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Across the Norwegian Continental Shelf (NCS), the Upper Jurassic organic-rich shales are considered the main source rock unit charging most of the largest producing oil and gas fields. However, despite its extensive distribution across the NCS, this source rock unit is overmature and spent in the deep Cretaceous basins on the mid-Norwegian margin and the SW Barents Shelf. Documenting the presence of alternative source rock units at stratigraphic shallower intervals is therefore crucial for exploration success in these frontier areas. Such alternative source rock units may amongst others occur in the Lower Cretaceous or younger successions. The main objective of this study is thus to establish the presence, spatial variations, depositional conditions, and petroleum potential of Cretaceous organic-rich units on the NCS, particularly focusing on the deep Cretaceous basins along its rifted western margin. From south to north, the main study areas are confined to the mid-Norwegian margin (Paper II), the SW Barents Shelf (Paper I), and Svalbard (Paper III), the latter representing the exhumed NW corner of the NCS. This study utilizes high-quality regional 2D reflection seismic data, wireline logs, and an extensive geochemical database, all combined to assess and elucidate the petroleum potential of several organic-rich units recognized in the Lower Cretaceous of the study areas. This integrated dataset forms the basis for conceptual models made specifically for each region which host organic-rich units with generation potential. These models emphasize changing depositional conditions and factors that controlled the development and preservation of the various organic-rich units, including regional rift-related tectonics and global anoxic events. The lateral distribution of the organic-rich units is also discussed with respect to the regional tectonic evolution of the NCS during the Cretaceous, and their potential is established through traditional source rock evaluation.

The Norwegian Barents Shelf (NBS) is an Arctic petroleum province with a complex geological history. Current geochemical work on oil discoveries in the region has identified Triassic mudstones as important petroleum source rocks. A review of the published literature found that several source rock-forming processes have been suggested as contributors to their formation. The aim of this thesis is thus to further understand the paleoenvironmental factors that affected Triassic source rock formation and potential on the NBS. This was done by investigating the lithostratigraphy and organic/inorganic chemostratigraphy of the organic-rich Spathian–Carnian outcrops on Edgeøya, eastern Svalbard. These exposures represent uplifted and exhumed strata of the northwestern NBS that are equivalent to Triassic source rocks on the southern NBS. Paper I characterizes the mudstone facies and bulk organic properties of the Anisian–Ladinian Botneheia Formation to investigate benthic redox conditions, productivity, and organic richness. Paper II performs a multi-elemental chemostratigraphic analysis to further clarify how these environmental factors affected Spathian–Carnian source rock formation. Paper III documents source- and maturity-specific biomarker compounds of the investigated succession and their correlation with oils from the Alta, Gohta, Wisting Central and Hanssen discoveries on the NBS. These papers consider the reported climate-induced transition from warmer to cooler oceans at the Spathian–Anisian boundary to have an important impact on Spathian vs. Anisian–Ladinian source rock formation in the region. The early Carnian pro-deltaic mudstones terminated formation of oil-prone source rocks due to the prograding Triassic Boreal Ocean delta system in the south. Spathian mudstone extracts from Svalbard and the Spathian-sourced Wisting Central/Hanssen oils show strong biomarker correlations, indicating that these age-equivalent source rocks have comparable organic facies. This challenges the idea that Spathian mudstones on the southern NBS are lateral facies equivalents to the Anisian–Ladinian mudstones in Svalbard. These findings have important implications for conceptualizing the Lower–Upper Triassic source rock models on the NBS.

This thesis examined gas flares found in the Cruise log 20-2 from CAGE and correlated them to subsurface seismic data in south of Barents Sea. The cruise log passed several hydrocarbon discoveries/fields such as Goliat, Caurus/Langlitinden, Norvarg and Wisting/Hanssen. The aim of the thesis is to investigate the relationship between shallow geology and the observed gas flares and seabed leakages. Multibeam echosounder data and Water Column Imaging (WCI) is used to hunt the flares along the cruise, 12 flare locations are detected mostly over the hydrocarbon discoveries/fields. Well data is also used to investigate if or how some of the flares might be connected to the drilling activities. However, not all amplitude anomalies in the WCI are gas flares, thus a protocol to define gas flares in WCI is applied. Tectonic movements and uplift in the study area cause faulting and fault reactivation, which open migration pathways from reservoir levels and fluids escape towards the seabed. Additionally, erosion and removal of as much as 2km sediments reduce the overburden pressure, causing the reservoir fluids to expand and escape. Repeated glaciation events during the last ice age formed an unconformity surface (URU) where many potential shallow gas accumulations locate. Shallow accumulation/seismic anomaly along the URU is the main target of this thesis. Some of the observed gas flares are closely related to hydrocarbon wells in the study area, gas might migrate through well-induced fractures along the wellpath. The relationship between deeper gas accumulations, hydrocarbon wells, shallow gas accumulation and potential leakage of gas into the water column is not straight forward. More empirical data and investigations needs to be applied to increase the knowledge of these interrelated and complicated processes

The aim of this study is to investigate the tectonic- and evolutionary differences between major structural elements of the Barents Sea South East (BSSE) during the uppermost Triassic to lower Cretaceous. The study area comprises the following structural elements: the Bjarmeland- and Finnmark platforms, the Nordkapp- and Tiddlybanken basins, the Signalhorn-, Haapet- and Veslekari domes and the Fedynsky High. Interpretation of seismic 2D- and well-data from the exploration well 7435/12-1 have provided the stratigraphic framework on the uppermost Triassic to lower Cretaceous, represented by the Realgrunnen Subgroup (late Norian to Bajocian), the Fuglen Formation (Callovian to Oxfordian) and the Hekkingen Formation (late Oxfordian to Tithonian). Thickness variations, and seismic stratigraphy as reflection geometries and terminations were applied to identify structural events such as uplift, subsidence and periods of erosion. Insight in the tectono-stratigraphic evolution of the Barents Sea South East have been provided by variations in the thickness and termination patterns of the uppermost Triassic to lower Cretaceous units. This study suggests a late Norian to Bajocian (represented by the Realgrunnen Subgroup) elevation of the Fedynsky High, Finnmark Platform, Veslekari- and Signalhorn domes. During the same period, a relatively stable platform configuration was valid for the Bjarmeland Platform and northern section of the Finnmark Platform, and concurrent basin configuration of the Nordkapp Basin, what today is the Haapet Dome and the area northeast of the dome structure. The structural trends valid for the late Norian to Bajocian continued into the Callovian to Oxfordian (represented by the Fuglen Formation), excluding the Haapet Dome, Bjarmeland Platform and north part of the Finnmark Platform in which the former experienced uplift and the two latter experienced subsidence during this period. The tectono-stratigraphic evolution of the Callovian to Oxfordian persisted through the late Oxfordian to Tithonian, accompanied by a rise in relative sea-level (represented by the Hekkingen Formation), in addition to subsidence of the Tiddlybanken Basin. Late Norian to Tithonian structuring of the BSSE are suggested to be linked to the possible reactivation of deep lineaments by the final upthrusting of the Novaya Zemlya (Late Triassic – Early Jurassic) and also the tectonic events that influenced the NE Atlantic rifting (Late Jurassic – Early Cretaceous) and later opening

Seismic interpretation, water column data, and well information have enabled a thorough review of shallow amplitude anomalies and subsurface faulting, in conjunction with possible migration pathways in the Haapet Dome area. The processed water column data from the MAREANO-program was presented and evaluated in accordance with potential gas leakage from the seafloor. Water column imaging illustrates that hydroacoustic signatures, which are representative of gas bubble leakage, are probably of non-existence in the Haapet Dome area. A correlation with subsurface stratigraphy illustrates that the possible gas accumulations are situated in the Stø and Nordmela formations, and the Early Cretaceous unit. Given that no apparent evidence of gas leakage is occurring suggests that a sealing lithology is constraining the assumed gas accumulations. Several models were introduced to discuss and evaluate the possible gas accumulations according to entrapment capability and the possibility of minor gas release. The analysed water column data did not indicate observable gas leakage, where acoustic distortion made detection of potential gas bubbles difficult. The Upper Regional Unconformity (URU) with overlying glacial sediments was assumed to act as a potential trapping mechanism for underlying zones of potential shallow gas accumulations. A gas hydrate stability model was established, which showed that gas hydrates could develop in the study area, dependent on the gas composition. Consequently, local zones of potential gas hydrates could act as hydrocarbon barriers. A possible Permian source rock was suggested to have generated and expelled gas, which is probably represented by its present-day shallow accumulations. The models presented suggest that no source rocks are generating and expelling hydrocarbons at present-day in the study area. The assumed shallow gas accumulations are thereby represented by a possible older working petroleum system. A shut-down petroleum system, with no or very little influx of hydrocarbons to the study area, combined with shallow sealing lithologies, might be one reason for lack of observed gas seepage in the water column.

Carbonates represent major hydrocarbon reservoirs, but often exhibit highly heterogeneous reservoir properties. Outcrop analogues provide important insights into how parameters such as porosity, permeability and natural fractures vary. As such, outcrops can bridge the scale gap between spatially extensive but poor-resolution seismic data and 1D high-resolution well data. However, traditional geological fieldwork typically gathers insufficient data to construct robust geological models. In this study, we have specifically set out to gather key data sets that enable the construction of a geology-driven model. We illustrate this workflow using the exceptionally well-exposed carbonate-dominated outcrops of the Kapp Starostin Formation in central Spitsbergen, Arctic Norway. We fully utilize emerging technologies, notably geo-referenced digital outcrop models (DOMs), to be able to gather quantitative sedimentological-structural data from otherwise inaccessible cliffs. DOMs generated from digital photos are used directly for automatic and manual mapping of fractures. The digital data are complemented with traditional fieldwork (sedimentological logging, scanlines, structural characterization) in order to strengthen the dataset. The geo-modelling involves traditional facies and petrophysical modelling of the 12 identified facies, along with outcrop-based discrete fracture modelling. Finally, the static geo-model is upscaled, and its applications are discussed. The presented workflow uses carbonate outcrops of the Kapp Starostin Formation as input but is highly applicable for other studies where outcrops can be utilized as direct input to constrain a geological model.

The Barents Sea is a large epicontinental sea and petroliferous basin, which is fairly unexplored compared to other regions of the Norwegian Continental Shelf (NCS). The structural configuration of the SW Barents Sea is characterized by a complex mosaic of structural highs, platforms and basins, reflecting the interplay between multiple tectonic phases. Late Cenozoic glacially induced subsidence and uplift, and extensive differential erosion, may have had a major impact on the petroleum systems in the area, causing a reconfiguration of the fluid flow systems by gas expansion, oil-spill, migration and remigration of hydrocarbons into the shallower subsurface. Subsequent accumulations of shallow gas may represent significant drilling hazards, potential commercial hydrocarbon resources or be indicative of deeper prospective reservoirs, and are as such important exploration targets. Identification and analysis of fluid flow indications and their relationship to the structural development and denudation history of the Loppa High will provide a better insight to the controlling mechanisms of fluid flow systems on both a local and regional scale. Seismic interpretation, spatial visualization and analysis of 2D and 3D data from the northern margin of the Loppa High have revealed numerous fluid flow indications such as leaking faults, gas chimneys, shallow gas accumulations and buried and exposed depressions. The complex structural development of the Loppa High has led to the development of several sets of faults, which have been classified as deep-seated Permian, vertically extensive Permian-Triassic and shallow Triassic. The larger-scale structural geology of the study area encompasses narrow grabens and extensive horsts, believed to reflect Carboniferous-Permian rifting, extensional faulting related to the proto-Atlantic rift system and later rifting events associated with the opening of the Norwegian-Greenland Sea. The numerous faults identified may constitute a larger network of potential fluid conduits, connecting deeper reservoirs with shallower, suggesting a structural control on the fluid flow systems in the study area. Gas chimneys and high-amplitude anomalies occurring at several levels within the subsurface strata, and the presence of both buried and exposed seabed depressions, testifies to vertical and lateral migration from deeper source rock intervals, gas accumulations along faults and URU, and episodes of potential gas release at the seabed. Observations and results largely correspond to similar studies carried out in the SW Barents Sea region, supporting the theory that fluid flow systems in the area are at least partially structurally controlled and that the distribution of fluid flow systems may have been altered by Late Cenozoic tectonic readjustments through extensive uplift and erosion.

A meteor impact event on the Bjameland Platform in the Norwegian Barents Sea about 142 ± 2.6 million years ago formed the Mjølnir Impact Crater. The structure has diameter of 40 km impacting the Mesozoic stratigraphy, and has previously been investigated with emphasis on the dynamics of the impact, the structure formation, sedimentation and post-impact tectonics. Impact structures have proven to be petroliferous elsewhere in the world. By applying new seismic 2D- and P-cable data and integrating prior studies, this thesis focuses on how the structure of the Mjølnir Impact Crater might represent a petroleum system in the Barents Sea. The structural setting of the Mjølnir impact Crater shows several potential structural traps, including horst and graben structures within the crater, and listric rim faults at the periphery. A simplified 1D maturation model of potential source rocks in the area, indicate that the Hekkingen and Steinkobbe formations are sufficiently matured and have generated oil, while the Lower Triassic formations have generated gas. These source rocks may potentially charge the Mjølnir Impact Crater by petroleum migration vertically along deep-seated faults and laterally in the southward dipping stratigraphy, from the Nordkapp Basin area. The southern section of the Mjølnir Impact Crater is considered have the highest hydrocarbon potential, due to a thicker overburden and favorable migration pathways. Five seismic anomalies of high amplitude have been identified in the southern Mjølnir Impact Crater. These are interpreted to represent hydrocarbon accumulations, structurally trapped in horsts and by listric rim faults, and overlain by Upper Jurassic shales with sealing properties. Volumetric calculations for one of the amplitude anomalies suggest that 24,4 MMSm3 of oil may be accumulated at the southern boundary of the crater. In conclusion, presence of source rocks, migration pathways, reservoir and traps supported by observations of seismic amplitude anomalies suggests that the Mjølnir Impact Crater represents a potential hydrocarbon system.

Accepted manuscript version, licensed CC BY-NC-ND 4.0. Published version available at https://doi.org/10.1016/j.marenvres.2018.09.004. Due to retreating sea ice and predictions of undiscovered oil and gas resources, increased activity in Arctic shelf sea areas associated with shipping and oil and gas exploration is expected. Such activities may accidentally lead to oil spills in partly ice-covered ocean areas, which raises issues related to oil spill response. Net Environmental Benefit Analysis (NEBA) is the process that the response community uses to identify which combination of response strategies minimises the impact to environment and people. The vulnerability of Valued Ecosystem Components (VEC's) to oil pollution depends on their sensitivity to oil and the likelihood that they will be exposed to oil. As such, NEBA requires a good ecological knowledge base on biodiversity, species' distributions in time and space, and timing of ecological events. Biological resources found at interfaces (e.g., air/water, ice/water or water/coastline) are in general vulnerable because that is where oil can accumulate. Here, we summarize recent information about the seasonal, physical and ecological processes in Arctic waters and evaluate the importance these processes when considering in oil spill response decision making through NEBA. In spring-time, many boreal species conduct a lateral migration northwards in response to sea ice retraction and increased production associated with the spring bloom. However, many Arctic species, including fish, seabirds and marine mammals, are present in upper water layers in the Arctic throughout the year, and recent research has demonstrated that bioactivity during the Arctic winter is higher than previously assumed. Information on the seasonal presence/absence of less resilient VEC's such as marine mammals and sea birds in combination with the presence/absence of sea ice seems to be especially crucial to consider in a NEBA. In addition, quantification of the potential impact of different, realistic spill sizes on the energy cascade following the spring bloom at the ice-edge would provide important information for assessing ecosystem effects.

This study has investigated salt movements in the Nordkapp Basin, on the Loppa High (Svalis Dome) and on the Bjarmeland Platform (Samson- and Norvarg domes). The aim is to discuss how differences in salt growth potentially relates to the structural evolution of - and differences between - these three provinces. Evaluation of seismic 2D- and 3D data together with well correlation, allowed a regional stratigraphic framework to be established for the Permian-Quaternary succession. Four stratigraphic units were defined: Lower Triassic, Lower to Middle Triassic, Middle Triassic-Jurassic and Cretaceous-recent. Thickness variations and reflection configurations within these units, together with salt morphology, documented the timing of salt growth. In the Nordkapp Basin, several phases of salt growth occurred throughout the Triassic, a period usually referred to as tectonically quiet in the southwestern Barents Sea. Extensional forces locally lead to subsidence and faulting/steepening of the basin margins. A regional extensional event lead to renewed salt growth during the Cretaceous, before Cenozoic regional compression squeezed the diapirs, resulting in a final growth phase. At the Svalis Dome, a salt pillow grew during the Early to Middle Triassic-Jurassic. Later uplift and erosion of the dome resulted in renewed growth and diapirism. Little or no salt movements are observed on the Samson- and Norvarg domes during the Mesozoic, but Cenozoic compression appears to have mobilized the salt. The main differences in salt growth between the three provinces seem to relate to the different structural settings; in the Nordkapp Basin, diapirs grew already in the Triassic possibly due to extensional forces in and adjacent to the basin. On the Svalis Dome, the salt growth seems to relate to a large degree of uplift of the Loppa High. At the Bjarmeland Platform, a late initial growth stage reflects a tectonically stable environment until Cenozoic regional compression mobilized the salt.

A thorough review of the Oligocene-Miocene stratigraphic evolution and depositional environments in the Norwegian part of the southern North Sea is presented and considered alongside observations of petroleum system indicators, from seismic-, core- and well-data. The reconstructed paleo-environments show a trend of fluctuating eustatic sea-levels, controlled by basin subsidence and uplift of the Fennoscandian Platform in the north, coupled with growth and melt of the Antarctic Ice Sheet. Stages of rising sea-level are reflected by low-angle, sigmoidal clinoforms with ascending shelf-break trajectories deposited simultaneously to rapid basin subsidence. Periods of a relative fall in sea-level are characterized by complex-oblique clinoform stacking patterns, with a distal displacement of the shelf and descending shelf-break trajectories. Falling stage system tracts are dominated by the evolution and progradation of complex channel systems and erosion of the exposed shelf. Lowstand system tracts are recognized where coarser, sand-rich material was deposited towards the distal basin margins. The results provide new insight on the subsurface drainage system, as well as an evaluation of a potential Oligocene reservoir rock, the Vade Formation, which in general showed good reservoir properties. This work proposes an updated depositional model for the sandstone, with a newly defined lateral reach, extending beyond the previously established boundaries of this formation. The suggested model describing the petroleum system favours lateral drainage with migration focused sub-horizontally through the permeable Vade Formation which is capped by transgressive, sealing lithologies. Here a persuasive correlation to a Jurassic source rock, the Mandal Formation, is outlined, providing a tentative basis on which to endorse a thermogenic origin of the observed hydrocarbon indications with long distance lateral migration enabling accumulations to form far from the petroleum kitchen area. A differential entrapment model alongside potential leakage and well-information, provides an explanation for the dry wells adjacent to possible hydrocarbon accumulations in the region. The evaluation of the petroleum system sheds new light on the potential for several hydrocarbon filled structures in the subsurface of the Norwegian southern North Sea.

On the Norwegian Continental Shelf, the western Barents Sea shelf is generally ice-free and proven by recent discoveries as a frontier area for hydrocarbon exploration. During the Cenozoic, most of the areas of the Barents Sea were subjected to significant uplift and erosion, processes that have had important consequences on the petroleum systems. This thesis aimed to investigate the estimation of the net apparent erosion in the southwestern Barents Sea and consequently to determine the regional variation and magnitude of the net erosion by studying the compaction of selected stratigraphic layers. An integrated approach based on seismic interpretation of multi-client seismic data, shale and sandstone compaction combined with a rock physics application was used in order to estimate the amount of net apparent erosion in the study area. The findings will further serve as input to the overall understanding of the reservoir characteristics, the maturity of the source rocks, timing of expulsion and the retention of hydrocarbons in the traps. The PhD thesis work was carried out at the Department of Geosciences, UiT-The Arctic University of Norway, North Energy ASA in Tromsø and Oslo and First Geo AS in Oslo.

Source at https://doi.org/10.5194/se-9-341-2018. The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle–Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, (i) the Måsøy Fault Complex, (ii) the Rolvsøya fault, and (iii) the Troms–Finnmark Fault Complex. We discuss the formation of the Måsøy Fault Complex as a possible extensional splay of an overall NE–SW-trending, NW-dipping, basement-seated Caledonian shear zone, the Sørøya–Ingøya shear zone, which was partly inverted during the collapse of the Caledonides and accommodated top–NW normal displacement in Middle to Late Devonian–Carboniferous times. The Troms–Finnmark Fault Complex displays a zigzag-shaped pattern of NNE–SSW- and ENE–WSW-trending extensional faults before it terminates to the north as a WNW–ESE-trending, NE-dipping normal fault that separates the southwesternmost Nordkapp basin in the northeast from the western Finnmark Platform and the Gjesvær Low in the southwest. The WNW–ESE-trending, margin-oblique segment of the Troms–Finnmark Fault Complex is considered to represent the offshore prolongation of a major Neoproterozoic fault complex, the Trollfjorden–Komagelva Fault Zone, which is made of WNW–ESE-trending, subvertical faults that crop out on the island of Magerøya in NW Finnmark. Our results suggest that the Trollfjorden–Komagelva Fault Zone dies out to the northwest before reaching the western Finnmark Platform. We propose an alternative model for the origin of the WNW–ESE-trending segment of the Troms–Finnmark Fault Complex as a possible hard-linked, accommodation cross fault that developed along the Sørøy–Ingøya shear zone. This brittle fault decoupled the western Finnmark Platform from the southwesternmost Nordkapp basin and merged with the Måsøy Fault Complex in Carboniferous times. Seismic data over the Gjesvær Low and southwesternmost Nordkapp basin show that the low-gravity anomaly observed in these areas may result from the presence of Middle to Upper Devonian sedimentary units resembling those in Middle Devonian, spoon-shaped, late- to post-orogenic collapse basins in western and mid-Norway. We propose a model for the formation of the southwesternmost Nordkapp basin and its counterpart Devonian basin in the Gjesvær Low by exhumation of narrow, ENE–WSW- to NE–SW-trending basement ridges along a bowed portion of the Sørøya-Ingøya shear zone in the Middle to Late Devonian–early Carboniferous. Exhumation may have involved part of a large-scale metamorphic core complex that potentially included the Lofoten Ridge, the West Troms Basement Complex and the Norsel High. Finally, we argue that the Sørøya–Ingøya shear zone truncated and decapitated the Trollfjorden–Komagelva Fault Zone during the Caledonian Orogeny and that the western continuation of the Trollfjorden–Komagelva Fault Zone was mostly eroded and potentially partly preserved in basement highs in the SW Barents Sea.

The Late Paleozoic sedimentary environments of the Ottar basin in the SW Barents Sea was studied using five 3D seismic surveys. By the use of seismic stratigraphic analysis and correlation to wells located in close proximity to the study area, the Paleozoic succession has been subdivided into 4 main units: Billefjorden Group (Late Devonian – Mid Carboniferous), Gipsdalen Group (Mid Carboniferous – Early Permian), Bjarmeland Group (Early Permian), Tempelfjorden Group (Mid- to Late Permian) and one from the Triassic: the Havert Formation (Early Triassic). All five groups have been described and discussed with emphasis on their appearance and internal seismic facies with the purpose of recreating the sedimentary processes and the paleoenvironment at time of their deposition.

This thesis focuses on the Barents Sea South East (BSSE), and the overall goal has been to investigate the regional upper Paleozoic development in the SE part of the Barents Sea. After more than four decades of negotiation between Norway and Russia, a delineation agreement came in effect in 2011. Today, the area known as BSSE is opened up for petroleum operations. As part of the opening of the BSSE, high quality 2D seismic data of the area were acquired by NPD. These 2D seismic data have been used in this thesis together with seismic stratigraphic analysis and correlation to wells in order to describe and discuss the late Carboniferous and Permian sequence. Three seismic units equivalent to the Gipsdalen, Bjarmeland and Tempelfjorden groups have been described with focus on internal horizon configuration and geometry, which forms the basis for interpreting the dominating depositional system for the different seismic units. This study finds that an overall marine setting has dominated during the upper Paleozoic interval in the BSSE. Carbonate deposition prevailed during major periods of the time interval. Thick sequences of Gipsdalen Group evaporites are found to be present in Nordkapp and Tiddlybanken basins. Salt diapirs within the basins are observed to be up to 4000 ms (twt) thick, in some places almost reaching the sea floor. Evaporites are also present in small and more locally developed basins and on nearby areas on the Finnmark and Bjarmeland platforms. The depositional environment graded from a configuration of platforms and basins that were progressively infilled by the Gipsdalen Group to a regional carbonate platform covering the entire BSSE during the deposition of the Bjarmeland Group. The youngest studied sequence is characterized by a regional open ocean environment where the sediments of the Tempelfjorden Group were mainly deposited from suspension.

Natural fractures significantly contribute to improved reservoir quality and recovery factor, especially in carbonate reservoirs. It is important to characterize the matrix and fracture properties, as well as their interaction, in order to describe the natural fracture system and improve the understanding of its effects on a reservoir. This study integrates multi-scale outcrop data from central Spitsbergen, Svalbard, to assess the impact of fractures on the reservoir potential of the Upper Permian Kapp Starostin Formation, considered as an analogue for a fractured carbonate reservoir.A combination of traditional field methods and digital geology methods was applied to analyze and characterize natural fractures. The methods include scanline measurements (~16 m), the use of the Fieldmove Clino smartphone app, photogrammetry, virtual scanlines (~2611 m) and analysis of a total of 10 virtual models. Sedimentary logging was conducted to link the fractures to 12 distinct sedimentary facies and consider their rheological effects. The 245 m long composite log indicates that the section mainly consists of light and dark spiculitic cherts with smaller units of limestones, black shales and glauconitic sandstones. Matrix porosity was derived from thin section analyses. These indicate porosities up to 30 % in the glauconitic sandstones and light spiculities, whereas the dark spiculites and limestones show 0-5 %. A total of 7 fracture sets (F1-F7) have been identified within the different facies. Most fractures are high-angled (>60°) and striking NW-SE to NNE-SSW and NE-SW to E-W, as a result of several tectonic events. These events include; (i) Early Cretaceous extension and tectonic movements along the Billefjorden Fault Zone (ii) transpressional tectonics in the Paleogene, (iii) rotation of the horizontal compression from NE-SW to ENE-WSW later in Paleogene, and (iv) Cenozoic uplift and unloading. Fracture characterization suggests that mechanical properties and lithology mainly control the fracture density. Fracture geometry and distribution are controlled by sedimentology and diagenesis. Based on the results, a conceptual fracture model has been constructed to explain the fracture development within the Kapp Starostin Formation in central Spitsbergen. Observations in this study suggest that most fractures are open or partly filled and can therefore act as conduits for fluid flow. The fractures are interpreted to be of tectonic origin, but the strata are also highly affected by diagenetic fractures and veins that originated during early burial and deposition. All data obtained in field were used as input for discrete fracture network (DFN) modelling. The generated models provide constraints on how fracture properties, such as fracture density, length and aperture, influence fracture porosity and connectivity. DFN modelling of fracture porosity suggests that the fracture porosity is highly sensitive to changes in fracture aperture and density, whereas the fracture length shows no significant impact. Fracture connectivity is dependent on changes in fracture density and did not show any effect with changing fracture aperture. Parts of the Kapp Starostin Formation are interpreted as a type I or II reservoir where porosity and permeability are fully or partly provided by the fracture network. I conclude that the upper part of the Kapp Starostin Formation could represent a suitable reservoir and that the exploitation of outcrop data provides an improved understanding of the heterogeneous fracture characteristics in a subsurface reservoir

Detailed facies analysis of the Early Cretaceous Helvetiafjellet Formation (Barremian-Aptian) indicates deposition during a long-term transgression. The formation has received a lot of attention in previous published papers, particularly the lowermost Festningen Member has been detailed in numerous papers. However, the uppermost Glitrefjellet Member is typically poorly exposed in outcrops, and consequently difficult to study. There are therefore few available studies that have investigated the Glitrefjellet Member in great detail. This study investigates stratigraphic cores (DH-1 and DH-1A) stored in Longyearbyen, aiming at describing sedimentary facies at a detail not achievable in outcrop. The detailed facies analysis presented in this thesis consequently contributes to the general understanding of the depositional evolution of the Helvetiafjellet Formation in general, and the Glitrefjellet Member in particular. Fourteen facies grouped into nine facies association have been defined. The underlying Rurikfjellet Formation consists of prodelta deposits (FA-1) and is overlain by the Helvetiafjellet Formation. The Festningen Member consists of fluvial braidplain deposits (FA-2). The overlying Glitrefjellet Member encompass a wide range of facies associations. The lowermost part include floodplain deposits (FA-3), crevasse splay deposits (FA-4), fluvial distributary channel deposits (FA-5). The uppermost part of the Glitrefjellet Member includes delta plain deposits (FA-6), delta front deposits (FA-7) and wave-reworked delta deposits (FA-8). The overlying Carolinefjellet Formation consists of offshore transition deposits (FA-9).The results of the facies analysis are compared and correlated to published sections across Svalbard, which has observed an overall thickening towards the south. However, an overall thickening towards the northwest was observed in this thesis. The significant variations in thickness are possibly related to basin subsidence or major fault zones. The depositional model is further compared to some modern analogues to the (Mahakam delta and Pamlico Sound), which is considered to be a close planform. The modern analogues contributes with information with regards to the depositional process and paleogeographic evolution and reconstruction of the Helvetiafjellet Formation shoreline. Of particular interest is the lateral relationship between barrier deposits in Kvalvågen in the east, tidally-influenced estuarine deposits to the west and a transgressive lag documented in the uppermost part of the Glitrefjellet Member to the north in the Adventdalen area. This suggests a large backstepping barrier bar complex.

This thesis is focused on studying the development of the Nordkapp Basin during the Cretaceous Period. The basin is fault-controlled and is strongly influenced by salt tectonics. The basin is divided into two parts, which differs both in the average width and direction of their elongation. Moreover, the salt structures in the northeast and southwest parts of the basin also follow the trends in width and direction. During the Early Cretaceous, the thick sequences of terrestrial sediments were deposited in the basin. Fault development and salt activity remained inactive during the Cretaceous Period, which opened the window for shelf progradation along the basin from northeast to southwest. Progradation also followed the overall regional trend, and the regional evolution of the Barents Sea directly influenced the basin as tectonic events triggered fault development and salt movements. Moreover, this also led to changes in sediment supply. The numerous 2D seismic surveys of the Southwest Barents Sea are studied in this thesis. Four reflectors are interpreted and three 3D surfaces are made. Correlation of seismic and well data helped to understand the time of deposition of the interpreted surfaces. The time-thickness maps are also made and studied in the thesis. Analysis of all the 3D surfaces helped to understand and discuss the depositional environment in the Nordkapp Basin during the Cretaceous Period. The timing of the second phase of the salt activity is also discussed.

The papers 1, 2 and 3 are not available in Munin.Paper 1: Lasabuda, A., Laberg, J. S., Knutsen, S.-M., Høgseth, G. Early to middle Cenozoic paleoenvironment and sediment yield of the southwestern Barents Sea continental margin: Insights from a regional mass-balance approach. (Manuscript). Accepted manuscript version available in Marine and Petroleum Geology, June 2018 Paper 2: Lasabuda, A., Laberg, J. S., Knutsen, S.-M, Safronova, P. A. Cenozoic tectonostratigraphy and pre-glacial erosion: A mass-balance study of the northwestern Barents Sea margin, Norwegian Arctic. (Manuscript). Accepted manuscript version available in Journal of Geodynamics, Special Arctic Issue 2018. Paper 3: Lasabuda, A., Geissler, W. H., Laberg, J. S., Knutsen, S.-M, Rydningen, T. A., Berglar, K. Late Cenozoic glacial sediment input to the Arctic Ocean – quantifying the contribution from the Barents Sea. (Manuscript). Final version with altered title, published in Geochemistry, Geophysics, Geosystems, 19(12), 4876-4903, is available at https://doi.org/10.1029/2018GC007882 The Barents Sea shelf has been experienced extensive uplift and erosion in the Cenozoic. However, the pre-glacial erosion has been so far less constrained in comparison to the glacial erosion. This paper aims to better understand the early–middle Cenozoic erosion in the western Barents Sea and the late Cenozoic erosion in the northern Barents Sea by using the mass-balance approach. The study utilizes seismic and well data to map the Cenozoic sediments and to estimate their volumes. The paleoenvironmental reconstruction is used to delineate the size of the likely source areas. From this, the average erosion and erosion rates are estimated. It is important to quantify the erosion as an effort to lower the risk in petroleum exploration in the Barents Sea. This study is also essential to understand the sedimentation pattern and their relation to the tectonic development. The paper suggests an N-S trending of uplift and erosion in the early–middle Cenozoic and E-W trending of uplift and erosion in the late Cenozoic. For the first time, the glacial erosion is estimated in the northeastern Svalbard/northern Barents Sea continental margin, which reflects the sediment input to the Arctic Ocean. The average erosion rates show one order of magnitude lower than the glacial erosion rates. The estimated numbers from this thesis are compared to the other high-latitude margins and in agreement with present-day systems.

Denne oppgaven har som hovedfokus å belyse holdninger og geofaglig kunnskap knyttet til norsk petroleumsnæring. Oppgaven tar utgangspunkt i olje- og gassfunnene Alta/Gohta i Barentshavet. Et geofaglig litteraturstudie har blitt gjennomført for å oppnå en forståelse av funnenes geologi og særegenheter. Intervjuer med norsk petroleumsnærings hovedaktører; olje- og energidepartementet, oljedirektoratet, operatørselskaper representert ved Lundin Norway og nyhetsmedier representert ved nettavisen enerWE, har blitt gjennomført for å undersøke deres kommunikasjonsstrategier og målgrupper. En spørreundersøkelse ble opprettet med mål om å utforske elementene tillit og engasjement til norsk petroleumsnæring og kunnskapsnivået knyttet til Alta/Gohta. Spørreundersøkelsen ble spredt via sosiale medier, en gateundersøkelse i Tromsø sentrum og på e-post til deltakerne ved årets OG21-forum, og det ble innhentet totalt 337 responser på spørreundersøkelsen. Intervjuene av aktørene og resultatene av spørreundersøkelsen danner hovedgrunnlaget for analysene gjort i denne studien. Et av hovedfunnene er at tillit til norsk petroleumsnæring og det generelle geofaglige kunnskapsnivå er sterkt knyttet til om man har en personlig tilknytning til næringen eller ikke, uavhengig av alder. En del av oppgavens konklusjon er knyttet til forbedringspotensialet aktørene har med hensyn til formidling, for eksempel ved mer målrettet kommunikasjon aktivt rettet mot de grupper som ikke er involvert i bransjen.

Although the Cretaceous period is known to have been dominated by greenhouse conditions, the Early Cretaceous climatic conditions in Svalbard have been under some debate. Both indicators of warm climate such as coal seams, Ornithopod tracks and warm-water dinoflagellates, and indicators of cold climate such as arctic belemnites, glendonites and ice rafted debris have been reported. This study characterises two palaeosols (Palaeosol 1 and 2) developed within the Lower Cretaceous Glitrefjellet Member of the Helvetiafjellet Formation, and investigates their validity as palaeo-climatic proxies. This analysis is based on observed features through the logging of two cores (DH-1 and DH-1A), petrographic analysis of thin sections and XRD-analysis. The petrographic analysis revealed a high percentage of quartz within both palaeosols. The combination of high quartz content and the observation of kaolinite through XRD-analysis suggests highly leached conditions. The formation of kaolinite is favoured by subhumid to perhumid climates. Both palaeosols were interpreted to be composed of two main horizons. An upper horizon A, recognized by the accumulation of organic content and a mineral fraction, and a lower horizon C, which was recognized by a pale colour, high quartz content and relict primary structures, indicating modest alteration due to soil forming processes. As a result, the two palaeosols were characterised as enitsols. Such palaeosols are regarded as immature and are thus not indicative of specific climatic conditions. The immaturity of the palaeosols was interpreted to be a consequence of several factors, where (1) high quartz content, (2) palaeosol development within crevasse splay and floodplain deposits and (3) unfavourable clastic sedimentary environment where time for plant growth and accumulation was limited were regarded as the main contributing factors. During thin section analysis, iron ooids were observed within the transgressive lag that marks the top of the Helvetiafjellet Formation. Their formation was interpreted to be a result of sediment starvation on a shallow-marine shelf that formed due to transgression and flooding of the proximal coastal plain of the Helvetiafjellet Formation. Such deposits are indicative of warm climates. Therefore, although palaeosols 1 and 2 could not be classified with regards to specific climatic conditions, other observations such as high degree of leaching, kaolinite content and iron ooids supports warm and humid climatic conditions.

Vertical and horizontal transport mechanisms for marine oil spills are investigated using numerical model simulations. To realistically resolve the 3-D development of a spill on the ocean surface and in the water column, recently published parameterizations for the vertical mixing of oil spills are implemented in the open-source trajectory framework OpenDrift (https://doi.org/10.5281/zenodo.1300358, last access: 7 April 2018). The parameterizations include the wave entrainment of oil, two alternative formulations for the droplet size spectra, and turbulent mixing. The performance of the integrated oil spill model is evaluated by comparing model simulations with airborne observations of an oil slick. The results show that an accurate description of a chain of physical processes, in particular vertical mixing and oil weathering, is needed to represent the horizontal spreading of the oil spill. Using ensembles of simulations of hypothetic oil spills, the general drift behavior of an oil spill during the first 10 days after initial spillage is evaluated in relation to how vertical processes control the horizontal transport. Transport of oil between the surface slick and the water column is identified as a crucial component affecting the horizontal transport of oil spills. The vertical processes are shown to control differences in the drift of various types of oil and in various weather conditions. This work has been funded by the Research Council of Norway through grants 244626 (RETROSPECT) and 237906 (CIRFA) and in part by a grant from The Gulf of Mexico Research Initiative (“Influence of river-induced fronts on hydrocarbon transport”, GOMA 23160700). This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The UAVSAR data are courtesy of NASA/JPL-Caltech and are available through http://uavsar.jpl.nasa.gov (last access: 19 December 2018) or the Alaska Satellite Facility (http://www.asf.alaska.edu, last access: 19 December 2018). We would also like to acknowledge the very constructive feedback from two reviewers that helped to improve this paper.

This thesis combines a geological model with a mathematical model to describe the vertical propagation of a gas plume through layers with different physical properties. The geological model is based on geophysical data from the Sørvestsnaget Basin and the mathematical model is derived based on the classical Buckley-Leverett theory for two-phase flow. The model estimates the velocity of a vertical propagating plume based fluid and rock properties. Two different cases are displayed using the model. The first case evaluates how the plume propagates in a homogenous layer and the second case looks at how the plume behaves when crossing a horizontal interface between two different lithologies. For the first case, the model predicts that the plume evolution consists of three stages. The different stages can be characterised by a different amount of shock and rarefaction waves propagating with different velocities. The model also shows that changing the fluid and rock properties does not change the evolution of the plume. However, the time taken for it to reach the different stages changes significantly. For the second case the model predicts that gas accumulation will occur beneath a boundary if the permeability and porosity above it is not sufficient enough to support the gas flow from the layer below. This results in the formation of two shockwaves travelling in opposite directions with different velocities.

While most established plays in the Barents Sea have occurred in the Mesozoic, the Alta and Gohta discoveries prove a new carbonate play concept, with a source rock that does not stem from the Jurassic. Based on depositional environment and TOC values from the Palaeozoic interval a source rock with Top Ørn as its bottom and Top Røye as its top was interpreted. Basin modelling carried out on this potential source rock concludes that the Palaeozoic interval in the Loppa High area have a good source potential. A total of 30 different models have been carried out and three highlighted models, the P10, P50 and P90 model all shows evidence of good maturity ranges (ranging from 0.5 %Ro to 1.5 %Ro) and generation potential.

The SW Barents Sea is a large hydrocarbon-prone epicontinental Sea comprised of a complex mosaic of deep sedimentary basins and structural highs. Uplift and erosion have been affecting the area on a large scale since the Cenozoic and have had a major impact on the petroleum systems in the area, resulting in spillage of hydrocarbons. The origin of the hydrocarbons are from deep source rocks, which have leaked or migrated into the shallow subsurface, forming gas hydrates and shallow gas accumulations, often accumlated in extensional fault blocks and the flanks of basins. This makes the Loppa High, bound by major faults complexes and basins on all sides, a potential target for hydrocarbon exploration. The distribution of fluid flow systems may improve our understanding of the sedimentary basins in the area. Numerous fluid flow features (e.g. fluid leakage along faults, gas chimneys, amplitude anomalies, pockmarks), and their relationship to tectonic elements and geological history have therefore been analyzed from 3D/2D seismic data. The faults in the area are divided into deep-seated faults and shallow faults, based on their vertical extent and the strata they are confined in. The deep-seated faults were probably initiated during the Permian - Early Triassic rifting and/or the Kimmerian tectonic phase in the Middle – Late Jurassic when the Atlantic rifting propagated northwards. The shallow faults are most likely the result from tectonic readjustments related to the opening of the Norwegian-Greenland Sea, in Late Cretaceous – Paleocene. This event and multiple glacial cycles resulted in multiple episodes of reactivation. Fluid migration from deeper reservoirs is evidenced by nine large gas chimneys, representing excellent migration pathways for gas. High amplitude anomalies within the Torsk Formation most likely represent accumulations of free gas below a sealing layer of gas hydrates. The occurrence of shallow gas is also probably controlled by the Opal A to Opal CT transition zone. Free gas accumulations are also represented along the URU as the unconformity may act as an impermeable barrier. Fluid expulsion events have led to the formation of circular to sub-circular depressions (pockmarks) on the seafloor. The fluid flow features occur mainly above major deep-seated faults, suggesting that the faults and occurrence of mature source rocks control the fluid flow in the area.

The Ottar basin is not yet formally defined, but is a known structural element situated under the Bjarmeland Platform in the southwestern Barents Sea, buried beneath thick, flay-lying Mesozoic strata. This thesis focuses on delineating the informal upper Paleozoic Ottar basin. The delineation presented, is based on lateral/vertical variations in lithology and the surrounding tectonic setting of the Ottar basin. Several 2D seismic surveys were utilized and interpreted for this task, with the aid of well-ties from two wells penetrating the upper Paleozoic succession (7226/11-1 and 7124/3-1) located at the Norsel High and the Nysleppen Fault Complex, in close proximity to the Ottar basin. The study includes three seismic units encompassing four different lithostratigraphic units of the upper Paleozoic succession (Billefjorden-, Gipsdalen-, Bjarmeland- and Tempelfjorden- Groups). An enclosed delineation and a geological development model of the Ottar basin has been proposed.

Source at: http://doi.org/10.1002/2017JA024744 This paper studies thermally excited emissions in the polar ionosphere derived from European Incoherent Scatter Svalbard radar measurements from the years 2000–2015. The peak occurrence is found around magnetic noon, where the radar observations show cusp-like characteristics. The ionospheric, interplanetary magnetic field and solar wind conditions favor dayside magnetic reconnection as the dominant driving process. The thermal emissions occur 10 times more frequently on the dayside than on the nightside, with an average intensity of 1–5 kR. For typical electron densities in the polar ionosphere (2 × 1011 m−3), we find the peak occurrence rate to occur for extreme electron temperatures (>3000 K), which is consistent with assumptions in literature. However, for extreme electron densities (>5 × 1011 m−3), we can now report on a completely new population of thermal emissions that may occur at much lower electron temperatures (∼2300 K). The empirical atmospheric model (NRLMSISE-00) suggests that the latter population is associated with enhanced neutral atomic oxygen densities.

Embargo of 24 months from date of publishing on accepted manuscript version. Link to publisher's version: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8127128 Copyright notice: “© © 20xx IEEE policy https://www.ieee.org/publications/rights/third-party-servers.html We show that indications of spatial dispersion effects on mineral oil slicks are observed by space-borne multipolarization synthetic aperture radar. This is readily perceived by eye when correlating multipolarization synthetic aperture radar observables with the ship track of the dispersion vessel. We investigate real full-polarimetric (linear transmit/linear receive) as well as simulated and real hybrid-polarity (circular transmit/linear receive) synthetic aperture radar features. Specifically,wegiveathoroughdiscussionofobservablesderived from the cross-correlation of two polarization channels, and compare their counterparts in the two above mentioned polarization bases.

Three-dimensional (3-D) seismic interpretations of data from the Samson Dome show direct connection between the local geological evolution of the area and the regional tectonic and stratigraphic development of the western Barents Sea. Rifting events, halokinetic movements, uplift and glacial processes influenced the area of the Samson Dome. The Samson Dome structure, located in the south-western part of the Ottar Basin, represents a structural high on the Upper Paleozoic depocentre of the Bjarmeland Platform. Salt volumes beneath the Samson Dome are in a range of 500 to 600 〖km〗^3. Many hydrocarbon indicators such as high amplitude anomalies, bright spots, zones of chaotic reflections, phase reversal reflections have been observed in the area adjacent to the salt dome. Presence of potentially significant shallow gas accumulations in the area make the Samson Dome the largest fluid-flow feature in the eastern part of western Barents Sea covering approximately 150 〖km〗^2. Here, three fault types exist in the study area, where Type 1 faults represent crestal faults, Type 2 comprises elongated sub-parallel faults, and Type 3 includes polygonal faults surrounding the dome structure. These faults act as potential fluid leakage pathways for hydrocarbons observed in shallow strata of the Samson Dome. My Master thesis comprises: analysis of the stratigraphy of the Samson Dome and mappings of acoustic anomalies and faults in the area with the aim to propose a tectonostratigraphic and fluid-flow model for the area in connection with the overall geological evolution of the western Barents Sea.

Igneous intrusions have a strong influence on petroleum systems, groundwater aquifers, and CO2 storage reservoirs, particularly because they can act as either barriers to, or carriers for fluid flow. This depends on several syn- and post emplacement processes, including fracture development in the intrusion and the host rocks, contact metamorphism of the host rocks, and hydrothermal activity. Especially a highly fractured intrusion-host rock interface can channelize fluids along the intrusion contact. This study integrates outcrop and core data from central Spitsbergen, Arctic Norway, in order to constrain the impact of Lower Cretaceous igneous intrusions on subsurface fluid flow within a siliciclastic reservoir (i.e. the Triassic Kapp Toscana Group), targeted for CO2 storage. The applied methods include fracture analyses of intrusions and host rocks, partly using digital geology and constructed 3D virtual outcrop models, and porosity analyses of the intrusion-proximal host rocks. At several localities, fracture sets both within the dolerites and the nearby host rocks, reflect the orientation of the intrusions. Fracture frequencies in general increase towards the intrusion contacts. Porosity analyses of host rocks positioned up to 4 m away from the intrusion contact of a 2.28 m thick sill in the DH4 borehole show generally low matrix porosities (on average 0.3%), with calcite cement observed to be the most abundant secondary mineral. In addition, calcite cement is frequently observed in fractures and veins within most intrusions and along the intrusion contacts, but also in intrusion-proximal host rock fractures and in faults that cross-cut the intrusions. In relation to the 2.28 m thick sill, a decrease in the occurrence of precipitated calcite, and an increase in host rock porosity is documented to occur somewhere between 4.82 m and 17.64 m from the intrusion contacts. This is largely attributed to hydrothermal activity occurring both during and after magma cooling. Based on the results from this study, a time transgressive conceptual model for rock evolution and fracture development in and around the igneous intrusions is presented, strongly benefited from 7993 fracture orientation measurements from virtual outcrop analyses. The results suggest that the igneous intrusions in central Spitsbergen primarily act as impermeable barriers to fluid flow. However, they can also provide high-permeability pathways along the highly fractured intrusion-host rock interface. Due to the presence of exceedingly fractured chilled margin of sills, a lack of calcite cement along sill-host rock contacts, no observed chilled margins of dykes, and the observation of thick (up to 10 cm) calcite veins along the dyke contacts, fluid flow is inferred to be higher along the margins of sills than along the margins of dykes. The combination of sills, dykes and other sealing features, can therefore explain why the targeted aquifer has been previously shown to be compartmentalized into several pressure units.

A seismic source on floating ice induces flexural waves in the ice layer. An exploratory data analysis of Arctic fjord ice seismic data is performed for the purpose of identifying and studying characteristics of flexural waves and other related wave modes. Both geophone and hydrophone data are examined with the purpose of studying ice properties from ice wave behavior. Power spectral density estimates provide the frequency content of the entire signal, and studies of time-frequency plots have revealed both dispersive and non-dispersive ice related waves and their corresponding frequencies. F-k spectra are applied to study the dispersion relation for both flexural and acoustic ice waves. This provides the (variation in) wavelengths for the different waves. Velocities of the flexural waves are obtained by cross-correlating receivers at known offsets and by combining the obtained wavelengths with the period found from single receiver traces. Other observed waves include a guided direct wave in ice, a seafloor reflection and its multiples, and a refracted wave. The combination of several analysis methods makes it possible to identify several characteristics and properties of floating ice related waves, contributing to the understanding of such wave behavior. Wave characteristics of flexural and acoustic ice waves are combined to find ice properties like thickness and rigidity.

Imaging and mapping igneous intrusions such a sills and dykes has been one of the challenges in recent years. However, igneous intrusions in seismic data have properties that make them good targets for visualization, such as high amplitude and sophisticated shapes. 3D visualization methods are especially well suited for sill reflections. One of the main limitations of tying offshore seismic data to onshore observations and vice versa is a matter of scale. Igneous sills that are exposed onshore might be too thin to consistently map in seismic data, whereas features that are visible in seismic surveys offshore might be too long to be able to view onshore. Understanding the geometry of these intrusions may provide key insights regarding emplacement processes, geological history, and potential for hydrocarbon exploration. The research is based on photogrammetric research, analysis of intrusions and their host rocks, and building 3-D models to use for synthetic seismic generation. Well analysis is also required in order to estimate the properties used for these synthetic seismics. Five different geometries have been tested using different lithologies for the host rocks. Sandstone/shale, organic rich shale, clean sandstone and Paleozoic carbonates. The test cases using organic shale show a high impedance contrast, where the cases using carbonates show a very low contrast, due to the similarities of the Vp and Vs with the doleritic intrusions. The sandstone/shale and shale lithologies have more contrast than the carbonates, but less than the organic rich shale. Most shapes show up fairly well on the synthetic data, however sub-vertical geometries have low visibility regardless of the lithology. There are some seismic properties that are hard to simulate using synthetic seismic, such as seismic attenuation, variance of properties within a lithology, and the presence of other geological features. Regardless, the use of synthetic seismic data may help bridge the data integration gap between onshore and offshore data.

Two shallow boreholes, 7418/01-U-01 and 7517/12-U-01, were in 1994 drilled by IKU / SINTEF on behalf of the Norwegian Petroleum Directorate (NPD) northwest of Bjørnøya in the western Barents Sea. These were part of a program totalling nine boreholes at six different locations between Bjørnøya and Svalbard. This area is not opened for petroleum activity, and the shallow boreholes were aimed at providing new data and increased geological knowledge. The two drill sites are located were reflections are subcropping below the late Neogene and Quaternary overburden, and in two different sub-basins within the Hornsund fault complex. Borehole 7418/01-U-01 was drilled at a water depth of 181.5m. Total depth from seabed was 126.15m and 113.3m of cores were cut. Borehole 7515/12-U-01 was drilled at a water depth of 156m. Total depth from seabed was 200m and 87.8m of cores were cut. Borehole 7418/01-U-01 penetrates Late Paleocene to Early Eocene strata, while borehole 7517/12-U-01 penetrates Late Paleocene strata. The cores show a diverse set of sedimentary features, ranging from primary depositional structures to detrimental bioturbation. The cores are dated to Paleogene age and show a variety of sedimentary features such as ample bioturbation, ripples and various cross stratifications. The lithology varies from mud to several sandy intervals and thinner beds of conglomerate. The findings indicate a deep marine setting for core 7418/01-U-01 and a shallow marine setting for 7517/12-U-01. This suggests that core 7418/01-U-01 correlate to the deep marine paleoenvironment to the south, while core 7517/12-U-01 correlates to the shallow marine paleoenvironment of Svalbard.

Norsk petroleumsvirksomhet har siden 1960-tallet utviklet seg til å bli en svært viktig industri. Økonomisk sett har den blitt vår bærebjelke i konstruksjonen av Norge. For samfunnslivet har den spilt en viktig rolle i å dekke gapet mellom fattig og rik; gratis helsehjelp, trygdeordninger, arbeidssysselsetting og skaperkraft er fire overordnede forutsetninger for det norske samfunn som vi kjenner i dag. Resultatet av en slik utvinning av olje har båret fram viktige hjørnesteiner i det norske samfunn. Den norske fossile fortellingen har i mange internasjonale sammenhenger blitt fremhevet som et av få vellykkede eksempler på at en nasjon har forvaltet en stor ressurs på en måte som har kommet det kollektive felleskapet til gode. Fortellingen bærer imidlertid ikke preg på en rettlinjet utvikling, preget av en gradvis harmonisering av de skapte utfordringene. De klima- og miljøendringene som nå skjer, vil få store konsekvenser for natur, samfunn og næringsliv i Norge og globalt. Tatt dette i betraktning har regjeringen en ambisiøs klima-, miljø- og energipolitikk. Regjeringen har som mål å oppnå en langsiktig omstilling til et lavutslippssamfunn innen 2050, samtidig som de vil bevare petroleumssektoren, jobbe for økt konsekvensutredning av Barentshavet og skal vi tro sentrale aktører innen norsk olje- og gass – også fortsette med utvinningen. Argumenter som at norsk olje er «grønnere» enn andre nasjoners olje, at vi må bevare sysselsetting og forminske arbeidsledighet og at petroleumssektoren skal være med i det såkalte «grønne skiftet» er noe av det sentrale aktører forteller sin offentlighet. Gjennom dokumentanalyse forsøkes det å kartlegge spenninger og motsetninger i denne debatten, og videre i analysen, drøftes det om samfunnsstyringens muligheter og begrensinger i forholdet mellom vekst/vern.

Source at: http://doi.org/10.1002/2017GC007107 The continental margin off Prins Karls Forland, western Svalbard, is characterized by widespread natural gas seepage into the water column at and upslope of the gas hydrate stability zone. We deployed an ocean bottom seismometer integrated into the MASOX (Monitoring Arctic Seafloor-Ocean Exchange) automated seabed observatory at the pinch-out of this zone at 389 m water depth to investigate passive seismicity over a continuous 297 day period from 13 October 2010. An automated triggering algorithm was applied to detect over 220,000 short duration events (SDEs) defined as having a duration of less than 1 s. The analysis reveals two different types of SDEs, each with a distinctive characteristic seismic signature. We infer that the first type consists of vocal signals generated by moving mammals, likely finback whales. The second type corresponds to signals with a source within a few hundred meters of the seismometer, either due east or west, that vary on short (tens of days) and seasonal time scales. Based on evidence of prevalent seafloor seepage and subseafloor gas accumulations, we hypothesize that the second type of SDEs is related to subseafloor fluid migration and gas seepage. Furthermore, we postulate that the observed temporal variations in microseismicity are driven by transient fluid release and due to the dynamics of thermally forced, seasonal gas hydrate decomposition. Our analysis presents a novel technique for monitoring the duration, intensity, and periodicity of fluid migration and seepage at the seabed and can help elucidate the environmental controls on gas hydrate decomposition and release.

Source at https://doi.org/10.1190/tle35080677.1. Quantitative seismic interpretation has become an important and critical technology for improved hydrocarbon exploration and production. However, this is typically a resource-demanding process that requires information from several well logs, building a representative velocity model, and, of course, high-quality seismic data. Therefore, it is very challenging to perform in an exploration or appraisal phase with limited well control. Conventional seismic interpretation and qualitative analysis of amplitude variations with offset (AVO) are more common tools in these phases. Here, we demonstrate a method for predicting quantitative reservoir properties and facies using AVO data and a rock-physics model calibrated with well-log data. This is achieved using a probabilistic inversion method that combines stochastic inversion with Bayes' theorem. The method honors the nonuniqueness of the problem and calculates probabilities for the various solutions. To evaluate the performance of the method and the quality of the results, we compare them with similar reservoir property predictions obtained using the same method on seismic-inversion data. Even though both approaches use the same method, the input data have some fundamental differences, and some of the modeling assumptions are not the same. Considering these differences, the two approaches produce comparable predictions. This opens up the possibility to perform quantitative interpretation in earlier phases than what is common today, and it might provide the analyst with better control of the various assumptions that are introduced in the work process.

Paper II, III and IV of this thesis is not available in Munin. Paper II: Beka, T. I., Smirnov, M., Birkelund, Y., Senger, K., Bergh, S. G.: 3-D Magnetotelluric imaging of Central Svalbard, Norway. (Manuscript). Published version, with title "Analysis and 3D inversion of magnetotelluric crooked profile data from central Svalbard for geothermal application" available in Tectonophysics 2016. Paper III: Beka, T. I., Bergh, S. G., Smirnov, M., Birkelund, Y.: Magnetotelluric signatures of the complex Tertiary fold-thrust belt and extensional fault architecture beneath the Brøgger peninsula, Svalbard. (Manuscript). Paper IV: Beka, T. I., Senger, K., Autio, U. A., Smirnov, M., Birkelund, Y.: Integrated electromagnetic data investigation of a Mesozoic CO2 storage target reservoir-cap rock succession, Svalbard. (Manuscript). Published version available in Journal of Applied Geophysics 2017, 136:417–430. In this thesis a series of geophysical surveys are carried out on the geologically important and remote Svalbard using magnetotelluric imaging, to constrain better the geology particularly defining geothermal resources. Magnetotellurics (MT) relays on natural source time-varying electric and magnetic field data measured at the earth’s surface in order to derive the subsurface resistivity structure. As part of the thesis, broadband MT data are collected in central and northwestern Spitsbergen in the period range between 0.003 - 1000 s from nearly 80 stations distributed along five profiles of 6 - 42 km long. The new MT data have brought significant contributions to extend the existing crustal scale geological knowledge, which mostly inferred from surficial, seismic and gravity studies in the past. From the MT data, we derived 2D and 3D resistivity models for selected areas and enabled to image the structure of the near surface bedrock geology and crustal scale architecture. The 2D and 3D inversion results indicated reasonable agreement with previous geological data, models and well reflected tectonic histories. Within the Central Tertiary Basin a higher frequency of fractures, localized faults and thick intrusive dyke swarms are resolved in the sub-horizontal and less deformed Mesozoic plat- form cover deposits. The tectonic history of the Paleocene-Eocene fold-thrust belt structure in northwest Svalbard is well indicated in the MT data from the Brøgger peninsula as a deformed architecture. The MT data from this section imaged elegantly an interplay between repeated basement-involved fold-thrust structures and successive down-dropped strata along steeply dipping oblique-normal faults that created a horst/ridge and graben/depression systems. MT is sensitive to subsurface geothermal attributes, such as fluid and heat migration zones. In this respect, the new MT data have proposed locations that may favour technologically accessible geothermal potentials.

By using high resolution multibeam swath batymetry and 2- and 3D seismic data this thesis investigate the interactions between ice streaming, glacitectonics and fluid flow in Håkjerringdjupet. The source area for a glacitectonic hill-hole pair is located directly above spatial fluid accumulations assosiated to a fault complex. Glacitectonic deposits are found directly downstream from this area. We suggest that sub-glacial gas hydrate formation due to low temperature - high pressure conditions caused basal freeze-on and subsequent glacitectonic rafting.

This master thesis studied the 3D-seismic dataset ST0825 located in the southwest Barents Sea. Aiming to map seismic anomalies and faults above and below the Upper Regional Unconformity (URU). The survey partly covers four different structural elements: Finnmark Platform, Tromsø Finnmark Fault Complex, Hammerfest Basin and Ringvassøy Loppa Fault Complex, south to north respectively. These areas are all affected by the tectonic activity from the Caledonian orogeny to lastly the creation of the North Atlantic Ocean. Making the study area complex with different faulting orientations and activity timing. The lithostratigraphy of the survey were mapped with the help of wellbore 7119/12-1, 7119/12-4 and existing publications. The different faults are mapped and categorized into First – Third class. Also, the seismic anomalies are mapped, interpret and discussed. In the survey, there are indications of migration hydrocarbon using mainly faults as migration pathways. There were also mapped a polygonal fault system, the same as Ostanin et al., (2012) mapped in the Hammerfest Basin. There were not found any indications that there have been tectonic activity post-URU, but there were indications that there has been fluid flow activity after its deposition with pockmarks mapped on the seafloor.

The 3D seismic survey ST0827 in the outer Vøring Basin reveals a complex fluid flow system consisting of hydrothermal vents, polygonal faults and acoustic pipes. The polygonal faults are bound to the fine-grained Top Brygge Formation and ooze-dominated Kai Formation. The Kai Formation is overlain by the Naust Formation, in which glacigenic debris flow units are observed. As polygonal faults can be sensitive to movement, the rapid loading from the debris flows is assumed to have reactivated polygonal faults in the area, thus allowing fluid to flow through the faults. Fluid flow indicators such as bright spots and acoustic masking in the proximity of the faults imply that fluid flow along faults has occurred, thus making polygonal faults one of the main controlling mechanisms for fluid flow development in the area. Above the termination of faults, high amplitude anomalies are found within the interbedded debris flow deposits, implying entrapment of gas. Glacigenic deposits make up one of the accumulation mechanisms in the study area. The north-north-western part of the study area is not affected by glacigenic deposits. Pockmarks would be expected, but even with acoustic masking extending all the way to the seabed, the seismic character of the seafloor reflection inhibits pockmark-identification. In addition to focussed fluid flow features, the 3D seismic data enabled identification and mapping of a gas-hydrate related bottom-simulation reflector (BSR). The BSR marks the base of the gas hydrate stability zone (BGHSZ). The BSR has a behaviour in which it crosscuts the sedimentary strata. Enhanced reflections terminate against the polarity-reversed BSR-reflection. The formation and origin of the gas hydrate and the gas hydrate-related BSR is closely related to the fluid flow in the area. A fluid flux of thermogenic origin is believed to result from the hydrothermal vents and sill intrusions. However, biogenic methane flux from the Kai Formation is also suggested as a source. The observed BSR appears between the modelled BGHSZ for 100% methane and the BGHSZ for 99% methane including 1% ethane. This supports the theory for the origin of the hydrate-forming gases being a combination of thermogenic gases from deeper depths, and biogenic gases from the Kai Formation.

Source at https://doi.org/10.3390/en11123290. The presence of a gas hydrate reservoir and free gas layer along the South Shetland margin (offshore Antarctic Peninsula) has been well documented in recent years. In order to better characterize gas hydrate reservoirs, with a particular focus on the quantification of gas hydrate and free gas and the petrophysical properties of the subsurface, we performed travel time inversion of ocean-bottom seismometer data in order to obtain detailed P- and S-wave velocity estimates of the sediments. The P-wave velocity field is determined by the inversion of P-wave refractions and reflections, while the S-wave velocity field is obtained from converted-wave reflections received on the horizontal components of ocean-bottom seismometer data. The resulting velocity fields are used to estimate gas hydrate and free gas concentrations using a modified Biot‐Geertsma‐Smit theory. The results show that hydrate concentration ranges from 10% to 15% of total volume and free gas concentration is approximately 0.3% to 0.8% of total volume. The comparison of Poisson’s ratio with previous studies in this area indicates that the gas hydrate reservoir shows no significant regional variations.

Submitted manuscript version. Published version available: http://dx.doi.org/10.1016/j.marpetgeo.2015.07.023 The location and stability of gas hydrates in the SW Barents Sea is poorly constrained due to complex geological, geochemical, and geophysical conditions, including poor controls on regional heat flow and gas chemistry. Understanding the stability of gas hydrates in this region is important, as recent studies suggest destabilizing hydrates may lead to methane discharge into the ocean and possibly in to the atmosphere. Here, we use high-resolution 3D P-Cable seismic data, combined with 3D heat flow and fluid flow models to place new constraints on gas hydrate stability in this region. The 3D P-Cable seismic data, acquired in 2009 west of Loppa High, show cross-cutting, reverse polarity, high-amplitude reflectors interpreted as the base of gas hydrate stability. To constrain heat flow, fluid flow, and gas hydrate stability within the 3D seismic volume, we use a 3D steady-state, finite difference diffusive thermal model that incorporates regional bottom water temperature from CTD casts, expected geothermal gradients, and gas composition derived from well data. In general, modelled bottom simulating reflectors are deeper than observed BSRs. Our analysis weighs multiple factors that might explain the discrepancy between observed and modelled bottom simulating reflector depths. From this analysis, we propose that the most significant discrepancies in BSR depth are likely related to changes in regional fluid/heat flow and fluid geochemistry. The anomalously shallow bottom simulating reflectors can be explained via vertical fluid flow that might include ensuing potential effects on gas composition, pore water salinity and temperature. Our estimate suggest that a maximum vertical fluid flux of approximately 12 mm/y is necessary to explain the most significant anomalies. Our study provides new insight into regional heat flow, geochemistry, and endmember vertical fluid flux rates in the Barents Sea. Moreover, it documents that the fluid flow system is active and most likely, very dynamic.

This thesis has focused on the depositional environment during the development of the Naust Formation in order to improve our understanding of the glacial history of the mid-Norwegian continental shelf, using 3D-seismic data from the Trænabanken and Sklinnadjupet area along with regional 2D-lines. Seismic anomalies have also been investigated to increase our understanding of fluid migration affecting the Naust Formation. A seismic stratigraphy of the area has been established and correlated to earlier works in adjacent areas, resulting in 5 seismostratigraphic units, N (oldest), A, U, S and T (youngest). Eleven seismic horizons in different stratigraphic levels have been mapped for geomorphological features, identifying glacial features such as cross-shelf troughs, MSGL, flutes, hill-hole pairs and iceberg plough-marks. These features suggests a dynamic glacial history on the mid-Norwegian continental shelf over the past 2.8 Ma. Iceberg plough-marks have been identified early in Naust N time (1.5-2.8 Ma), which may indicate the presence of calving ice along the Norwegian coast. Morainal deposits along with an increase in deposition of debris flows suggest a change in depositional environment taking place during Naust N time, where glacial processes became more dominant. This may be the first indication of the ice sheet reaching the paleo-shelf edge within the study area. Cross-shelf troughs, MSGL and flutes have been located on the base of unit A, S and T as well as on the seafloor. This suggests the presence of several fast-flowing ice streams in the period from ~1.5 Ma to the last glacial maximum. The Vestfjorden paleo-ice stream appears to have reached all the way down to the Skjoldryggen area during the Elsterian glaciation. However, the buildup of Trænabanken probably resulted in a change in flow pattern during the two last glaciations, where the Vestfjorden paleo-ice stream drained throughout Trænadjupet while Sklinnadjupet was dominated by ice flowing from the east. The massive loading by the thick glacial deposits of the Naust Formation resulted in polygonal faulting of the underlying Brygge Formation in the study area. This lead to dewatering, which may be the main source of fluids in the area along with fluids migrating through deep-seated faults from deeper sources. Vertical discontinuities in the seismic data suggests vertical fluid flow within pipes or through fractures created by overpressure within the Naust Formation, while some bright spots and paleo-pockmarks indicate that as the fluids encounter permeable layers the flow was freely following the stratigraphic boundaries of the prograding wedges.

In recent years, the petroleum industry started to look for new, unconventional energy resources. Peon, a shallow gas discovery in the northern North Sea, are being assessed as a possible energy resource. However, there are challenges related to reservoir pressure, sealing mechanism, and fluid migration. In this regard, geophysical and well log analyses is figured out to get a better understanding of the depositional regime and stratigraphy in the Peon area, as well as the structure of Peon and the dipping nature of the gas-water contact. During the last 1.1 million years, the Norwegian Channel Ice Stream have fed the Norwegian Continental Shelf with enormous amounts of sediments. Peon is located at the base of a regional unconformity in the outer part of Norwegian Channel. The overburden and the reservoir reveal several prominent surfaces, distinguishing sub-horizontal bedded units. The presence of iceberg plough marks and mega-scale glacial lineations on these surfaces and several till units interbedded, testifies what great actor the ice streams had during deposition. Peon reservoir deposited likely during a glacial retreat. Orientation of reservoir, erosional truncations and structures in the top reservoir indicate a glacial advance has remobilized and cut the reservoir, forming a lensoid-shaped reservoir.

This thesis has focused its efforts to identify and map faults and their relationships to shallow gas accumulations and fluid flow features. The area of this investigation lies in the hydrocarbon-prone Hammerfest Basin in the southwestern Barents Sea, above the Base Cretaceous. Nine 3D seismic datasets were used in this study, aiming to improve the knowledge of the timing of the tectonic activity and the relations and the controlling mechanisms for fluid migration and accumulation. Based on their vertical extent two fault groups exists: deep-seated and shallow faults. Deep-seated tectonic faults are further subdivided into three groups, F1, F2 and F3, based on the formation they terminate in. F1 terminates at the URU, F2 within the Torsk Formation and F3 in Cretaceous strata. Initiation of these faults occurred in the Kimmerian tectonic phase in Middle – Late Jurassic, where the E – W and NE – SW striking F2 and F3 faults experienced a small reactivation in the Barremian and Aptian. Multiple reactivations of the N – S striking F2 faults through the Cretaceous period occurred in response to thermal subsidence of the Tromsø Basin. Tectonic readjustments related to the opening of the Norwegian-Greenland Sea reactivated F2 faults and initiated the shallow faults. Faulting of the URU suggests tectonic adjustments after the onset of the Plio-Pleistocene glaciations. Fluid migration of thermogenic gas from deeper reservoirs is evidenced by seven gas chimneys located above deep-seated faults that represents excellent migration pathways for gas from deeper levels. High amplitude anomalies within the Torsk Formation most likely represents accumulations of free gas below a sealing layer of gas hydrates. The URU occasionally acts as an impermeable barrier and amplitude anomalies located along the unconformity probably represent free gas accumulations. Pockmarks on the seabed and the URU indicate at least two major events of fluid flow release, where variations in the stability conditions of the GHSZ have allowed free gas to burst upwards and create circular to sub-circular depressions. Pockmark formation could be an ongoing process if the hydrate layer is currently decomposing.

Numerous unburied seafloor pockmarks are related to current methane-leakage at Vestnesa Ridge (~79° N), west of Svalbard. About 50 km long and 1-3 km wide, Vestnesa Ridge is a 1-2 km thick sediment drift to the north of the active Molloy transform – on the eastern spreading segment. With its crest at 1200-1300 m depth, the ridge is located on young (

The papers of this thesis are not available in Munin: 1. Vadakkepuliyambatta, S., S. Bünz, J. Mienert, and S. Chand: 'Distribution of subsurface fluid-flow systems in the SW Barents Sea', Marine and Petroleum Geology (2013), vol. 43:208-221. Available at http://dx.doi.org/10.1016/j.marpetgeo.2013.02.007 2. Vadakkepuliyambatta, S., S. Chand, and S. Bünz.: 'Can ocean warming destabilize gas hydrate accumulations in the SW Barents Sea?' (manuscript). 3. Vadakkepuliyambatta, S., M. Hornbach, S. Bünz, and B. Phrampus: 'Controls on gas hydrate system evolution in a region of active fluid flow in the SW Barents Sea' (manuscript). 4. Vadakkepuliyambatta, S., S. Planke, and S. Bünz: 'Fluid leakage pathways and shallow gas accumulation in the Peon field, northern North Sea, from high resolution P-Cable 3D seismic data' (manuscript). Denne avhandlingen omfatter studier av utbredelse og evolusjon av fluid migrasjonssystemer og gasshydrater i SV Barentshavet og nordlige Nordsjøen. Avhandlingen er basert på tolkning av seismiske og brønndata og numerisk modelling av hydratstabiliteten. Store fluid lekkasjestrukturer forekommer i SV Barentshavet og viser kobling mot de store tektoniske forkastningssytemene. Det er trolig istidene (heving og erosjon) som har forårsaket fluid lekkasje fra dype reservoarer. Flere steder fører fluid lekkasje til ansamlinger av grunn gass og gasshydrat som er forholdsvis stabil i en gass sammensettning som inneholder termogene hydrokarboner. Men gasshydrat stabiliteten varierer mye i hele SV Barentshavet. Mulige gasshydrat forekomstene over store deler av det SV Barentshavet kan være følsomt for endringer i havtemperatur grunnet den globale oppvarmingen. Dette kan da føre til oppsmelting av store mengder av gasshydrat i de øvre 100 m under havbunnen over relativt korte periode (100-200 år).

Den kvartære lagpakken er analysert med fokus på glasial geomorfologi. Dette er gjort ved bruk av tre-dimensjonale (3D) seismiske data fra Nordkappbanken, sørvestlige Barentshav. I tillegg til havbunnen er det identifisert 2 begravde flater som begge er påvirket av glasiale prosesser. Geomorfologien til den stratigrafisk grunneste av de begravde flatene viser flere store depresjoner som er opp til 65 meter dype, 2 til 6 km brede og dekker et lateralt område på til sammen rundt 60 km2. Rygger av sedimenter like nord-nordvest for depresjonene har nesten samme form og volum som disse, og sammen er depresjonene og ryggene tolket til å representere “hill-hole pairs”. På samme flate er det observert rette langstrakte furer orientert sør-sørøst / nord-nordvest, tolket til å være mega-skala glasiale lineasjoner formet av raske isstrømmer. Mega-skala glasiale lineasjoner sett i sammenheng med “hill-hole pairs” indikerer pro- eller subglasial glasitektonisk deformasjon. Alderen til den begravde flaten er rundt 17.1 til 16.6 kal ka, som tilsvarer en tid da isdekket i Barentshavet trakk seg tilbake. Perioder med stillstand i tilbaketrekningen og fremrykk av isdekket har trolig spilt en stor rolle for de glasitektoniske prosessene i studieområdet. Seismiske data indikerer forekomst av grunn gass i områdene med glasitektoniske formelementer. Denne gassen kan ha ført til dannelse av svakhetssoner og ustabile sedimenter, og har trolig medvirket til glasitektonisk erosjon. Studieområdet ligger i dag innenfor stabilitetssonen for gasshydrater med struktur II, og det er indikert at denne typen gasshydrater kan ha medvirket til de glasitektoniske prosessene. På bakgrunn av at gasshydrater med struktur II inneholder tyngre hydrokarboner, og siden det er grunn gass i studieområdet er det sett nærmere på mulige migrasjonsruter for fluider. Et tett nettverk av forkastninger, saltdiapirer og påviste hydrokarboner i den underliggende berggrunnen indikerer migrasjon av tyngre hydrokarboner fra dypere hydrokarbonreservoarer opp i de grunne avsetningene. Depresjonene er dype og opptrer også på den stratigrafisk dypeste begravde flaten (URU), slik at den underliggende sedimentære berggrunnen er erodert. Denne erosjonen observeres bare i områder der den underliggende sedimentære berggrunnen består av kritt-avsetninger, noe som tyder på at kritt-enheter kan ha vært svakhetssoner som ble erodert lettere enn omkringliggende bergartsenheter. Avslutningsvis er en mulig relasjon mellom glasitektonikken og de store formelementene Nordkappbanken bueformede rygg og Nordkappbanken sedimentære kile vurdert. Nordkappbanken bueformede rygg er tolket til å være en endemorene avsatt under isdekkets fremrykk for 16 kal ka, og den glasitektoniske deformasjonen diskuteres til å ha en sammenheng med dette fremrykket. “Hill-hole pairs” er lokalisert under denne endemorenen, og det er foreslått at de kan være et resultat av proglasial oppskyving av sedimenter. Det er også foreslått at det har vært store mengder sedimentrikt smeltevann involvert i deglasiasjonen, noe som førte til at Nordkappbanken sedimentære kile ble avsatt.

Papers 2, and 4 of this thesis are not available in Munin: 2. Rajan, A., J. Mienert, and S. Bünz: 'Acoustic evidence for a gas migration and release system in Arctic glaciated continental margins offshore NW-Svalbard', Marine and Petroleum Geology (2012), vol.32(1):36-49. Available at http://dx.doi.org/10.1016/j.marpetgeo.2011.12.008 3. Anupama Rajan, Stefan Bünz, Jürgen Mienert and. Andrew J. Smith: 'Tilted bottomsimulating reflectors (TBSRs) provide evidence for active fluid flow from deep hydrocarbon sources in the SW-Barents Sea' (manuscript) 4. Anupama Rajan, Tim A. Minshull and Jürgen Mienert: 'Heterogeneous distribution of gashydrate and free gas in glaciated sediments of the NW-Svalbard continental margin inferred from changes in compressional wave velocity' (manuscript). The thesis consists of four parts and its four main objectives are: (1) to establish a potential link between serpentinization beneath a young sedimented-ocean ridge and carbon release and gas hydrate formation directly above it, (2) to understand the coexistence of free gas and gas-hydrate and to image the geophysical evidence for a geologically controlled gas hydrate, fluid migration pathway and seabed expulsion system, (3) to image the active fluid flow migration path-networks from deep hydrocarbon sources and to assess the distribution of shallow gas accumulation, and (4) to determine in detail the seismic velocity structure of the regions close to the landward limit of hydrate stability zone. The methodology implemented to realize this aims was achieved by integrating 3D seismic imaging, 1D velocity modeling to 2D seismic imaging and bathymetric and oceanographic data mapping. This PhD thesis presents results from four articles that glean into the fluid flow and gas-hydrate systems of the NW-Svalbard and SW-Barents Sea margins. The important results found during this research are: (1) new evidence for carbon release from the deep-seated source rock through the sediments above diapirism and methane capture in the inferred areas of serpentinization at the Knipovich Ridge, (2) new geophysical evidence for gas migration and geologically controlled gas hydrate system offshore NW-Svalbard, where several existing glacigenic debris flow units, which are spatially confined and influence gas migration pathways and hence, the location of gas leakage zones at the seafloor and (3) first findings of the formation of “tilted” bottom-simulating reflector in the SW-Barents Sea. They have formed due to variations in fluid flux along regions of deep-seated fault complexes causing a change in heat flow. The data also provides new evidence for the connection of deep-hydrocarbon and shallow gas hydrate, where existing fault complexes apparently act as pathways for the upward migration of fluids.

Batymetridata og 2D og 3D seismisk data og er brukt for å kartlegge formelementer i det sørvestlige Barentshavet. Megaskala glasiale lineasjoner (MSGL) kartlagt i de glasiale trauene indikerer tidligere isstrømaktivitet i Bjørnøyrenna og Djuprenna. Dynamiske endringer i strømningsretning er påvist fra MSGL med ulike orienteringer som kutter hverandre. Ut fra kartlagte MSGL er 10 strømningssett laget. Disse indikerer at isstrømmer i Bjørnøyrenna drenerte is fra store områder i nordøst. Isstrømmene i Djuprenna drenerte fjorder som Tanafjorden og Varangerfjorden, men også områder lengre øst i Barentshavet. Totalt er tre deglasiasjonstrinn påvist: Trinn 1) 17.1-16.6 ka; trinn 2) 17-1/16.6-16 ka og; trinn 3) 16 ka. Trinn 1 representerer tilbaketrekning av isen fra en ~300 km bred grunningssonekile i ytre Bjørnøyrenna mellom 17.1 og 16.6 ka. Grunningssonekilen overlappes delvis av Nordkappbanken Sedimentkile, en avsetning som er opp mot 120 meter tykk og har et areal på ~25 000km2. Sedimentkilen ble avsatt mellom 17.1-16.6 og 16 ka og representerer trinn 2. Deretter følger trinn 3, et regionalt framrykk av isstrømmene i Bjørnøyrenna og Djuprenna der Nordkappbanken Bueformede Rygg, Nordkappbanken Østlige Sedimentkile og en grunningssonekile i det sentrale Bjørnøyrenna ble avsatt. De store avsetningene viser at det var flere omfattende endringer i isens dynamikk under deglasiasjonen av det sørvestlige Barentshavet. Mindre formelementer som randmorener, smeltevannskanaler og “hill-hole pair” viser at mindre framrykk og tilbaketrekninger av isen var vanlig under deglasiasjonen av det sørvestlige Barentshavet. Havbunnen i Bjørnøyrenna og på Nordkappbanken er sterkt preget av isfjell-pløyespor. Det store antallet pløyespor er relatert til en periode med økt kalvingsrate for ~16 ka, og antas derfor å ha sammenheng med et regionalt framrykk av is under trinn 3.