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The Hammerfest Basin is an E -W trending graben located between the Loppa High and the Finnmark Platform in the southern part of the Norwegian Barents Sea. Mainly siliciclastic strata of Carboniferous to Cenozoic age cover the Caledonian basement and have a total estimated thickness of 5-8 km. The basin evolved through several tectonic phases: the Carboniferous rifting, Late Jurassic rifting, the opening of the Atlantic Ocean, Oligocene reorganisation of plate movements and postglacial isostatic rebound. An E-W trending dome in the centre of the basin developed during the main extensional tectonic event in Late Jurassic. Horst structures represent the main hydrocarbon traps. Erosional channels on the flanks of the basin represent entry points for Lower Cretaceous sands. For the rest of the Cretaceous and Cenozoic intervals no significant reservoir sands are expected. The first exploration well in the Barents Sea in 1980 was located in the Hammerfest basin, and by 2019 a total of 45 wells had been drilled in the basin where 34 are classified as exploration wells. The result is 18 oil and gas discoveries, which gives a discovery rate of 53%. Two fields are now in production: the Snøhvit gas-condensate fields and the Goliat oil field. A total of 340 Msm3 (2140 Mbbl) recoverable oil equivalents have been discovered. For the middle Jurassic Play, the yet-to-find potential may be around 50 Msm3, distributed in several small structures in the basin. Following the oil discovery in the Middle Triassic interval in the Goliat structure, and because several of the previously drilled structures only penetrated the Jurassic and the uppermost Triassic section, considerable exploration potential may exist in the deeper Triassic interval in structures with the best reservoir facies. Stratigraphic traps of Cretaceous age may have a moderate petroleum potential, with excellent reservoirs encountered along the flank of the basin. Exploration potential may also exist in Upper Permian sandstones along the southern and eastern flanks of the basin. However, in large parts of the basin, the remaining potential is in the deep structures and hence is gas prone.

Presentation at the conference "Vinterkonferansen", 7. - 9.01.19, Bergen, arranged by NGF (Norsk Geologisk forening). https://www.geologi.no/konferanser/vinterkonferanser/item/947-vk19.

The circum North Atlantic-Arctic continental margin and adjacent land areas have experienced several episodes of uplift and erosion during the Cenozoic. A series of efforts quantifying this erosion for the Barents Sea shelf, where the Arctic shelf is at its widest and deepest have been done since the early 90’s using different methods. As the seismic and well database have expanded considerably, our understanding of the Cenozoic evolution of this climatic sensitive and hydrocarbon prospective area has improved. This review includes a comparison of results from different methods (e.g. the mass balance technique,shale compaction, apatite fission track, sandstone diagenesis, and seismic velocities). The Cenozoic erosion is divided into a pre-glacial and a glacial erosion. The pre-glacial erosion is related to the early Cenozoic tectonics and riftflank uplift due to the onset of rifting, shear, and compression followed by sea-floor spreading between Norway and Greenland, whereas the glacial erosion occurred during the late Cenozoic Northern Hemisphere Glaciations when grounded ice sheets repeatedly covered the Barents Sea shelf. The different methods generally show the same order of magnitude of erosion for the major source areas in the Barents Sea, i.e. northern Norway, the Loppa High, the Stappen High, Svalbard, and from the northern Barents Sea margin. Furthermore, we compare sediment load and size of drainage area from various settings and different periods. For similar size of drainage area, sediment load for glacial period is generally higher than for the pre-glacial one. Our review shows that the ratio between the Cenozoic pre-glacial and glacial sedimentation along this part of the Arctic margin is ~40%, ~50%, and ~70% for the southwestern, northwestern, and the northern Barents Sea, respectively. Thus, there is a N-S trend of increasing pre-glacial erosion of the Barents Sea shelf, whereas an W-E trend of increasing erosion is inferred for the glacial period. Future directions of research in refining the erosion estimates and better understanding the mechanisms of uplift and erosion will be addressed.

Papers 2 and 3 of this thesis are not available in Munin: 2. Rydningen, T.A., Laberg, J.S., Kolstad, V.: 'Seabed morphology and sedimentary processes on high-gradient Trough Mouth Fans offshore Troms, northern Norway' (manuscript).3. Rydningen, T.A., Laberg, J.S., Kolstad, V.: 'Late Cenozoic evolution of high-gradient Trough Mouth Fans and canyons on the glaciated continental margin offshore Troms, northern Norway – palaeoclimatic implications and sediment yield' (manuscript).

The late Cenozoic evolution of the outer continental shelf and slope on the northern part of the mid-Norwegian margin is studied using 3D seismic data. The late Cenozoic stratigraphy is subdivided into four main seismic units: unit A (oldest) to D and correlated to the established stratigraphic framework of the Naust Formation, where the oldest unit in this study correlates to the upper part of Naust unit A. The internal seismic signature of the units and the geomorphology of the unit boundaries form the basis for reconstructing the margin evolution. Palaeo-troughs and mega-scale glacial lineations (MSGLs) observed on buried shelf horizons suggest that fast-flowing ice streams drained from the Scandinavian mainland, traversed the shelf within Trænadjupet and Sklinnadjupet troughs, and reached the shelf break. Consequently, the palaeo-slope prograded westwards as downslope processes build out the margin. Based on seismic facies and geophysical attributes, the slope sediments were predominantly deposited by debris flows, but turbidity currents have also occurred. Large amount of glacial till was subglacially transported and deposited on the outer shelf and upper slope, before the sediments became unstable and redistributed downslope by gravity driven processes. The sediment distribution of the area suggests that both Trænadjupet and Sklinnadjupet troughs have been active during the glaciations; however, Sklinnadjupet Trough has been the main source of sediment during deposition of Naust A, U, S and T. Iceberg plough marks on all the buried surfaces testify to free-floating icebergs of sizes capable of eroding the outer shelf and upper slope. The Norwegian Atlantic Current was active during the margin buildout, as suggested by along slope drifting iceberg directions and the presence of the Nyk Drift on the slope.

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

Marine studies reconstructing ice sheet conditions on the Northeast Greenland shelf and adjacent fjords since the Last Glacial Maximum (LGM) are sparse. As a result, the timing and origin of the deglaciation of the ice sheet over marine areas is not well constrained. This thesis aims to improve our understanding of the LGM, deglaciation, and Holocene ice dynamics of the Greenland Ice Sheet (GrIS) near the southern outlet of the Northeast Greenland Ice Stream (NGIS), as well as reconstruct the palaeoenvironment of this region since the LGM. Here, swath bathymetry data and the multi-proxy analysis of three sediment gravity cores from southwestern Dove Bugt and Bessel Fjord were integrated. Dove Bugt is an embayment that is positioned to the east of Storstrømmen, the southern outlet of the NGIS. Bessel Fjord is a W-E oriented fjord that lies south of Storstrømmen and is connected to southern Dove Bugt via the Store Bælt sound. Bathymetric analysis of Dove Bugt revealed north-south oriented streamlined landforms which have been interpreted as the product of a fast-flowing, topographically bound branch of the NGIS that flowed southwards during the LGM. The sedimentology of a gravity core from southwestern Dove Bugt suggests that the NGIS may have retreat from the region around 11,190 cal. yr. BP, in conformity with previous onshore results. The presence of only a few, small retreat moraines implies that the deglaciation was rapid but may have had brief intervals of halting and/or readvancement. Sedimentation during the remainder of the Holocene is attributed to input from local ice caps and glaciers as well as mass wasting processes. The bathymetry of Bessel Fjord reveals several basins and sub-basin that are separated by basin thresholds. The configuration of geomorphic features suggests that glacial ice may have conformed to the topography during ice expansion and reached the outer fjord. The position of recessional moraines suggests that ice had undergone multiple halts and/or readvances and was topographically bound during deglaciation. Sediments from a gravity core collected in the inner fjord reflect a gradual transition from ice proximal to ice distal settings and an absence of glacial ice after 7,160 cal. yr. BP. A gravity core collected from a mid-fjord basin contains a transition from mud to muddy sand layers at ~4,000 yr. BP, which is believed to be the result of increased sediment input from nearby ice caps. This suggests that local ice caps in Bessel Fjord may have fluctuated with greater sensitivity to changing climatic conditions than the GrIS.

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.

The late Cenozoic evolution of the southwestern Barents Sea shelf includes periods of uplift, erosion and glaciations. This part of the stratigraphy has been studied using 2D and 3D seismic data, with emphasis on the interplay between uplift, erosion and glaciations and salt movement. The study area comprises the Svalis, Samson and Norvarg domes and the Nordkapp Basin, where halokinesis has been a major influence on the tectonostratigraphic evolution. The study includes systemization and categorization of the timing of salt activity relative to the erosion of the shelf, in the Nordkapp Basin, and on the Svalis, Samson and Norvarg domes. Very late to almost recent salt movement has occurred within some of the diapirs in the Nordkapp Basin and the Svalis Dome, evidenced by uplift of the Upper Regional Unconformity (URU) surface and the seafloor above the salt. Furthermore, the study reveals significant local variations in salt movement of the diapirs in the Nordkapp Basin, with a trend of more late salt movement towards the northeast. This is possibly attributed to a larger original salt thickness in this part of the basin compared to in the southwest. A mini-basin filled with glacigenic sediments is found adjacent to the Svalis Dome, and this is assumed to be a result of a combination of deeper glacial erosion of less resistant strata on the Loppa High, and less exposure to erosion due to the continuous salt rise and elevation of the adjacent dome. The Norvarg and Samson domes are not found to be influenced by late Cenozoic salt movement, which is attributed to factors such as original salt thickness, overburden strength and early Cenozoic erosion. Spatial variations in lithology due to salt-related doming and faulting is assumed to have influenced both the pre-glacial and later glacial erosion of the Norvarg Dome during the Cenozoic. Overall, the relationship between salt diapirism, erosion and glacial influence is found to be complex. The structural elements within the study area have experienced different pre-Cenozoic evolutions and have been exposed to varying degrees of erosion and also phases of grounded glaciers. The halokinetic history of the structural elements is also different, causing the salt structures within the study area to have different responses to the late Cenozoic uplift, erosion and glaciation of the shelf.

The late Quaternary evolution of the outer Ingøydjupet area (SW Barents Sea) is studied using a merge of conventional 3D-seismic cubes and a new generation of high-resolution 3D-seismic (TopSeis). The glacigenic sequence is subdivided into five main seismic units: unit A1 (oldest) to A5. These are separated by six glacially eroded boundaries: the Upper Regional Unconformity (URU), intra-glacial horizons (Q1-Q4) and the seafloor. A correlation to established seismic stratigraphies suggests that the units A1-A3 were deposited during middle Pleistocene and A4-A5 during late Pleistocene. The internal seismic signature of the units is described and the geomorphologies of the main surfaces are mapped. This forms the basis for a reconstruction of the ice-sheet dynamics and depositional environment during the late Quaternary evolution of the outer Ingøydjupet area. Mega-scale glacial lineations and troughs observed on the paleo-surfaces confirm that fast-flowing ice streams have occupied and eroded the outer Ingøydjupet area at least five times since the formation of the URU. The orientation of the lineations suggests that both the Ingøydjupet- and the Bjørnøyrenna Ice Streams have been active in the area during these glaciations. Buried sediment blocks, which are interpreted to have been entrained, transported and re-deposited by the paleo-ice streams indicate that the ice streams underwent phases of basal freezing. The recessional features on the URU and the seafloor suggest complex and dynamic retreats of the ice sheet following glacial maxima, where repeated halts and re-advances characterized the deglaciation. The intra-glacial horizons on the other hand show evidence of rather rapid ice sheet retreats, where mega-scale glacial lineations are preserved on the paleo-surfaces.

Low-resolution bathymetry, high-resolution seismic data (chirp) and multi-proxy analyses of three sediment gravity cores were integrated to study sedimentary processes with the purpose of reconstructing paleoenvironments in the three north Norwegian fjords Øksfjorden, Bergsfjorden and Jøkelfjorden since the last glacial. These three fjords are located on the Bergsfjorden peninsula and surround the ice cap Øksfjordjøkelen. The multi-proxy analyses of the sediment cores included measurements of the physical properties (e.g. wet-bulk density, magnetic susceptibility), X-radiography, X-ray fluorescence (XRF) core scanning, grain-size distribution analyses and visual descriptions of the sediment cores. The results suggest that four sedimentary processes occurred in the fjords: glacier-proximal sedimentation with repeated changes of physical conditions in a glacimarine environment, suspension settling in an open-marine environment with occasional ice rafting, mass wasting, as well as deltaic processes. Furthermore, the results suggest that Bergsfjorden was deglaciated prior to c. 11,090 cal. yrs. BP and that a large-scale mass-transport event took place shortly before this time. The glacier Øksfjordjøkelen has terminated in Jøkelfjorden during the last at least 8.7 ka cal. yrs. BP. An advance of Svartfjelljøkelen and Øksfjordjøkelen occurred presumably around 8.2 ka cal. yrs. BP. Glacial activity was very reduced or absent in Bergsfjorden between 7.3 and 5.0 ka cal. yrs. BP in Bergsfjorden. Relatively steady sedimentary environments are observed after 4.2 ka cal. yrs. BP in Bergsfjorden, 5.1 ka cal. yrs. BP Øksfjorden and 5.0 ka cal. yrs. BP in Jøkelfjorden.

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 sedimentary environment and seismic anomalies of the upper Brygge and Kai formations on the northern part of the Mid-Norwegian Continental Shelf is analysed from 3D seismic data and the exploration well 6604/2-1. This was done in order to give a better understanding of the paleo-climatic development in the period before the establishment of the large-scale ice sheets of the Northern Hemisphere, and to provides a better insight in the relationship to fluid and/or gas migration from different levels in the subsurface. Based on a seismic stratigraphic analysis, correlation to well logs and previous work in the area, five seismic sub-units were recognized: B1-B2 of the upper Brygge Formation (pre-mid Miocene), and K1-K3 of the Kai Formation (mid Miocene-early Pliocene). The geometry and internal seismic reflection facies, as well as the morphology of buried surfaces have been described and discussed in relation to the depositional environment and the development of the ocean circulation pattern in the Norwegian Sea. Based on the seismic analysis, a signature characteristic of contourite deposits was identified in the study area. Mounded elongated contourite drifts formed by ocean current-controlled deposition was observed in the upper Brygge Formation. After a period of tectonic uplift in the mid-Miocene, local anticlinal highs were developed, including the Helland-Hansen and Modgunn arches. These features probably played a major role in controlling the flow pattern of the ocean currents, associated with the deposition of the Kai Formation sediments. The ocean currents were entering the study area from the south, resulting in erosion in the southern part and deposition in the northern part. During the late Miocene-early Pliocene time, a change of the ocean current pattern led to erosion in the northern part, and deposition in the southeastern part of the study area. Seismic attribute analysis revealed seismic anomalies, including circular forms. These are classified into three types, based on their stratigraphic distribution and dimensions, and association with fluid and/or gas migration from deep to shallow strata. The cluster of high amplitude anomalies, including bright spots and acoustic pipes indicate fluid flow originating from deep stratigraphic levels to terminate at or near the top of the Kai Formation. Paleo-pockmarks resulted from fluid migration along major faults from a deep thermogenic source, and eventually fluid expulsion from the polygonal fault system.

This thesis has focused on the depositional environments of the Upper Triassic Snadd Formation. This formation covers the time-period Ladinian to early Norian with multiple marine regressions and transgressions, resulting in depositional environments ranging from offshore marine shelf to a coastal plain. A 3D seismic dataset and its correlating well have been studied and a refined seismic stratigraphic framework for the Snadd Formation is proposed. The area of investigation is located at the border between the Loppa High, the Bjarmeland Platform and the Hammerfest Basin. The study defines five time-stratigraphic units within the formation, bounded by regional flooding surfaces. Depositional features observed on seismic data, demonstrate distinct depositional environments within each unit. This thesis show that a marine setting dominates the lower units (Ladinian to middle Carnian), with three shorter periods of marine regressions exposing the study area to marginal marine and coastal plain processes. In the upper units (middle Carnian to early Norian), a marine regression shifts the dominating environment from marine to a coastal plain. The deposition of the Snadd Formation ends by a marine transgression, known as the early Norian flooding event.

2D seismic data have been analysed to study the Cenozoic pre-glacial sedimentary environment on the southwest Barents Sea margin and the Lofoten Basin. Based on a seismic stratigraphic analysis and correlation to previous work in the area, the pre-glacial seismic unit G0 has been subdivided into four. The four units have been described and discussed with regards to the geometry and internal seismic facies, and the sedimentary processes and depositional environment dominating during the deposition of the seismic units have been outlined.

Large seabed depressions in the Ingøydjupet Trough have previously been interpreted to be formed by sub-glacial melt-water. However, fluid migration and gas expulsion occur over large parts of the Barents Sea, which are frequently associated with seabed depressions. This thesis studies how the seabed depressions are related to sub-surface canyons on the southern part of the Loppa High, SW Barents Sea. The canyons are located stratigraphically below the seabed depressions, and high-amplitude zones at the canyon crests indicate accumulation of gas. Migration of fluids seems to take place along the canyon flanks, and the canyons and their infills have been mapped out in order to infer the distribution of shallow gas and their relation to the seabed depressions. Uplift and erosion have influenced the fluid flow system several times since the formation of the canyons. The final phase was related to glacial isostatic adjustment causing the gas to expand and build up pressure before eruption and seepage of shallow gas took place. Severe erosion further caused the seismic unit S2 to the absent in the southwestern parts of the study area. The thickness of S2 appears to affect the distribution of depressions and fluid migration, as it acts as an impermeable barrier where it is present and thus prevents fluids to reach the seabed and form depressions. The large seabed depressions above the canyons occur in areas where S2 is not present, which suggests that shallow gas is indeed a major contributor to the seafloor topography.