Architecture, deformation style and petrophysical properties of growth fault systems: the Late Triassic deltaic succession of southern Edgeøya (East Svalbard)

The Late Triassic outcrops on southern Edgeøya, East Svalbard, allow a multiscale study of syn‐sedimentary listric growth faults located in the prodelta region of a regional prograding system. At least three hierarchical orders of growth faults have been recognized, each showing different deformation mechanisms, styles and stratigraphic locations of the associated detachment interval. The faults, characterized by mutually influencing deformation envelopes over space‐time, generally show SW‐ to SE‐dipping directions, indicating a counter‐regional trend with respect to the inferred W‐NW directed progradation of the associated delta system. The down‐dip movement is accommodated by polyphase deformation, with the different fault architectural elements recording a time‐dependent transition from fluidal‐hydroplastic to ductile‐brittle deformation, which is also conceptually scale‐dependent, from the smaller‐ (3rd order) to the larger‐scale (1st order) end‐member faults respectively. A shift from distributed strain to strain localization towards the fault cores is observed at the meso to microscale (<1 mm), and in the variation in petrophysical parameters of the litho‐structural facies across and along the fault envelope, with bulk porosity, density, pore size and microcrack intensity varying accordingly to deformation and reworking intensity of inherited structural fabrics. The second‐ and third‐order listric fault nucleation points appear to be located above blind fault tip‐related monoclines involving cemented organic shales. Close to planar, through‐going, first‐order faults cut across this boundary, eventually connecting with other favourable lower‐hierarchy fault to create seismic‐scale fault zones similar to those imaged in the nearby offshore areas. The inferred large‐scale driving mechanisms for the first‐order faults are related to the combined effect of tectonic reactivation of deeper Palaeozoic structures in a far field stress regime due to the Uralide orogeny, and differential compaction associated with increased sand sedimentary input in a fine‐grained, water‐saturated, low‐accommodation, prodeltaic depositional environment. In synergy to this large‐scale picture, small‐scale causative factors favouring second‐ and third‐order faulting seem to be related to mechanical‐rheological instabilities related to localized shallow diagenesis and liquidization fronts.publishedVersio

West Spitsbergen fold and thrust belt: A digital educational data package for teaching structural geology

The discipline of structural geology is taking an advantage of compiling observations from multiple field sites to comprehend the bigger picture and constrain the region's geological evolution. In this study we demonstrate how integration of a range of geospatial digital data sets that relate to the Paleogene fault and thrust belt exposed in the high Arctic Archipelago of Svalbard, is used in teaching in bachelor-level courses at the University Centre in Svalbard. This event led to the formation of the West Spitsbergen Fold and Thrust Belt and its associated foreland basin, the Central Spitsbergen Basin. Our digital educational data package builds on published literature from the past four decades augmented with recently acquired high-resolution digital outcrop models, and 360° imagery. All data are available as georeferenced data containers and included in a single geodatabase, freely available for educators and geoscientists around the world to complement their research and fieldwork with course components from Svalbard.publishedVersio

Digitising Svalbard’s geology: the Festningen digital outcrop model

The renowned Festningen section in the outer part of Isfjorden, western Spitsbergen, offers a c. 7 km-long nearly continuous stratigraphic section of Lower Carboniferous to Cenozoic strata, spanning nearly 300 million years of geological history. Tectonic deformation associated with the Paleogene West-Spitsbergen-Fold-and-Thrust belt tilted the strata to near-vertical, allowing easy access to the section along the shoreline. The Festningen section is a regionally important stratigraphic reference profile, and thus a key locality for any geologist visiting Svalbard. The lithology variations, dinosaur footprints, and the many fossil groups, record more than 300 million years of continental drift, climate change, and sea level variations. In addition, the Festningen section is the only natural geoscientific monument protected by law (i.e. geotope) in Svalbard. In this contribution, we present a digital outcrop model (DOM) of the Festningen section processed from 3762 drone photographs. The resulting high-resolution model offers detail down to 7.01 mm, covers an area of 0.8 km2 and can be freely accessed via the Svalbox database. Through Svalbox, we also put the Festningen model in a regional geological context by comparing it to nearby offshore seismic, exploration boreholes penetrating the same stratigraphy and publications on the deep-time paleoclimate trends recorded at Festningen

Deep-time Arctic climate archives: high-resolution coring of Svalbard's sedimentary record – SVALCLIME, a workshop report

​​​​​​​We held the MagellanPlus workshop SVALCLIME “Deep-time Arctic climate archives: high-resolution coring of Svalbard's sedimentary record”, from 18 to 21 October​​​​​​​ 2022 in Longyearbyen, to discuss scientific drilling of the unique high-resolution climate archives of Neoproterozoic to Paleogene age present in the sedimentary record of Svalbard. Svalbard is globally unique in that it facilitates scientific coring across multiple stratigraphic intervals within a relatively small area. The polar location of Svalbard for some of the Mesozoic and the entire Cenozoic makes sites in Svalbard highly complementary to the more easily accessible mid-latitude sites, allowing for investigation of the polar amplification effect over geological time. The workshop focused on how understanding the geological history of Svalbard can improve our ability to predict future environmental changes, especially at higher latitudes. This topic is highly relevant for the ICDP 2020–2030 Science Plan Theme 4 “Environmental Change” and Theme 1 “Geodynamic Processes”. We concluded that systematic coring of selected Paleozoic, Mesozoic, and Paleogene age sediments in the Arctic should provide important new constraints on deep-time climate change events and the evolution of Earth's hydrosphere–atmosphere–biosphere system. We developed a scientific plan to address three main objectives through scientific onshore drilling on Svalbard: a. Investigate the coevolution of life and repeated icehouse–greenhouse climate transitions, likely forced by orbital variations, by coring Neoproterozoic and Paleozoic glacial and interglacial intervals in the Cryogenian (“Snowball/Slushball Earth”) and late Carboniferous to early Permian time periods. b. Assess the impact of Mesozoic Large Igneous Province emplacement on rapid climate change and mass extinctions, including the end-Permian mass extinction, the end-Triassic mass extinction, the Jenkyns Event (Toarcian Oceanic Anoxic Event), the Jurassic Volgian Carbon Isotopic Excursion and the Cretaceous Weissert Event and Oceanic Anoxic Event 1a. c. Examine the early Eocene hothouse and subsequent transition to a coolhouse world in the Oligocene by coring Paleogene sediments, including records of the Paleocene–Eocene Thermal Maximum, the Eocene Thermal Maximum 2, and the Eocene–Oligocene transition. The SVALCLIME science team created plans for a 3-year drilling programme using two platforms: (1) a lightweight coring system for holes of ∼ 100 m length (4–6 sites) and (2) a larger platform that can drill deep holes of up to ∼ 2 km (1–2 sites). In situ wireline log data and fluid samples will be collected in the holes, and core description and sampling will take place at The University Centre in Svalbard (UNIS) in Longyearbyen. The results from the proposed scientific drilling will be integrated with existing industry and scientific boreholes to establish an almost continuous succession of geological environmental data spanning the Phanerozoic. The results will significantly advance our understanding of how the interplay of internal and external Earth processes are linked with global climate change dynamics, the evolution of life, and mass extinctions

The Svalbard Carboniferous to Cenozoic Composite Tectono-Stratigraphic Element

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

Active gas seepage in western Spitsbergen fjords, Svalbard archipelago: spatial extent and geological controls

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

Development of extensional growth basins: A field based study, Svalbard, Norway

The growth style and evolution of syn-sedimentary faults influence the architecture of the basin and thus control both the geometries and distribution of sedimentary facies belts. The architecture of sedimentary basin fill reflects a combination of tectonic and climatic controls that are relatively unique for each geological setting. This statement was tested in Svalbard, Norway, where recent post-glacial topography and a lack of vegetation reveal unique outcrops that allow detailed investigation of spatio-temporal basin fill development. Field studies were conducted in two locations: in the Upper Carboniferous Billefjorden Trough outcropping in central Spitsbergen, and in Kvalpynten, Edgeøya, wherean array Upper Triassic growth faults is exposed. This body of work consists of four scientific articles. Field-based results from detailed sedimentological logging, structural measurements and geological mapping were combined with analysis of three-dimensional outcrop models (derived from LIDAR scans and photogrammetry). Published data such as lithostratigraphy from the boreholes and sedimentary logs were also integrated to form an extensive and coherent database. A ca. 25 km wide basin fill of the Billefjorden Trough records the transition from a continental to a paralic sedimentary facies that formed in response to the opening of a connection to the sea. Early syn-rift deposition occurred in a basin segmented into the hanging wall blocks of meso-scale (tens to hundred meters of displacement) growth faults, in partly isolated sub-basins. In this phase the Billefjorden Trough was a symmetrical basin. Later on, half-graben geometry developed during the rift climax, highlighted by deposition of up to 400 meters of alluvial fan deposits confined to the master fault zone. Meso-scale faults have segmented the dipslope into proximal and distal part. The tectonic impact on the basin fill was the greatest near the master fault zone and in the proximal dipslope. The imprint of eustatic sea level prevails over the 13 tectonic influence in the distal dipslope. Rift reorganization and narrowing phase redefine the basin configuration, which is less asymmetric than in the rift climax and subsides more slowly. Growth fault displacement maxima define zones on the footwall blocks, with evaporite dissolution and formation of stratiform breccias. A narrow, centrally located depocenter on the hanging wall block formed between two antithetic faults, was protected against dissolution and contains thick beds of evaporites. The world- class growth faults in Kvalpynten bound twelve ca. 250-800 m wide basins filled with prodelta to lower delta front mudstones and shales. The basin fills consist of tens of meters thick, coarsening upward units, where the sandy parts represent tidal dunes and bars detached from the delta front deposits. Faults have developed due to differential compaction of the water-saturated, underlying organic-rich mudstones and the prodelta mudstones. The sediments were deposited on the structural slope dipping against the direction of prograding delta system. The structural control is reflected in syn-kinematic, late syn-kinematic and post-kinematic accommodation that in combination with relative sea level controlled the type and stacking patterns of the architectural elements filling the basins. Combined results from the tectonically-driven development of the Billefjorden rift and differential compaction-driven Kvalpynten growth faults allow discussion of the similarities and differences that result from, among other things, the driving mechanisms of faulting, the size and the type of basin fill (i.e. siliciclastic vs. mixed but -carbonate-evaporite dominated deposits). Despite the diverse scale, the extensional systems developed in both locations display similar evolution of a half-graben geometry that is pre-dated by symmetrical graben

Seeing beyond the outcrop: Integration of ground-penetrating radar with digital outcrop models of a paleokarst system

Paleokarst breccias are a common feature of sedimentary rift basins. The Billefjorden Trough in the High Arctic archipelago of Svalbard is an example of such a rift. Here the Carboniferous stratigraphy exhibits intervals of paleokarst breccias formed by gypsum dissolution. In this study we integrate digital outcrop models (DOMs) with a 2D ground penetrating radar (GPR) survey to extrapolate external irregular paleokarst geometries beyond the 2D outcrops. DOMs are obtained through combining a series of overlapping photographs with structure-from-motion photogrammetry, to create mm- to dm-resolution georeferenced DOMs. GPR is typically used for surveying the shallow subsurface and relies on detecting the contrasts in electro-magnetic permittivity. We defined three geophysical facies based on their appearance in GPR. By integrating subsurface geophysical data with DOMs we were able to correlate reflection patterns in GPR with outcrop features. The chaotic nature of paleokarst breccias is seen both in outcrop and GPR. Key horizons in outcrop and the GPR profiles allow tying together observations between these methods. Furthermore, we show that this technique expands the two-dimensional outcrop surface into a three-dimensional domain, thus complementing, strengthening and extending outcrop interpretations

Mesozoic-Cenozoic regional stress field evolution in Svalbard

Cooling fracture orientations in diabase sills associated with the Cretaceous High Arctic Large Igneous Province and syn‐sedimentary Triassic faults help constrain a model for Svalbard's (NE Barents Shelf) Mesozoic stress field evolution. Fracture data from Edgeøya and adjacent islands in SE Svalbard, from S Spitsbergen, and from literature were used to model preferred orientations and temporal relationships. Orthogonal, roughly E‐W and N‐S, joints and veins in sills from SE Svalbard are interpreted as cooling fractures influenced by the ambient stress field. Aligned preferred orientations within the Triassic host strata are associated with a regional Cretaceous jointing episode driven by sill emplacement and/or erosional unloading. The regional maximum horizontal stress (likely σ1) is inferred to have been parallel to a dominant ≈E‐W set. Spitsbergen's more complex joint patterns are associated with proximity to the Cenozoic West Spitsbergen Fold‐and‐Thrust Belt, but ≈E‐W and ≈N‐S orientations occur and are typically the earlier set. Syn‐sedimentary, ≈NW‐SE striking, Triassic normal faults in SE Svalbard aligned with the maximum horizontal stress indicate a Triassic to Cretaceous counterclockwise stress field shift, with additional counterclockwise shifting during Cenozoic dextral transpression between Svalbard and Greenland. Localized joint preferred orientations consistent with both decoupled and coupled transpression occur. Changes in the regional maximum horizontal stress and deformation regime may reflect timing of which plate margin was crucial in influencing Svalbard's plate interior stress field, starting with Triassic Uralian activity to the E, then Cretaceous Amerasian Basin development to the NW, culminating with Cenozoic dextral transpression and transtension to the SW.publishedVersio

Impact of growth faults on mixed siliciclastic-carbonate-evaporite deposits during rift climax and reorganisation—Billefjorden Trough, Svalbard, Norway

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