Norwegian Barents Sea Research Articles

Geological and glaciological controls of 21,700 active methane seeps in the northern Norwegian Barents sea

Geological and glaciological controls of 21,700 active methane seeps in the northern Norwegian Barents sea

Time-calibration of carbonate diagenesis and regional tectonism in the Norwegian Barents Sea

Diagenesis plays a crucial role in carbonate reservoir properties, for example through the dissolution or precipitation of carbonate minerals, with burial history and fluid migration thought to play an important role in the timing of these events. To better understand these relationships and the local manifestation of regional events, we study carbonate sedimentary rocks and associated diagenetic cements from the Loppa High and Finnmark Platform using in-situ U–Pb carbonate geochronology and C–O stable isotope ratios, combined with burial history modelling. The results indicate a complex history of diagenesis: analyzed dolomicrite samples from the Loppa High typically yield ages that are older than their biostratigraphic age, in contrast to dolomicrite samples from the Finnmark Platform that yielded younger ages; this regional offset may be reflective of different styles of early diagenesis, as well as heterogeneous and re-deposited origin of some studied materials. While many diagenetic calcite cements coincide with modelled burial or uplift events, other events have no cements associated with them, although the possibility that some diagenetic carbonate phases were unsampled cannot be ruled out. Some calcite cements are not associated with burial events at all and may instead be related to hydrocarbon ‘charging’, supported by strongly negative δ13C values recorded in these cements. Broadly, these results highlight the value of integrating petrographic observations, burial history modelling, carbonate U–Pb geochronology, and C–O isotope ratios, as well as the complexity of untangling diagenetic histories.

Kola-Kanin Monocline Composite Tectono-Sedimentary Element, Barents Sea

Abstract Kola-Kanin Monocline Composite Tectono-Sedimentary Element (KKM CTSE) is located in the Eastern Barents Sea offshore the Kola Peninsula. Tectonically it represents a SW rim of the East Barents Basin, one of the largest sedimentary depocentres in the Arctic. It is also an apparent SE continuation of the Finnmark Platform in the Norwegian Barents Sea; however, there are some differences between them in tectonic history and stratigraphy. The KKM is inferred to include Lower Paleozoic sedimentary rocks. These are not present in the Finnmark Platform due to the Caledonian orogeny. The younger section includes Devonian to Lower Permian siliciclastic and carbonate rocks, Permian-Triassic, Jurassic, and Lower Cretaceous siliciclastic strata. The entire sedimentary section is up to 10 km thick and is divided into three main successions, or tectono-sedimentary elements (TSE): (i) Syn-rift upper Cambrian to lower Ordovician, (ii) Middle Ordovician to Lower Triassic passive margin, and (iii) Middle Triassic to Lower Cretaceous (Albian) intracontinental basin. The KKM represents a potential region for the hydrocarbon exploration, but numerous prospects identified there have not been drilled due to significant exploration risks caused by the monoclinal dip and erosional truncation of the most of the KKM's section.

An agent-based modelling framework for performance assessment of search and rescue operations in the Barents Sea

In recent years, the increase in Arctic offshore activities has raised concerns about the search and rescue (SAR) operations as mitigative measures to ensure the safety of shipping and cruise activities. Performing SAR operations in the remote Arctic offshore environment is exceptionally challenging due to the severe environmental conditions, including low temperatures, high waves, strong winds, heavy snow showers, sea ice, spray icing, dense fog, limited visibility, and polar low pressures. Moreover, the scarcity of port infrastructure along the Arctic coastline exacerbates the difficulties faced during SAR operations. Tackling the aforementioned challenges necessitates a comprehensive modelling framework for analysis of SAR operations in the Arctic that is able to consider the dynamics and uncertain nature of Arctic harsh environmental conditions, and the constraints imposed by the limited capacity of Arctic SAR infrastructure. To this aim, this paper proposes an agent-based modelling (ABM) framework to assess the performance of SAR operations while tackling such challenges in the Arctic. A Monte Carlo simulation approach is used to model the dynamics and uncertainty of weather and sea conditions using historical data, using which some severity levels are determined. Expert judgement process is then used quantify the impacts of such severity levels on the performance of rescue agents, and thus, on the total rescue time. To validate the proposed framework, an illustrative case in the Norwegian Barents Sea is considered, where the performance of SAR infrastructure is examined under different rescue scenarios. According to the results of this paper, the total rescue time is the longest during December to February, and the shortest rescue time is associated with months May to August. Some recommendations are further proposed to improve the performance of SAR infrastructure in the Barents Sea.

How the spatio-temporal overlap of cod, haddock, and capelin larvae affects their recruitment in the Norwegian-Barents Sea system

How the spatio-temporal overlap of cod, haddock, and capelin larvae affects their recruitment in the Norwegian-Barents Sea system

The effects of uplift and erosion on the petroleum systems in the southwestern Barents Sea: Insights from seismic data and 2D petroleum systems modelling

In the past three decades, the hydrocarbon prospectivity has been enigmatic in the southwestern Barents Sea as gas discoveries have dominated over oil. However, more recent discoveries indicate oil potential, especially in the Polheim Platform and Hoop Complex areas. Cenozoic uplift and erosion episodes are critical because they control the duration and depth of maximum burial of source rocks and the reduction of porosity of reservoir rocks due to diagenetic processes at larger depth and increased temperatures. Modelling of interpreted horizons from the southwestern Barents Sea provide a best-fit realization of the basin-scale sedimentary filling from the post-rifting in the Jurassic until the Last Glacial Maximum. 2D basin modelling was performed across one regional seismic section crossing the southwestern Barents Sea. For calibration of the 2D model, 1D modelling was performed for a selected number of wells in the region by integrating different estimates of net apparent erosion (velocity inversion of wells, interpreted profiles and structure maps as well as from temperature and vitrinite reflectance data) in order to assess the burial, thermal and maturity history of the source rocks at various well locations as well as along the 2D profile. Simulation results show that the Upper Jurassic source rock is immature to marginal mature in the central and eastern parts of the Norwegian Barents Sea. The western part is characterised by high chargeability of traps associated with rich source kitchens and porous reservoir rocks. Although not proven by commercial discoveries, there are evidences that the Permian Ørret and the Lower-Middle Triassic basal Klappmyss and basal Kobbe shales may be important gas-prone source rocks in the eastern Norwegian Barents Sea. Consequently, the exploration must rely on the Triassic and/or Palaeozoic source rocks in the eastern area.

Implications of transient methane flux on associated biological communities in high-arctic seep habitats, Storbanken, Norwegian Barents Sea

The continental margins of the Arctic Ocean basin contain methane seeps, where transient fluxes of seafloor methane are released due to the thermal dissociation of gas hydrates. An increase in shallow methane seeps identified over the past decade, potentially due to enhanced warming of the Arctic Ocean bottom water and associated destabilization of hydrate structure. Biological communities associated with methane release east of Svalbard in the Barents Sea (Storbanken Crater site, 76° 46.7′N, 35° 43.5′E, depths between 120 m–300 m depths) were investigated using towed camera imagery and ship-based platforms during a 2017 CAGE17-2 cruise on the RV Helmer Hanssen. We analyzed relationships among methane flux data, seafloor habitat characteristics, and biological community structure (i.e., presence and distribution of megafauna and expression of microbial mats) from a total of 14 surveys (6827 images and 40 multicore sediment cores) within the Storbanken Crater area and compared it to 2015 data. Unlike seep expressions at deeper sites (∼1200 m) in the Norwegian margin region, no seep-endemic, chemosynthetic-associated megafaunal species were observed at the shallow surveyed sites and all sites hosted similarly diverse communities of non-seep species, including commercially important fish and crustaceans. Methane concentrations did not markedly differ between the crater and non-crater sites. Rates of methane gas advection through sediments (in the form of flares) were relatively low and concentration of methane was even lower in porewater samples at the crater site. We present the first evidence of methane flare flux and intermittent microbial mat distribution with associated folliculinid ciliates, which suggests a long history of methane emissions and a transient seep environment in spatial and temporal flux. Together, this study presents a critical baseline on the temporal release of arctic methane and benthic biological communities to initiate temporal studies that identify future changes and predict the impact of climate change.

The Barents and Norwegian Seas beaked redfish (Sebastes mentella): stock assessment and fishery management

An analytical review of the stock assessment and fishery regulation of the Barents and Norwegian Seas beaked redfish is presented. Model estimates of stock dynamics are characterized by uncertainty associated with incomplete coverage of the beaked redfish distribution in surveys, age determination problems, and assumptions made in the model. The regulation of fishing mortality is based on the precautionary approach, and the main management aim is achievement of the maximum sustainable yield. Technical measures include limiting the minimum mesh size in the trawl, establishing a minimum fish length for fishery, temporal fishery closures and limiting by-catch in multi-species fisheries. The unregulated fishery of the Norwegian-Barents Sea beaked redfish in the 1970s was one of the reasons for the decline in its stock and appearance of poor recruitment, which led to the ban on its targeted fishing in the Norwegian Economic Zone and in the fish protection area of the Svalbard. In 2014, the fishing was reopened. At present, the stock of beaked redfish of the Norwegian-Barents Sea population is in a safe state and further growth of the catch is expected.

Timanian Fold-and-Thrust Belt and Caledonian Overprint in the Selis Ridge Imaged by New 3D Seismic Attributes and Spectral Decomposition

The present study is a detailed structural analysis of 3D seismic data in the Selis Ridge in the western Loppa High in the Norwegian Barents Sea, to which new seismic attributes and spectral decomposition were applied. The analysis reveals that pre-Devonian basement rocks are crosscut by a 40–50 kilometers wide, several kilometers thick, E–W- to WNW–ESE-striking fold-and-thrust belt, including a steep, kilometer-thick, top-SSW shear zone. The folds display dome- and trough-shaped geometries, the thrusts appear to have been reactivated dominantly as top-west structures, and the main shear zone warps over the top of the Selis Ridge. The fold-and-thrust belt is interpreted as part of the latest Neoproterozoic (ca. 650–550 Ma) Timanian Orogeny, which potentially reworked preexisting Neoproterozoic rift basins and highs, and was reworked during E–W Caledonian contraction in the Ordovician–Silurian. The results are analogous to recent findings in the northern Norwegian Barents Sea and Svalbard. The presented interpretation provides the basis for discussing Neoproterozoic–Paleozoic plate tectonics reconstructions, the influence of Precambrian–early Paleozoic structures on post-Caledonian fault complexes, the location of the Timanian and Caledonian suture zones, Neoproterozoic rifting, and the origin of the Seiland Igneous Province.

Hydrocarbons in Water and Bottom Sediments of the Norwegian–Barents Sea Basin

The distribution of hydrocarbons (HCs): aliphatic–AHCs and polycyclic aromatic hydrocarbons–PAHs is examined in waters and bottom sediments sampled during cruises 75 and 80 of the R/V Akademik Mstislav Keldysh in 2019 and 2020 in the Norwegian–Barents Sea Basin: Mohns Ridge, shelf of the Svalbard Archipelago, Storfjord, Medvezhinsky trench, central part of the Barents Sea, Novaya Zemlya shelf, and Franz Victoria Trough. An increase in AHCs content, on average, up to 20–23 μg/L in the suspended particulate matter (SPM) in surface waters compared to those of 2016–2017 is caused by phytoplankton bloom near the ice edge. In bottom sediments, the distribution of AHCs (3–186 μg/g) and PAHs (3–9934 ng/g) depends not only on the sedimentation conditions and particle size composition of sediments, but also on the variability of redox conditions in the sedimentary sequence and molecular diffusion of HCs from productive horizons.

Hydrocarbons in Water and Bottom Sediments of the Norwegian–Barents Sea Basin

Hydrocarbons in Water and Bottom Sediments of the Norwegian–Barents Sea Basin

Lost in Translation – Following the Ecosystem Approach from Malawi to the Barents Sea

New ideas are constantly being produced as a changing world demands solutions to new problems. International environmental regimes often present ideas to reduce negative human effects on the environment. Implementation of ideas has often been studied through diffusion theory, where ideas are expected to be implemented in their original version. Translation theory from New Scandinavian Institutionalism allows for an analysis of how ideas invented to solve problems change from introduction to implementation. Ideas heralded through UN processes may face a very long route from introduction to local implementation, during which the idea can become radically changed. Through a thorough study of documents, this article follows the trajectories of the idea of Ecosystem Approach (EA), from its first limited practical application in the US during the 1980s and 90s, during its travels in different United Nations fora, and ending up implemented locally through the 2006 Norwegian Barents Sea Management Plan. The novelty of this study is that the analyses cover a long timeframe combined with a focus on all the different steps of translation combined. This also allows for possible drivers of change to be identified. The results show that there are changes made to the idea to such an extent that what is finally implemented is something quite different from the original idea, and more like “business as usual”. According to the theory, discrepancies do not necessarily mean the idea has not been successful; on the contrary, ideas that can be changed may be more likely to become institutionalized.

CAGE22-6 cruise report: GEO-3144/8144 Teaching Cruise: Geologically controlled hydrocarbon seepage in Hopendjupet and the wider Barents Sea

The CAGE22-6 cruise on-board R/V Helmer Hanssen hosted UiT´s Arctic Marine Geology and Geophysics (GEO-8144 and GEO-3144) field course for PhD and Master students, and was carried out in collaboration with NPD – the Norwegian Petroleum Directorate and the INTPART project HOTMUD based at Centre for Earth Evolution and Dynamics (CEED) the University of Oslo. The cruise was also a part of the UNESCO Training Through Research program (formerly, The Floating University) and in the framework of this project is also coded as TTR22. The main scientific objectives of the cruise were to investigate: geological controls on fluid-flow dynamics on an uplifted, repeatedly glaciated, and eroded Northern Norwegian Barents Sea shelf and, the fate of the released hydrocarbons in the water column, on the sea surface, and in the atmosphere. The cruise may be known as: CAGE22_6

Shaking and splashing—A case study of far‐field effects of the Mjølnir asteroid impact on depositional environments in the Barents Sea

AbstractThe Mjølnir impact crater in the Norwegian Barents Sea features among the 20 largest impact craters listed in the Earth Impact Database. The impact is dated to 142 ± 2.6 Ma, corresponding closely to the Jurassic/Cretaceous boundary in the Boreal stratigraphy. Multidisciplinary studies carried out over the last three decades have suggested that the up to 40 km wide crater was created by a 1–3 km diameter impactor colliding with a shallow epicontinental sea, causing regional havoc and a regional ecological crisis that followed in its wake. Only minor evidence for the consequences of the impact for the surrounding depositional basins has been documented so far. This study describes a large submarine slump penetrated by hydrocarbon exploration well 7121/9‐1, located in the southern Hammerfest Basin and approximately 350 km away from the impact site. The slump is dated by a black shale drape, which contains characteristic impact‐related biotic assemblages and potential ejecta material. This precise dating enables us to associate the slump with large‐scale fault movements and footwall collapse along the basin‐bounding Troms‐Finnmark Fault Complex, which we conclude were caused by shock waves from the Mjølnir impact and the passage of associated tsunami trains. The draping black shale is interpreted to represent significant reworking of material from the contemporary seabed by tsunamis and currents set up by the impact.

Loppa High Composite Tectono-Sedimentary Element, Barents Sea

Abstract The Loppa High Composite Tectono-Sedimentary Element is a mature exploration area in the south-western Norwegian Barents Sea hosting Skrugard (2012) and the Late Paleozoic Gohta (2013) discoveries. The exploration of the Loppa High started in 1985, and today this is the most studied area of the Barents Shelf which subsurface mapping is based on dense coverage of modern 3D and 2D seismic data and drilling results of over 40 exploration wells. This chapter summarizes the tectono-sedimentary and sub regional development and the petroleum geology of the Loppa High.

Impact of Timanian thrust systems on the late Neoproterozoic–Phanerozoic tectonic evolution of the Barents Sea and Svalbard

Abstract. The Svalbard Archipelago consists of three basement terranes that record a complex Neoproterozoic–Phanerozoic tectonic history, including four contractional events (Grenvillian, Caledonian, Ellesmerian, and Eurekan) and two episodes of collapse- to rift-related extension (Devonian–Carboniferous and late Cenozoic). Previous studies suggest that these three terranes likely accreted during the early to mid-Paleozoic Caledonian and Ellesmerian orogenies. Yet recent geochronological analyses show that the northwestern and southwestern terranes of Svalbard both record an episode of amphibolite (–eclogite) facies metamorphism in the latest Neoproterozoic, which may relate to the 650–550 Ma Timanian Orogeny identified in northwestern Russia, northern Norway, and the Russian Barents Sea. However, discrete Timanian structures have yet to be identified in Svalbard and the Norwegian Barents Sea. Through analysis of seismic reflection, as well as regional gravimetric and magnetic data, this study demonstrates the presence of continuous thrust systems that are several kilometers thick, NNE-dipping, deeply buried, and extend thousands of kilometers from northwestern Russia to northeastern Norway, the northern Norwegian Barents Sea, and the Svalbard Archipelago. The consistency in orientation and geometry, as well as apparent linkage between these thrust systems and those recognized as part of the Timanian Orogeny in northwestern Russia and Novaya Zemlya, suggests that the mapped structures are likely Timanian. If correct, these findings would imply that Svalbard's three basement terranes and the Barents Sea were accreted onto northern Norway during the Timanian Orogeny and should hence be attached to Baltica and northwestern Russia in future Neoproterozoic–early Paleozoic plate tectonics reconstructions. In the Phanerozoic, the study suggests that the interpreted Timanian thrust systems represent major preexisting zones of weakness that were reactivated, folded, and overprinted by (i.e., controlled the formation of new) brittle faults during later tectonic events. These faults are still active at present and can be linked to folding and offset of the seafloor.

The porosity preserving effect of basin wide illitic coating in deeply buried sandstone intervals of the lower Jurassic Stø Formation, Barents Sea

The Stø Formation contains the main target reservoirs for petroleum exploration in the Norwegian Barents Sea Area, however, the clean sandstones of the Stø Formation can be heavily quartz cemented in areas that have undergone extensive post depositional burial. The Stø Formation in well 7219/8-2 has previously been identified as having porosities well above the expected porosity depth trend due to the porosity preserving effects of illitic grain coating. In this study the Stø Formation in 14 wells with maximum burial depths at top of formation ranging from 2672 to 3623 m have been investigated and several new intervals of the formation show abnormally high porosities relative to the expected burial trend. Thin sections from 4 wells were available and in all of these remnants of grain coating illitic clay was observed in varying amounts, with the effectiveness in reducing quartz cement overgrowth being determined by the continuity of grain coats. This indicates that the degree of grain coating coverage exerts the main control on the porosity of the clean deeply buried parts of the Stø Formation. With increasing burial depths, the porosity difference between intervals with continuous grain coats and intervals with less continuous grain coats becomes ever larger. Intervals observed to have extensive grain coating coverage compact with a significantly reduced rate with increasing burial compared to poorer coated intervals in the chemical compaction domain. The noticeable and consistent difference in the chemical compaction trend between coated- and negligible coated intervals within the Stø Formation could allow for establishment of powerful predictive models without the need for expensive petrographic- or core plug data.

Finnmark Platform Composite Tectono-Sedimentary Element, Barents Sea

Abstract The Finnmark Platform Composite Tectono-Sedimentary Element (CTSE), located in the southern Barents Sea, is a northward-dipping monoclinal structural unit. It covers most of the southern Norwegian Barents Sea where it borders the Norwegian mainland. Except for the different age of basement, the CTSE extends eastwards into the Kola Monocline on the Russian part of the Barents Sea. The general water depth varies between 200 and 350 m, and the sea bottom is influenced by Plio-Pleistocene glaciations. A high frequency of scour marks and deposition of moraine materials exists on the platform areas. Successively older strata sub-crop below the Upper Regional Unconformity (URU), which was formed by several glacial periods. Basement rocks of Neoproterozoic age were heavily affected by the Caledonian Orogeny, and previously by the Timanide tectonic compression in the easternmost part of the Finnmark Platform CTSE. Depth to crystalline basement varies considerably and is estimated to be from 4–5 to 10 km. Following the Caledonian orogenesis, the Finnmark Platform was affected by Lower–Middle Carboniferous rifting, sediment input from the Uralian Orogen in the east, the Upper Jurassic–Lower Cretaceous rift phase and the Late Plio-Pleistocene isostatic uplift. A total of eight exploration wells drilled different targets on the platform. Two minor discoveries have been made proving the presence of both oil and gas, and potential sandstone reservoirs of good quality identified in the Visean, Induan, Anisian and Carnian intervals. In addition, thick sequences of Permo-Carboniferous carbonates and spiculitic chert are proven in the eastern Platform area. The deep reservoirs are believed to be charged from Paleozoic sources. A western extension of the Domanik source rocks well documented in the Timan–Pechora Basin may exist towards the eastern part of the Finnmark Platform. In the westernmost part, charge from juxtaposed downfaulted basins may be possible.

Features of the Hydrocarbon Distribution in the Bottom Sediments of the Norwegian and Barents Seas

The results of the study of hydrocarbons (HCs): aliphatic (AHCs) and polycyclic aromatic hydrocarbons (PAHs) in bottom sediments (2019 and 2020, cruises 75 and 80 of the R/V Akademik Mstislav Keldysh) in the Norwegian-Barents Sea basin: Mohns Ridge, shelf Svalbard archipelago, Sturfiord, Medvezhinsky trench, central part of the Barents Sea, Novaya Zemlya shelf, Franz Victoria trough are presented. It has been established that the organo-geochemical background of the Holocene sediments was formed due to the flow of sedimentary material in the coastal regions of the Barents Sea on shipping routes. The anthropogenic input of HCs into bottom sediments leads to an increase in their content in the composition of Corg (in the sandy sediments of the Kaninsky Bank at an AHC concentration up to 64 μg/g, when its proportion in the composition of Corg reaches 11.7%). The endogenous influence on the of the Svalbard archipelago shelf in Sturfiord and in the Medvezhinsky Trench determines the specificity of local anomalies in the content and composition of HCs. This is reflected in the absence of a correlation between HCs and the grain size composition of sediments and Corg content, as well as a change in hydrocarbon molecular markers. At the same time, the sedimentary section is enriched in light alkanes and naphthalene’s that may be due to emission during point discharge of gas fluid from sedimentary rocks of the lower stratigraphic horizons and/or sipping migration.

Upper Jurassic to Lower Cretaceous source rocks in the Norwegian Barents Sea, part II: Insights from open- and closed-system pyrolysis experiments

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.