This new understanding of the basin development explains hitherto enigmatic sequence boundaries that has inspired complex paleogeographic models in the past.

• Senger, Kim; Brugmans, Peter; Grundvåg, Sten-Andreas; Jochmann, Malte Michel; Nøttvedt, Arvid & Olaussen, Snorre [Vis alle 8 forfattere av denne artikkelen] (2019). Petroleum, coal and research drilling onshore Svalbard: a historical perspective. Norwegian Journal of Geology. ISSN 2387-5844. 99(3). doi: 10.17850/njg99-3-1. Fulltekst i vitenarkiv Vis sammendrag

  The beginning of the Norwegian oil industry is often attributed to the first exploration drilling in the North Sea in 1966, the first discovery in 1967 and the discovery of the supergiant Ekofisk field in 1969. However, petroleum exploration already started onshore Svalbard in 1960 with three mapping groups from Caltex and exploration efforts by the Dutch company Bataaffse (Shell) and the Norwegian private company Norsk Polar Navigasjon AS (NPN). NPN was the first company to spud a well at Kvadehuken near Ny-Ålesund in 1961. This drilling marked the start of an exciting period of petroleum exploration in Svalbard, with eighteen exploration wells drilled in the period from 1961 to 1994. The deepest well so far, Caltex’s Ishøgda-I near Van Mijenfjorden, reached 3304 m in 1966. NPN was involved in nine of the eighteen wells. The remaining wells were drilled by American (Caltex/Amoseas), Belgian (Fina), French (Total), Soviet/Russian (Trust Arktikugol), Swedish (Polargas Prospektering) and Norwegian companies Norsk Hydro and Store Norske Spitsbergen Kulkompani. None of the wells resulted in commercial discoveries, though several wells encountered gas in measureable quantities. Only the two wells drilled in the early 1990s were drilled on structures defined using a sparse 2D seismic grid, while the other wells were drilled based on geological mapping at the surface. Furthermore, more recent research and coal exploration boreholes have confirmed moveable hydrocarbons in close proximity to the Longyearbyen and Pyramiden settlements. In this contribution, we present a historical and brief geological overview of the petroleum exploration wells onshore Svalbard. We illustrate that the eighteen petroleum exploration wells have together penetrated over 29 km of stratigraphy, with the Late Palaeozoic–Mesozoic successions particularly well covered. Coal exploration and research boreholes primarily focus on the Mesozoic–Cenozoic successions. As such, the boreholes represent an important window to decipher the stratigraphic evolution of both Svalbard and the greater Barents Shelf.

• Klausen, Tore Grane; Müller, Reidar; More, Miquel Poyatos; Olaussen, Snorre & Stueland, Eirik (2019). Tectonic, provenance and sedimentological controls on reservoir characteristics in the Upper Triassic–Middle Jurassic Realgrunnen Subgroup, SW Barents Sea. Geological Society Special Publication. ISSN 0305-8719. 495, s. 237–261. doi: 10.1144/SP495-2018-165. Fulltekst i vitenarkiv
• Lord, Gareth Steven; Mørk, Mai Britt Engeness; Mørk, Atle & Olaussen, Snorre (2019). Sedimentology and petrography of the Svenskøya Formation on Hopen, Svalbard: an analogue to sandstone reservoirs in the Realgrunnen Subgroup. Polar Research. ISSN 0800-0395. 38. doi: 10.33265/polar.v38.3523. Fulltekst i vitenarkiv Vis sammendrag

  On the island of Hopen, in the Svalbard Archipelago, the Svenskøya Formation is a succession 35 m in thickness, consisting primarily of sandstone beds and forming the youngest strata exposed on the island. We present a sedimentological and petrographic study of the formation and compare the unit with its exposures on Wilhelmøya and in Kong Karls Land, Svalbard. We also compare the onshore characteristics of the Svenskøya Formation with those of the Tubåen Formation, its time-equivalent unit in the Sentralbanken area of the northern Barents Sea. On Hopen, the Svenskøya Formation is interpreted as representing coarse clastic sediments deposited in a fluvial to tidal setting, prior to being overlain by a thin interval composed of tidal channel and marine shale deposits. The unit sits atop the regional “Rhaetian Unconformity” and represents sediments deposited during a regressive system that terminates at a flooding surface representing a local transgression of the palaeo-coastline. Petrographic studies show the formation as being arkosic, both on Hopen and in the Sentralbanken area. The reservoir quality of sandstone samples recovered from Hopen is somewhat lower compared to sandstone reservoirs in the Sentralbanken area. We attribute this to greater effects of diagenesis in the Hopen area, which caused increased compaction, mineral dissolution and extensive precipitation of pore-filling clay minerals.

• Nakrem, Hans Arne; Sorento, Tone; Olaussen, Snorre & Stemmerik, Lars (2019). Depositional environment control on bryozoan faunas, Early Permian (Artinskian) Gipshuken Formation, Spitsbergen, Arctic Norway. Australasian Palaeontological Memoirs. ISSN 2205-8877. 52, s. 101–107. doi: 10.1111/sed.12640. Fulltekst i vitenarkiv
• Grundvåg, Sten-Andreas; Jelby, Mads Engholm; Śliwińska, Kasia Kamila; Nøhr-Hansen, Henrik; Aadland, Tore & Sandvik, Sara Elvelund [Vis alle 9 forfattere av denne artikkelen] (2019). Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data. Norwegian Journal of Geology. ISSN 2387-5844. 99(2), s. 253–284. doi: 10.17850/njg006. Fulltekst i vitenarkiv Vis sammendrag

  The Lower Cretaceous succession in Svalbard is commonly considered as an important analogue to age-equivalent strata on the Barents Shelf which are sporadically targeted by exploration wells. In this study, the stratigraphic and genetic relationship between the Rurikfjellet (open marine), Helvetiafjellet (paralic) and Carolinefjellet (open marine) formations of the Lower Cretaceous succession in Svalbard is evaluated by combining sedimentological outcrop studies with well log and core data across Nordenskiöld Land, central Spitsbergen. Sedimentological characteristics and stratigraphic units are mapped within a refined dinocyst biostratigraphic framework, enabling relatively well-constrained palaeogeographic reconstructions. The Valanginian–lowermost Barremian Rurikfjellet Formation consists of a lower shale-dominated unit of offshore origin which grades upwards into storm-reworked lower shoreface sandstones displaying hummocky cross-stratification. Local occurrences of prodeltaic successions and thick successions of gravity flow deposits containing coal-bearing slump blocks of delta plain origin in some wells, reveal a late Hauterivian progradational pulse which has previously not been recorded in Svalbard. The lower Barremian– lower Aptian Helvetiafjellet Formation consists of fluvial braidplain and paralic deposits which rest unconformably on the Rurikfjellet Formation across the entire study area, reflecting regional uplift and widespread subaerial exposure prior to the onset of paralic deposition. The Helvetiafjellet Formation exhibits increased marine influence upwards, and in the investigated cores the uppermost part of the unit consists of wave-reworked mouth-bar deposits which are truncated by a transgressive conglomerate lag dominated by extrabasinal lithic clasts and intraformational siderite clasts. An up to 10 m-thick, regionally extensive, organic-rich (TOC up to 2.1 wt.%) shale unit of early Aptian age marks the base of the overlying Carolinefjellet Formation. The shale accumulated during a regional flooding event which drowned and eventually transformed the Helvetiafjellet Formation coastal plain into a shallow shelf. The organic facies of the shale unit (Type II–III kerogen) and a high Pr/Ph ratio (>2), in combination with abundant long-chained n-alkanes, suggest that the unit was deposited in a suboxic paralic marine environment strongly influenced by input of terrestrial organic matter. The investigated succession exhibits stratigraphic and petrographic resemblance to age-equivalent strata in NE Greenland, suggesting that these successions may have formed part of the same drainage system located on the northwestern margin of the Barents Shelf. Thus, by highlighting the Early Cretaceous palaeogeographic evolution in Svalbard, this study contributes to the regional stratigraphic understanding of the Lower Cretaceous succession on the wider northern Barents Shelf.

• Rossi, Valentina Marzia; Olaussen, Snorre; Staine, Ivan Nicola & Gennaro, Matteo (2019). Development of the Middle Triassic Kobbe Formation shelf-margin prism and transgressive-regressive cycles on the shelf (Hammerfest Basin, SW Barents Sea). Marine and Petroleum Geology. ISSN 0264-8172. 111, s. 868–885. doi: 10.1016/j.marpetgeo.2019.08.043. Fulltekst i vitenarkiv
• Sorento, Tone; Olaussen, Snorre & Stemmerik, Lars (2019). Controls on deposition of shallow marine carbonates and evaporites – lower Permian Gipshuken Formation, central Spitsbergen, Arctic Norway. Sedimentology. ISSN 0037-0746. 67(1), s. 207–238. doi: 10.1111/sed.12640. Fulltekst i vitenarkiv
• Smyrak-Sikora, Aleksandra; Johannessen, Erik P.; Olaussen, Snorre; Sandal, Geir Løken & Braathen, Alvar (2018). Sedimentary architecture during Carboniferous rift initiation – the arid Billefjorden Trough, Svalbard. Journal of the Geological Society. ISSN 0016-7649. 176(2), s. 225–252. doi: 10.1144/jgs2018-100. Fulltekst i vitenarkiv
• Rismyhr, Bjarte; Bjærke, Tor; Olaussen, Snorre; Mulrooney, Mark Joseph & Senger, Kim (2018). Facies, palynostratigraphy and sequence stratigraphy of the Wilhelmøya Subgroup (Upper Triassic–Middle Jurassic) in western central Spitsbergen, Svalbard. Norwegian Journal of Geology. ISSN 2387-5844. 99(4), s. 35–64. doi: 10.17850/njg001. Fulltekst i vitenarkiv Vis sammendrag

  The Wilhelmøya Subgroup (Norian–Bathonian) is considered as the prime storage unit for locally produced CO2 in Longyearbyen on the Arctic archipelago of Svalbard. We here present new drillcore and outcrop data and refined sedimentological and sequence-stratigraphic interpretations from western central Spitsbergen in and around the main potential CO2-storage area. The Wilhelmøya Subgroup encompasses a relatively thin (15–24 m) siliciclastic succession of mudstones, sandstones and conglomerates and represents an unconventional potential reservoir unit due to its relatively poor reservoir properties, i.e., low-moderate porosity and low permeability. Thirteen sedimentary facies were identified in the succession and subsequently grouped into five facies associations, reflecting deposition in various marginal marine to partly sediment-starved, shallow shelf environments. Palynological analysis was performed to determine the age and aid in the correlation between outcrop and subsurface sections. The palynological data allow identification of three unconformity-bounded sequences (sequence 1–3). These sequences record intermittent deposition in the Early Norian, Early–Middle Toarcian, and Late Toarcian–Aalenian, interrupted by extended periods of erosion, bypass and/or non-deposition. The stratigraphically condensed development of the Wilhelmøya Subgroup in western central Spitsbergen is interpreted to be the result of very low subsidence rates coupled with a physiographic setting characterised by a very gentle depositional gradient. This facilitated rapid shoreline shifts in response to even relatively modest variations in relative sea level with considerable influence on the resulting depositional patterns. We present a revised depositional model for the regionally distinct Brentskardhaugen Bed at the top of the Wilhelmøya Subgroup involving condensation and partial reworking of a series of Upper Toarcian–Aalenian, high-frequency sequences. Coarse-grained extraformational fractions observed within conglomerates of the Wilhelmøya Subgroup are suggested to have been supplied from uplifted and exposed margins to the west (northern Greenland) and north (northern Svalbard).

• Mulrooney, Mark Joseph; Larsen, Leif; Stappen, Jeroen Van; Rismyhr, Bjarte; Senger, Kim & Braathen, Alvar [Vis alle 10 forfattere av denne artikkelen] (2018). Fluid flow properties of the Wilhelmøya Subgroup, a potential unconventional CO2 storage unit in central Spitsbergen. Norwegian Journal of Geology. ISSN 2387-5844. 99(4), s. 85–116. doi: 10.17850/njg002. Fulltekst i vitenarkiv Vis sammendrag

  The Upper Triassic to Middle Jurassic Wilhelmøya Subgroup forms one of the more suitable reservoir units on the Norwegian Arctic archipelago of Svalbard. The target siliciclastic storage unit, which is encountered at approx. 670 m depth at the potential injection site in Adventdalen, central Spitsbergen, is a severely under-pressured (at least 35 bar), tight and compartmentalised reservoir with significant contribution of natural fractures to permeability. In this contribution, we characterise the 15–24 m-thick Wilhelmøya Subgroup storage unit using both borehole and outcrop data and present water-injection test results that indicate the presence of fluid-flow barriers and the generation of new, and propagation of pre-existing natural fractures during injection. Whole core samples from drillcores and outcrops were sampled for pore network characterisation and analysed using high-resolution X-ray computed tomography (Micro-CT). We demonstrate that heterogeneities such as structural discontinuities, igneous bodies and lateral facies variations, as examined in well core and equivalent outcrops, will strongly influence fluid flow in the target reservoir, both by steering and baffling fluid migration. Many of these heterogeneities are considered to be subseismic, and their detailed characterisation is important to predict subsurface CO2 storage potential and optimise injection strategy.

• Abay, Tesfamariam Berhane; Karlsen, Dag Arild; Pedersen, Jon Halvard; Olaussen, Snorre & Backer-Owe, Kristian (2018). Thermal maturity, hydrocarbon potential and kerogen type of some Triassic-Lower Cretaceous sediments from the SW Barents Sea and Svalbard. Petroleum Geoscience. ISSN 1354-0793. 24(3), s. 349–373. doi: 10.1144/petgeo2017-035. Fulltekst i vitenarkiv
• Koevoets, Maayke Jacqueline; Hammer, Øyvind; Olaussen, Snorre; Senger, Kim & Smelror, Morten (2018). Integrating subsurface and outcrop data of the Middle Jurassic to Lower Cretaceous Agardhfjellet Formation in central Spitsbergen. Norwegian Journal of Geology. ISSN 2387-5844. 98(4). doi: 10.17850/njg98-4-01. Fulltekst i vitenarkiv Vis sammendrag

  The Longyearbyen CO2 storage project drilling and coring campaign in central Spitsbergen provided new insights on the shale-dominated Middle Jurassic to Lower Cretaceous Agardhfjellet Formation, which is the onshore counterpart to the Fuglen Formation and the prolific source rocks of the Hekkingen Formation in the Barents Sea. Logs of magnetic susceptibility, organic carbon content, organic carbon isotopes and XRF geochemistry on the cores, together with wireline logs, biostratigraphy and sedimentology, have made it possible to refine the interpretation of the depositional environment and to identify transgressive-regressive (TR) sequences. Several key sequence-stratigraphic surfaces are identified and suggested to be correlative in Central Svalbard, and four of them, although not necessarily chronostratigraphic, also to surfaces in the Barents Sea. Due to the nearly flat-lying thrust faults in the upper décollement zone of the West Spitsbergen Fold and Thrust Belt, there is some concern about the lateral correlation of the sequences within Spitsbergen. However, some of the TR sequence surfaces appear to be of regional importance and are recognised both onshore Svalbard and offshore on the Barents Shelf. The observations suggest a shallow-marine shelf depositional environment within an epicontinental sea with variable dysoxic, anoxic and oxic sea-floor conditions. The majority of the facies vary from outer shelf to transition zone or prodelta and lower shoreface/distal delta front. In one outcrop, proximal facies, i.e., delta front or middle shoreface, are recognised. In our study area the nearly 250 m-thick, fine-grained Agardhfjellet Formation is proposed to represent distal shoreline clinoforms and a precursor to the overlying forward- and southward-stepping wedge of the Valanginian Rurikfjellet Formation and the Barremian to Early Aptian Helvetiafjellet Formation.

• Stappen, Jeroen Van; Meftah, Reduane; Boone, Marijn A.; Bultreys, Tom; Kock, Tim De & Blykers, Benjamin [Vis alle 9 forfattere av denne artikkelen] (2018). In situ triaxial testing to determine fracture permeability and aperture distribution for CO2 sequestration in Svalbard, Norway. Environmental Science and Technology. ISSN 0013-936X. 52(8), s. 4546–4554. doi: 10.1021/acs.est.8b00861. Fulltekst i vitenarkiv
• Smelror, Morten; Larssen, Geir Birger; Olaussen, Snorre; Rømuld, Arnfinn & Williams, Robert W (2018). Late Triassic to Early Cretaceous palynostratigraphy of Kong Karls Land, Svalbard, Arctic Norway, with correlations to Franz Josef Land, Arctic Russia. Norwegian Journal of Geology. ISSN 2387-5844. 98(4). doi: 10.17850/njg004. Fulltekst i vitenarkiv
• Olaussen, Snorre; Larssen, Geir Birger; Helland-Hansen, William; Johannessen, Erik P.; Nøttvedt, Arvid & Riis, Fridtjof [Vis alle 9 forfattere av denne artikkelen] (2018). Mesozoic strata of Kong Karls Land, Svalbard, Norway; a link to the northern Barents Sea basins and platforms. Norwegian Journal of Geology. ISSN 2387-5844. 98(4), s. 1–69. doi: 10.17850/njg98-4-06. Fulltekst i vitenarkiv
• Restrepo, Dora Luz Marin; Varela, Alejandro Escalona; Grundvåg, Sten-Andreas; Olaussen, Snorre; Sandvik, Sara & Sliwinska, Kasia (2018). Unravelling key controls on the rift climax to post-rift fill of marine rift basins: insights from 3D seismic analysis of the Lower Cretaceous of the Hammerfest Basin, SW Barents Sea. Basin Research. ISSN 0950-091X. 30(4), s. 587–612. doi: 10.1111/bre.12266. Fulltekst i vitenarkiv Vis sammendrag

  In this study, we investigate key factors controlling the rift climax to post‐rift marine basin fill. We use two‐ and three‐dimensional seismic data in combination with sedimentological core descriptions from the Hammerfest Basin, south‐western Barents Sea to characterize and analyse the tectonostratigraphy and seismic facies of the Lower Cretaceous succession. Based on our biostratigraphic analyses, the investigated seismic facies are correlated to 5–10 million year duration sequences that make up the stratigraphic framework of the basin fill. The seismic facies suggest the basin fill was deposited in shallow to deep‐marine conditions. During rift climax in Volgian/Berriasian to Barremian times, a fully linked fault array controlled the formation of slope systems consisting of gravity flow deposits along the southern margin of the basin. Renewed uplift of the Loppa High north of the basin provided coarse‐grained sediments for fan deltas and shorelines that developed along the northern basin margin. During the early to middle late Aptian, the input of coarse‐grained sediments occurred mainly in the NW and SW corners of the basin, reflecting renewed uplift‐induced topography in the western flank of the Loppa High and along the western Finnmark Platform. The lower Albian part of the basin fill is interpreted as a post‐rift succession, where the remnant topography associated with the Finnmark Platform continued to provide sediments to prograding fan deltas and adjacent shorelines. During the Albian, a series of faults were reactivated in the northern part of the basin, and footwall wedges comprising various gravity flow deposits occur along these faults. During the latest Albian to Cenomanian, the south‐eastern part of the Loppa High was flooded by a rise in eustatic sea‐level and differential subsidence. However, the western part of the high remained exposed and acted as a sediment source for a shelf‐margin system prograding towards the SE. It is concluded that the rift climax succession is controlled by: along strike variability of throw and steps of the main bounding faults; the diachronous movement of the faults; and the nature of the feeder system. The evolution of the post‐rift succession may be controlled by rifting in adjacent basins which preferentially renew sources of sediments; local reactivation of faults; and local remnant topography of the basin flanks. We suggest that existing tectonostratigraphic models for rift basins should be updated, to incorporate a more regional perspective and integrating variables such as the influence of adjacent rift systems.

• Mulrooney, Mark; Rismyhr, Bjarte; Yenwongfai, Honore Dzekamelive; Leutscher, Johan; Olaussen, Snorre & Braathen, Alvar (2018). Impacts of small-scale faults on continental to coastal plain deposition: Evidence from the Realgrunnen Subgroup in the Goliat field, southwest Barents Sea, Norway. Marine and Petroleum Geology. ISSN 0264-8172. 95, s. 276–302. doi: 10.1016/j.marpetgeo.2018.04.023. Fulltekst i vitenarkiv Vis sammendrag

  In this study we synthesise sedimentological, fault, and Amplitude Versus Angle (AVA) analysis and propose that the Fruholmen and Tubåen formations (Realgrunnen Subgroup) are syn-kinematic deposits that record a previously undocumented early phase of Mesozoic rifting on the Troms-Finnmark fault Complex and within the Hammerfest Basin. The Realgrunnen Subgroup hosts one of two Triassic reservoirs currently being produced in the Goliat field. Here, the subgroup sits unconformably on top of the Storfjorden Subgroup (Carnian Snadd Formation). Away from the Goliat field, which is characterised by a periclinal anticline, the Realgrunnen Subgroup also comprises the Lower–Middle Jurassic Nordmela and Stø formations. Sedimentological analysis of six exploration wells reveals that the Fruholmen Formation was deposited in a prodelta to delta plain environment where tide-influenced and fluvial-dominated distributary channels are represented by clay/siltstones and very fine grained sandstones. The overlying Tubåen Formation is characterised by medium to very coarse-grained deposits (locally conglomeratic) and represents a widespread braid plain with localised alluvial fans. Displacement profiles of faults and along-fault thickness variations demonstrate that an immature fault system was active during deposition of the Realgrunnen Subgroup. A series of unconnected fault segments hosted isolated sub-basins and erosional catchment areas in their hanging and footwalls, respectively. An AVA attribute map generated from a 10 ms interval of the uppermost part of the subgroup reveals gross sand-prone depositional bodies, i.e., individual and amalgamated channels, (some of which show meandering geometries), ox-bow lakes and alluvial fans. Sand bodies frequently show elongate geometries parallel to faults indicative of syn-depositional fault-related subsidence. Driving mechanisms responsible for the Norian to Rhaetian event may relate to contemporaneous rejuvenation of the Fennoscandian hinterland, development of the Novaya Zemlya fold-and-thrust belt and/or the early Cimmerian tectonic phase in northern Europe.

• Matysik, Michal; Stemmerik, Lars; Olaussen, Snorre & Brunstad, Harald (2018). Diagenesis of spiculites and carbonates in a Permian temperate ramp succession-Tempelfjorden Group,Spitsbergen, Arctic Norway. Sedimentology. ISSN 0037-0746. 65(3), s. 745–774. doi: 10.1111/sed.12404. Fulltekst i vitenarkiv
• Tågholt, Tone Sorento; Stemmerik, Lars & Olaussen, Snorre (2018). Upper Permian carbonates at the northern edge of the Zechstein basin, Utsira High, Norwegian North Sea. Marine and Petroleum Geology. ISSN 0264-8172. 89(3), s. 635–652. doi: 10.1016/j.marpetgeo.2017.10.030. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Olaussen, Snorre; Müller, Reidar; Nakrem, Hans Arne & Stemmerik, Lars (2025). Hirnantian (Upper Ordovician) and Pennsylvanian tropical low latitude deposits in the Oslo Region as examples of eustatic forcing during global icehouse events. NGF Abstracts and Proceedings of the Geological Society of Norway. 2025-01(1), s. 75–76. doi: https:/geologi.no/konferanser/vinterkonferanser/abstracts/file/298-abst-vk25. Fulltekst i vitenarkiv Vis sammendrag

  The mid Ordovician – “mid” Silurian (Wenlock) and Pennsylvanian successions in the Oslo Region were deposited in subtropical and tropical climate at middle to low latitudes during the two Palaeozoic global icehouse events. Given tectonic quiescence, basins with an abrupt shift in major facies associations, and presence of regional corelative hiatuses, lacunas, karst, subaerial unconformity surfaces and local incised valley fill can be linked to high amplitude eustacy by waxing and waning of ice caps. The Upper Ordovician to Wenlock and Pennsylvanian successions in the Oslo Region are both suggested to be deposited in basins with an allover tectonic quiescence, then deposits should be more sensitive to eustatic rather than tectonic forcing.

• Olaussen, Snorre; Dahlgren, Sven Harald; Falcon-Lang, Howard J.; Larsen, Bjørn Tore; Müller, Reidar & Nakrem, Hans Arne (2024). Pennsylvanian facies and sequence stratigraphic analysis in the Oslo Graben: distinguishing tectonic and eustatic forcing during initial rifting. Fulltekst i vitenarkiv Vis sammendrag

  The Pennsylvanian Asker Group of Norway, up to 90 m thick, comprises the basal sedimentary-fill of the Carboniferous -Permian Oslo Rift, a volcanically active basin. Three stratigraphic units are recognized, from base to top, as the Kolsås, Tanum and Skaugum formations. Minor extensional tectonism occurred during deposition of the Asker Group. However, during the Late Paleozoic icehouse, high amplitude eustasy was another factor influencing base-level, and in this presentation, we present evidence to distinguish fault-controlled depositional systems influenced by tectonism and eustatic controls. The Kolsås Formation comprises red beds deposited within alluvial plain environments developed during an interval of passive subsidence. In contrast the overlying Tanum Formation shows a transgressive-regressive pattern, commencing with terrestrial facies comprising the deposits of ephemeral streams and flood plains with thick calcretes, and passing upward into shoreface/delta front facies capped by ?Moscovian shallow marine limestone, before being partly eroded by braid plain deposits, marking renewed base-level fall. The regional fluvial paleoflow direction in the Tanum Formation is towards the master faults. Drainage pattern, growth faulting and the widespread coarsening upward trend of the Kolsås and Tanum formations all suggest an upward increasing tectonic activity in a dip slope setting within the initial rift phase. A Kasimovian-Gzhelian (?Stephanian B/C) plant-fossil rich succession of wetland, lacustrine and bay mouth bar facies is sandwiched between braid plain facies of the Tanum Formation and an overlying volcanoclastic fanglomerate of the Skaugum Formation is indicative of a sudden sea level rise. The abrupt changes in facies and numerous hiatuses or lacunas seen in the Pennsylvanian Asker Group are probably linked to Pennsylvanian glacio-eustasy, and the enigmatic late Moscovian marine incursion in the Tanum Formation might be correlative with the amplified eustatic signal close to the Moscovian-Kasimovian boundary in the US midcontinental and Donets Basin coastal onlap datasets.

• Olaussen, Snorre; Stemmerik, Lars; Dahlin, Anders; Johannessen, Erik P. & Smyrak-Sikora, Aleksandra Anna (2023). Mid Pennsylvanian key sequence stratigraphic surface in the northern Laurasia. A response of glacio‐eustasy? Fulltekst i vitenarkiv Vis sammendrag

  In the northern part of Laurasia Carboniferous to Permian continental rift basins form precursors to the break‐up of Pangea. The fill of these basins follows the classic rift development with tripartite autogenic processes characteristic of the initial‐, syn‐ and postrift phases. Pennsylvanian initial rift basin fill‐deposits consist of alluvial red beds passing upward to paralic deposits. The syn rift fill often exhibit a syn‐kinematic mixed siliciclasticcarbonate‐evaporitic succession in the Arctic whereas during the post rift phase an extensive warm water carbonates platform was established. The Pennsylvanian was a period with icehouse climate and significant glacio‐eustasy, and it is a challenge, particu-larly in the initial and syn rift phases, to distinguish sequences caused by externally forced (glacio‐eustasy) and autogenic processes. In well exposed rift basins such as the Billefjorden Trough, Spitsbergen, the wedge-shaped sedimentary rock successions i.e., growth basin geometries, drainage patterns and abrupt change in facies associations can be clearly mapped and many of these features can be related to move-ments along master faults and hanging wall dip slope faults. Some lower frequency flooding events might be caused by glacio‐eustasy and without high resolution timelines these flooding surfaces must live with yin yang i.e., whether the flooding is glacio‐eustatic or tectonic forcing. Studies of time equivalent strata on rift shoulders, terraces and particularly platforms adja-cent to the rift basins are considered as better places to recognise regional key sequence stratigraphic surfaces caused by glacio‐eustasy forcing. The late Mississippian to Early Permian successions in the coastal area of the Wahlenbergfjorden, Nordaustlandet, Svalbard are deposited on a platform. Here, a prominent Moscovian flooding event drowned a continental to paralic Missi-ssippian succession. Age equivalent flooding surfaces occur further west and can be recognised across entire Spitsbergen e.g., the Nordfjorden Block, Brøggerhalv-øya and likely also at Treskelen. Further, this flooding event is recognized on Bjørnøya, Loppa High, and in North Greenland. The enigmatic Moscovian transgress-ion in the Oslo Graben seems to be linked to the same flooding event. Late Moscovian (Desmoinesian) sea level rise is recognised in the midcontinental US at the same stratigraphic level as a major coastal onlap in the Donets Basin, Ukraine. This flooding event is now linked to retreat of glaciers in southern part of Pangea and the onset of a late Moscovian interglacial period. We suggest that the late Moscovian flooding event is a candidate for a mappable regional and near chrono-stratigraphic sequence stratigraphic surface in the northern Laurasia. Improved stratigraphic resolution by integration of biostratigraphy, isotopic excursions, absolute dating of this surface might be very important for reconstruction of basin history and paleogeographic reconstructions of the Arctic.

• Olaussen, Snorre; Ganerød, Morgan; Gradmann, Sofie; Slagstad, Trond & Stemmerik, Lars (2023). Late Mississippian rift magmatism in the High Arctic, preliminary results from Spitsbergen and Loppa High. Fulltekst i vitenarkiv Vis sammendrag

  The Carboniferous in West Barents Sea and Spitsbergen is dominated by grabens and half graben segments linked in lateral extensive rifts with NE-SW-, NNE-SSW- and N trending axes. Timing of syn-rift activity and polarity shift of the master faults vary among the segments. In Svalbard and the Barents Sea: 1) Early to Middle Mississippian (Tournaisian to mid Visean) and 2) Late Mississippian to Mid Pennsylvanian (Serpukhovian/late Visean, to “mid” Moscovian activity is commonly observed. Parts of the segmented rift record both events as documented in the Nordkapp Basin and Bjørnøya, while other parts record only one, most commonly the youngest, as seen in the Billefjorden Trough, Spitsbergen and on Loppa High, Barents Sea. Regional rifting usually involve volcanic activity, and it is therefore surprising that no major occurrences of volcanics are associated with regionally important Carboniferous rift phases. Here, we present radiometric ages of Carboniferous volcanic rocks from the western margin of the Barents Platform and north-central Spitsbergen that indicate volcanic activity during initiation of the late Mississippian to Mid Pennsylvanian rift phase (2). At the crest of the Loppa High, Barents Sea, well 7120/2-1 reveals a near 700 m thick succession of multi coloured arkosic breccias, conglomerates, tephra, possible ignimbrites and volcanoclastics. Palynology of the succession gives a late Visean to early Serpukhovian age and it is assigned to the Billefjorden Group. The well terminates in a 31.5 m thick dolerite from 3471 m to total depth (TD) of 3502,5m RKB. Zircons from a sample at 3479.4m RKB were analysed by LA–ICP–MS (Laser ablation Inductively Coupled Mass Spectrometry) and yield a Concordia age of 333 ± 5 Ma (MSWD = 0.14); corresponding to a latest Visean to earliest Serpukhovian age. The 700m thick succession with volcanoclastic and pyroclastic rocks and the intrusion suggest a local volcanic centre near or on the Loppa High, i.e., on the northwards-trending rift axis. At Krosspynten in inner Wijdefjorden, central northern Spitsbergen, a north-south trending monchiquite (lamprophyre) dyke intrudes Lower Devonian sandstone of the Wood Bay Formation. The lamprophyre dyke was interpreted to represent localised E-W extension in connection with the development “mid” Carboniferous Billefjorden Trough and dated in 1964 to a K–Ar age of 309 +/-5 Ma (Moscovian). However, renewed sampling of the dyke in 2018 and application of the 40Ar/39Ar step-heating method indicates an age of 333.13 +- 0.98 MP, i.e., late Visean age. The Visean-Serpukhovian boundary volcanic rocks on Loppa High and at Krosspynten represent initial rift volcanism. Further geochemical studies and dating will enlighten the nature of the Carboniferous extensional phase in this part of the Arctic and probably link it as precursor of the breakup of the Pangea.

• Knarud, Ragnar; Mørk, Atle; Nakrem, Hans Arne & Olaussen, Snorre (2022). David Worsley (1943-2022). Geonytt. ISSN 0802-6173. 27(2), s. 14–17. Fulltekst i vitenarkiv
• Smyrak-Sikora, Aleksandra Anna; Blinkenberg, Kasper H.; Braathen, Alvar; Janocha, Julian; Johannessen, Erik Petter & Mosociova, Tereza [Vis alle 11 forfattere av denne artikkelen] (2022). Carboniferous - Permian rift systems in Svalbard. Fulltekst i vitenarkiv
• Stemmerik, Lars; Olaussen, Snorre & Braathen, Alvar (2022). Late Permian-Early Triassic synrift basin fill: Breakup of Pangea and the first brick in the puzzle of NE Atlantic-Arctic Mesozoic-early Cenozoic continental extension. Fulltekst i vitenarkiv
• Haile, Beyene Girma; Line, Lina Hedvig; Klausen, Tore Grane; Olaussen, Snorre; Eide, Christian Haug & Jahren, Jens [Vis alle 7 forfattere av denne artikkelen] (2021). Identifying and constraining sedimentary recycling from microscopic fluid inclusions in quartz overgrowth. Fulltekst i vitenarkiv
• Park, Juni; Stein, Holly J.; Hannah, Judith L.; Georgiev, Svetoslav; Yang, Gang & Hammer, Øyvind [Vis alle 7 forfattere av denne artikkelen] (2021). Re-Os geochronology of black shale from Central Spitsbergen, Svalbard: a stepping stone toward establishing the age of the J/K boundary. Fulltekst i vitenarkiv Vis sammendrag

  Stage boundaries are determined by integrating bio-, magneto-, and chrono-stratigraphic units. Numerical ages of stage boundaries ideally should be constrained or verified by reliable radiometric ages of sedimentary strata – a challenging task in the absence of ash layers suitable for U-Pb zircon dating. For example, the numerical age of the Jurassic – Cretaceous (J/K) boundary is still uncertain. Recent efforts provided some ammonite biostratigraphy across the J/K boundary in the Slottsmøya Member of the Agardhfjellet Formation on Spitsbergen. However, the age and duration of the uppermost Jurassic (Volgiann stage) and the lowermost Cretaceous (Ryazanian stage) in the Boreal realm remain loosely defined. Our study adds new radiometric ages for this controversial stage boundary and presents geochemical data to evaluate paleoenvironmental settings. Three black shale intervals from two drill cores (DH2 and DH5) located ~7 km apart in Central Spitsbergen provide three Re-Os ages. In DH2, shales from the Slottsmøya Member previously provided conflicting biostratigraphic results (Volgian toRyazanian)[1]. An isochron derived from samples at 497m depth yields an imprecise 146.8 ± 6.8 Ma age, suggesting deposition in the Upper Volgian rather th precludes confirmation. Large uncertainties near the J/K boundary are typical for this region[2, 3]. Two Re-Os isochron ages from the Oppdalen Member (DH2 at 724 and DH5 at 658 m) yield similar ages of 157.6 ± 3.3 Ma and 157.9 ± 2.9 Ma, respectively. These ages are close to the GTS Oxfordian – Kimmeridgian stage boundary and, even within their uncertainties, suggest Oxfordian – Kimmeridgian deposition. The agreement between these correlative intervals in the two cores[4] lends credence to the accuracy of the Re-Os age. Biostratigraphic data, however, suggest a somewhat older age. Seafloor erosion, reworking and redeposition, could create this discrepancy between geochronologic and biostratigraphic age determinations. Given that biostratigraphy between the Boreal and Tethyan realms is poorly correlated, the radiometric ages provided by this study could be a stepping stone toward better connecting the Boreal with the Tethyan realm. But further work, on all fronts, is needed. Acknowledgements. Thanks to the UNIS CO2 LAB for access to the drill cores. HS acknowledges the supportof ACS-PRF award # 59965-ND2. References: [1] Koevoets, M.J., Hammer, Ø. & Little, C.T.S. (2019). Norwegian Journal of Geology 99, 1-24. [2] Georgiev, S.V., Stein, H.J., Hannah, J.L., Xu, G.,Bingen, B., & Weiss, H.M. (2017). EPSL, 461, 151-162. [3] Markey, R., Stein, H.J., Hannah, J.L., Georgiev,.V., Pedersen, J.H., & Dons, C.E.(2017). Palaeogeography, Palaeoclimatology, Palaeoecology, 466, 209-220. [4] Koevoets, M.J., Abay, T.B., Hammer, Ø., & Olaussen, S. (2016). Palaeogeography, Palaeoclimatology, Palaeoecology, 449, 266-274

• Dahlin, Anders; Olaussen, Snorre; Smyrak-Sikora, Aleksandra; Stemmerik, Lars & Braathen, Alvar (2021). Late Palaeozoic syn-rift basin fill at the Sørkapp-Hornsund High, Southern Spitsbergen. Fulltekst i vitenarkiv
• Olaussen, Snorre; Grundvåg, Sten-Andreas; Hurum, Jørn Harald & Senger, Kim (2021). Back when the dinosaurs were ash-stranded. Appell. ISSN 0804-7758. Fulltekst i vitenarkiv
• Olaussen, Snorre; Larsen, Bjørn Tore & Dahlgren, Sven (2021). Late Carboniferous deposits in the Oslo Graben – a regional overview. Fulltekst i vitenarkiv
• Dahlin, Anders; Smyrak-Sikora, Aleksandra; Blinkenberg, Kasper; Olaussen, Snorre & Stemmerik, Lars (2021). Digital outcrop models of Upper Paleozoic mixed carbonate-siliciclastic deposits, Svalbard, Arctic Norway: Strengths and challenges. Fulltekst i vitenarkiv
• Serck, Christopher Sæbø; Poyatos-Moré, Miquel; Midtkandal, Ivar; Braathen, Alvar; Olaussen, Snorre & Osmundsen, Per Terje [Vis alle 7 forfattere av denne artikkelen] (2021). Tectonic basins around basement domes, Oman II. Fulltekst i vitenarkiv
• Würtzen, Camilla Louise; Smyrak-Sikora, Aleksandra; Janocha, Julian; Johannesen, Erik; Olaussen, Snorre & Stemmerik, Lars (2021). Facies variability of the continental Lower Carboniferous Billefjorden Group in Central Spitsbergen, Svalbard. Fulltekst i vitenarkiv
• Smyrak-Sikora, Aleksandra; Braathen, Alvar; Janocha, Julian; Johannessen, E.P.; Lord, Gabriel & Olaussen, Snorre [Vis alle 8 forfattere av denne artikkelen] (2020). On-offshore correlations of the Billefjorden Fault Zone, Svalbard. Fulltekst i vitenarkiv
• Smyrak-Sikora, Aleksandra; Braathen, Alvar; Julian, Joshua Benjamin; Johannessen, E.P.; Lord, Gabriel & Olaussen, Snorre [Vis alle 9 forfattere av denne artikkelen] (2020). How digital outcrop analysis enhances understanding of rift basin architecture (Billefjorden Trough Svalbard)? Fulltekst i vitenarkiv
• Olaussen, Snorre; Grundvåg, Sten-Andreas; Hurum, Jørn Harald & Senger, Kim (2020). Den gangen dinosaurene var askefaste. Svalbardposten. Fulltekst i vitenarkiv
• Würtzen, Camilla Louise; Stemmerik, Lars; Olaussen, Snorre & Ahokas, Juha Matti (2019). Facies analysis of the Uppermost Devonian to Lower Carboniferous Billefjorden Group, Central Spitsbergen, Svalbard. Fulltekst i vitenarkiv
• Grundvåg, Sten-Andreas; Olaussen, Snorre; Midtkandal, Ivar & Sliwinska, Kasia (2019). On the trace of a lower Aptian source rock in Svalbard. Fulltekst i vitenarkiv
• Abay, Tesfamariam Berhane; Karlsen, Dag Arild; Olaussen, Snorre & Pedersen, Jon Halvard (2019). Organic Geochemistry of Petroleum in the Cambro-Ordovician Succession of Ny Friesland, Spitsbergen, Norway. Fulltekst i vitenarkiv
• Senger, Kim; Brugmans, Peter; Grundvåg, Sten-Andreas; Jochmann, Malte Michel; Nøttvedt, Arvid & Olaussen, Snorre [Vis alle 8 forfattere av denne artikkelen] (2019). Petroleum Exploration Onshore Svalbard: A Historical Perspective on the Start of the Norwegian Oil Adventure. Fulltekst i vitenarkiv
• Grundvåg, Sten-Andreas; Senger, Kim; Larssen, Geir Birger; Olaussen, Snorre & Riis, Fridtjof (2019). Late Jurassic – Early Cretaceous sedimentary response to opening of the Amerasian Basin and HALIP activity in Svalbard. Fulltekst i vitenarkiv Vis sammendrag

  The Upper Jurassic to Lower Cretaceous succession in Svalbard consists of two prominent clastic wedges that prograded in a general southeastward (and later also southwestward) direction in response to recurrent uplift of northern Svalbard and adjacent terranes from the Late Jurassic onwards (Fig. 1A). A strong HALIP signal is well known from the Lower Cretaceous part of the succession. Numerous dolerite intrusions of Early Cretaceous age (Fig. 1B) are present across the entire outcrop belt (with sills predominantly penetrating Permian to Triassic strata) and in nearby offshore areas as revealed by reflection seismic data east and south of Svalbard. Bentonites occur locally as documented in onshore research boreholes. Previously published absolute datings of several intrusions and one bentonite bed yields ages in the range of 123.3–124.7 Ma, pointing to peak HALIP activity in the earliest Aptian. In addition, a regional provenance switch from quartz arenites to plagioclase-rich lithic arenites and volcanic clasts is evident in the Barremian–Aptian part of the succession (Fig. 1C, D, E). In eastern Spitsbergen, paleo-current directions also indicate an emerging provenance area to the NE. Further east at Kong Karls Land, basaltic lava flows occur interbedded with paralic deposits of late Barremian to Aptian age. Collectively, this indicate significant HALIP influence on the sedimentary system in Svalbard during the Early Cretaceous. Less known is the tectono-sedimentary response directly related to the opening of the Amerasian Basin, which pre-dates the short-lived HALIP activity. Several regional unconformities occur in the Upper Jurassic–lowermost Cretaceous succession, including the Oxfordian, the Volgian to lowermost Ryazanian, and the lower Barremian unconformities (Fig. 1A). Although the development and exact timing of the two former unconformities is yet to be investigated, the latter is commonly attributed to regional upwarping and southeastward tilting prior to the main HALIP pulse. Shallow marine and shelf sandstone units in the Upper Jurassic–lowermost Cretaceous succession typically pinch out to the SE, thus indicating a clear northwestern provenance area. We suggest that these sandstone units may record the initial sedimentary response to rift-shoulder uplift during opening of the Amerasian Basin north of Svalbard.

• Olaussen, Snorre; Varela, Alejandro Escalona; Grundvåg, Sten-Andreas; Restrepo, Dora Luz Marin; Ohm, Sverre Ekrene & Senger, Kim (2019). Middle Jurassic to Lower Cretaceous Clastic Wedges in the north Atlantic, Barents Sea and High Arctic. Fulltekst i vitenarkiv
• Olaussen, Snorre; Varela, Alejandro Escalona; Grundvåg, Sten-Andreas; Restrepo, Dora Luz Marin; Senger, Kim & Ohm, Sverre Ekrene (2019). Middle Jurassic to Lower Cretaceous Clastic Wedges in the north Atlantic, Barents Sea and High Arctic. Fulltekst i vitenarkiv
• Würtzen, Camilla Louise; Stemmerik, Lars; Olaussen, Snorre & Ahokas, Juha Matti (2018). Facies analysis of the uppermost Devonian to Lower Carboniferous Billefjorden Group, Central Spitsbergen, Svalbard. Fulltekst i vitenarkiv
• Olaussen, Snorre & Rismyhr, Bjarte (2018). Large scale tectonics as controlling factor of the Upper Triassic to Middle Jurassic basin fills in Svalbard and nearby pan‐Arctic Basins. Fulltekst i vitenarkiv
• Olaussen, Snorre; Larssen, Geir Birger; Helland-Hansen, William; Johannessen, Erik P.; Nøttvedt, Arvid & Riis, Fridtjof [Vis alle 9 forfattere av denne artikkelen] (2018). The outcropping strata in the Kong Karls Land archipelago, Arctic Norway; a key reference point for the Upper Triassic to Lower Cretaceous succession in the northern Barents Sea. Fulltekst i vitenarkiv
• Birchall, Thomas; Senger, Kim & Olaussen, Snorre (2018). Subnormal Pressure Regimes of the Northern Barents Shelf: Causes and Implications for Hydrocarbon Exploration. Fulltekst i vitenarkiv
• Koehl, Jean-Baptiste P.; Bergh, Steffen G; Henningsen, Tormod; Faleide, Jan Inge; Smyrak-Sikora, Aleksandra & Olaussen, Snorre [Vis alle 7 forfattere av denne artikkelen] (2018). Mid/Late Devonian-early Carboniferous collapse basins in the Barents Sea and Svalbard. Fulltekst i vitenarkiv
• Olaussen, Snorre; Larssen, Geir Birger; Helland-Hansen, William; Johannessen, Erik P.; Nøttvedt, Arvid & Riis, Fritjof [Vis alle 9 forfattere av denne artikkelen] (2018). The outcropping strata in Kong Karls Land archipelago, Arctic Norway; a key reference point for the Upper Triassic to Lower Cretaceous succession in the northern Barents Sea. Fulltekst i vitenarkiv
• Senger, Kim; Farnsworth, Wesley Randall; Christiansen, Hanne H; Gilbert, Graham Lewis; Hancock, Holt John & Hodson, Andrew J. [Vis alle 16 forfattere av denne artikkelen] (2018). Field-based geology education in the high Arctic: How digital tools can support active learning. Fulltekst i vitenarkiv
• Olaussen, Snorre; Grundvåg, Sten-Andreas; Senger, Kim; Birchall, Thomas & Smyrak-Sikora, Aleksandra (2018). Understanding Barents Sea Play Concepts Based on 18 wildcats, and some R&D wells, in Svalbard. Fulltekst i vitenarkiv
• Olaussen, Snorre; Senger, Kim; Birchall, Thomas; Braathen, Alvar; Grundvåg, Sten-Andreas & Hammer, Øyvind [Vis alle 13 forfattere av denne artikkelen] (2018). The Longyearbyen CO2 lab project: lessons learned from a decade of characterizing an unconventional reservoir-caprock system. Fulltekst i vitenarkiv
• Lord, Gareth Steven; Mørk, Atle & Olaussen, Snorre (2017). Sequence stratigraphy and facies development of the Triassic succession of Svalbard and the northern Barents Sea. Norges teknisk-naturvitenskapelige universitet. ISSN 9788232624645. Fulltekst i vitenarkiv Vis sammendrag

  The Triassic succession of Svalbard is regarded as an analogue to the subsurface in the Barents Sea. In this thesis the sedimentology, facies development and sequence stratigraphy of the succession in Svalbard is addressed. The project has resulted in 4 journal articles, a submitted manuscript and a manuscript in preparation. A geological map has also been produced. The project has created a new stratigraphic unit the Hopen Member, which is the south-eastern equivalent to the Isfjorden Member of Spitsbergen. This is based on the properties of the unit, its biostratigraphic and magnetostratigraphic characteristics. The Hopen Member is a succession of marine shale and subordinate sandstone deposits, different to the paralic deposits of the underlying part of the De Geerdalen Formation. A study of channel bodies on Hopen shows they are confined to discrete stratigraphical intervals in the De Geerdalen Formation, defined as channel zones. Three zones are described and categorised as; a lower fluvial, middle tidal zone and upper fluvial zones. A paralic depositional environment for the De Geerdalen Formation on Hopen is maintained, however the nature of channels shows a greater influence of fluvial deposition, for the formation in this part of Svalbard. A multidisciplinary study of the Kapp Toscana Group (De Geerdalen, Flatsalen and Svenskøya formations) on Hopen is also presented and this provides an enhanced palaeo-environmental interpretation for the Upper Triassic succession on the island. Upper Triassic deltaic sediments are seen throughout north-eastern Svalbard and analysis shows the De Geerdalen Formation to consist of three discrete informal units, defined by the gross depositional environment. The lower interval is dominated by shallow marine and delta front / shoreface deposits, the middle interval is composed of delta front to delta top deposits, and the upper interval is primarily delta top, lagoonal and lacustrine deposits. The De Geerdalen Formation represents a distal depositional setting in this area, in comparison to the depositional environments reported on the islands of Edgeøya and Hopen. A facies study, conducted on the Svenskøya Formation in Eastern Svalbard, interprets the formation to be composed of sandstones deposited in a mixed fluvial, shoreface and shallow marine setting. Petrographic analysis of sandstones shows the formation as being arkosic, on Hopen and in the Sentralbanken area. The sandstone reservoir quality at Hopen is reduced compared to Sentralbanken, due to more extensive diagenetic impacts by compaction, mineral dissolution and extensive precipitation of pore-filling clay minerals. Similar properties are observed on Wilhelmøya and Kong Karls Land. A regional study into the sequence development of the Triassic succession in Svalbard is the final component to this project. Analysis shows an increase in the number of low rank sequences in the western area of Svalbard, compared with central and eastern areas, in the Lower and Middle Triassic succession. This is due to the style of facies development, close to the basin margin at that time. The Upper Triassic shows the opposite trend, with an increase in low ranking sequences towards the east of Svalbard. Offshore the entire succession thickens as a result of deltaic development in these areas.

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