Provenance studies based on U-Pb dating of detrital zircons are routinely applied in basin analysis and source-to-sink studies to decipher ancient sediment pathways and the tectonic events that shaped them. The Norwegian Svalbard Archipelago, situated in the high Arctic, hosts a well-preserved upper Paleozoic sedimentary succession, deposited in the aftermath of the Caledonian Orogeny and influenced by shifting regional tectonics, which led to the formation of diverse sedimentary basins. The lower, clastic-dominated portion of the succession records a transition from extensive, pre-rift basins hosting UpperDevonian-Mississippian strata (Billefjorden Group) to narrow, fault-bounded, north-south trending rift basins hosting late MIssissippian-lowermost Permian strata (lower Gipsdalen Group). Despite its significance, the detrital zircon age signatures and sediment provenance of this succession have received limited attention. In this study, we present new detrital zircon age data from 41 samples spanning Upper Devonian to lower Permian strata across all major late Paleozoic basins in Svalbard. We analyse the zircon age signatures of individual basin-fill successions and explore the role of regional and local tectonics in driving spatial and temporal changes in sediment provenance and routing during the late Paleozoic. Particular attention is given to the connectivity of pre-rift sedimentary basins, and shifts in provenance linked to the onset of localized rifting during the late MIssissippian. Our data reveal significant provenance variability across the basins. Key findings include evidence of predominant sediment sourcing from northeastern Greenland during deposition of the Billefjorden Group (latest Devonian to Mississippian pre-rift phase). Similar zircon age signatures across the investigated basins suggest connectivity between pre-rift depocentres. The Billefjorden Trough shows signs of increasing isolation with continued rifting and subsidence. This study provides new insights into the post-Caledonian tectonosedimentary evolution of the region.

This study reconstructs the Pennsylvanian–late Permian to earliest Triassic tectono-stratigraphic evolution of the Loppa High, a long-lived structural high on the southwestern Barents Shelf. We integrate 2D and 3D seismic surveys and key wells across ~35,000 km2 to map eight regionally correlatable horizons (H1–H8) tied to the Billefjorden, Gipsdalen, Bjarmeland, Tempelfjorden and Sassendalen groups. Two-way travel-time structure maps, time–stratigraphic thickness maps and detailed fault interpretation (>150 faults) reveal three discrete Late Palaeozoic extensional fault systems and a multi-phase tectonic evolution of the area high. An ENE–WSW-striking Carboniferous system (C) parallels the Asterias Fault Complex and is linked to regionally widespread Late Mississippian–Middle Pennsylvanian rifting and development of the northern Loppa High as an early Carboniferous basement high. A Pennsylvanian–early Permian NNE–SSW system (P), antithetic to the Bjørnøyrenna Fault Complex, segments the northwestern Loppa High into the Neiden, Børselv and Kråketind sub-highs and controls distribution of Ørn Formation carbonates and Fafner evaporites. The C and P faults systems, along with Pennsylvanian regional transgression were influential controls on the depositional architecture. The youngest, late Permian–earliest Triassic N–S-striking system (T) is spatially associated with the West Selis Boundary Fault and records rift reorganization associated with tilting, uplift and erosion of the Loppa High footwall and the final drowning of the Polhem Sub-platform. The results demonstrate that the evolution of the Loppa High is tightly coupled to regional fault trends across the northwestern Barents Shelf and Spitsbergen and reflects structural inheritance relevant to the later opening of the Norwegian–Greenland Sea.

Thin sedimentary units typically constitute a large part of the volume of reservoirs targeted for hydrocarbons, CO2 storage, or groundwater but are considered to be below resolution thresholds of conventional seismic reflection data. Nonetheless, they affect seismic imaging through interference, and where lithology varies significantly over short distances, reflection characteristics may change laterally. This is especially valid for interbedded siliciclastic-carbonate systems characterised by lateral and vertical changes in lithology. We use high-resolution digital outcrop models of two interbedded siliciclastic-carbonate outcrops from Svalbard as input for seismic modelling using a 2D point-spread-function based convolution. The digital outcrop models show Carboniferous to Triassic strata, from southern Spitsbergen and Bj & oslash;rn & oslash;ya. We investigate detection thresholds (bed thickness, layer geometry, lithologic variability) and discuss their implications for resolvability on seismic data. Our base-case seismic models illustrate that units below the vertical resolution can be detected, even at high velocities (5-5.5 km/s). We present 6 scenarios to test the influence of thin (metre-scale) beds, lithological variability, faults, karstification, and imaging parameters on the seismic models. They illustrate that in mixed successions variations in reflection amplitudes, dimming and tuning effects become important for recognising thin units. Additionally, thin interfingering units can create artefacts such as apparent "faults", thus leading to misinterpretation of seismic sections in this type of depositional setting. Varying seismic imaging parameters, such as adding random noise or reducing dominant frequency decrease the detectability of thin units.

This study presents a comprehensive analysis of over 27,400 individual fractures from a digital outcrop model (DOM) of Maastrichtian-age chalk in the Rørdal Quarry, northern Jutland, Denmark. The extensive dataset, covering approximately 7,000 square meters, provides a detailed mapping of fracture networks representing a more extensive and continuous area than traditional scanlines and smaller aerial sampling methods. Analysis reveals significant spatial variations in fracture orientations and lengths, influenced by local fault systems and regional tectonics within the Sorgenfrei-Tornquist Zone (STZ). The resulting fracture network supports anisotropic fluid flow, with NE-oriented extensional fractures serving as primary pathways and NW-NNW and NNE-oriented shear fractures enhancing connectivity. Comparisons with other Danish chalk quarries, such as Sigerslev, Hillerslev, and Nye Kløv, highlight both similarities in regional trends and local variations due to factors like salt tectonics. The fractures in Rørdal exhibit a log-normal spacing distribution across the quarry, indicating a regularly spaced pattern. These findings underscore the potential of using outcrop analogues to inform subsurface models, particularly for predicting anisotropic fluid flow. However, careful consideration is required when applying outcrop data, ensuring that variations in fracture connectivity, stress regimes, and scale-dependent characteristics are accurately integrated to optimize carbon storage strategies and other subsurface applications.

This study documents a variety of deposits created by submarine landslides within the Upper Cretaceous to lowermost Paleocene Chalk Group in the Danish Central Graben and investigates the impact of remobilization on porosity. Improved visualization of the landslides in 3D seismic data compared with previous studies was facilitated by better seismic data quality for the Chalk Group, the availability of a large stack of stratigraphy-consistent horizons and the use of spectral decomposition data. The illustrated examples are chosen to reflect the spectrum of deformation styles seen in the chalk and all have a well penetrating the affected succession. They include a large collapse (375 km(2)) of an inversion ridge within the Kraka and Gorm formations, a field of large slide blocks (100-1000 m, 10-26 m) of likely lowermost Danian age embedded in the uppermost Ekofisk Formation, a debris flow system within the uppermost Tor Formation probably originating from the Ringkobing-Fyn High and fine-grained bottom current sediment waves within the lowermost Danian Ekofisk Formation. In general, porosities are higher (10-25 porosity units) in the remobilized chalk compared with time-equivalent pelagic chalk in nearby reference wells. In earlier studies this has been linked to lack of bioturbation (resulting in limited grain repacking) in the remobilized chalks owing to high sedimentation rates, resulting in a relatively open fabric during initial burial. In contrast, surrounding and covering pelagic deposits could be much more effectively bioturbated, leading to tighter grain packing during burial. The insights of this study help in the seismic characterization of mud-grade carbonate oozes and have important applications in the reservoir modelling of mud-grade carbonate reservoirs (also in light of carbon capture and storage), and in palaeo-reconstructions of pelagic seafloors since submarine landslides provide kinematic indicators.

Abstract Lower Cretaceous stratigraphy of the high palaeo-latitude Arctic-Boreal Realm is generally more poorly understood than its lower-latitude Tethyan counterpart, prohibiting regional correlations and evaluation of global climate dynamics during this important high- p CO 2 period. In this paper, a holostratigraphic scheme and lithostratigraphic revision are presented for the Valanginian–lower Barremian, siliciclastic ramp succession of the Rurikfjellet Formation in Svalbard, drawn from synthesis of the latest published sedimentological, biostratigraphic, petrophysical, sequence stratigraphic, chemostratigraphic and chronostratigraphic results, supplemented by new measured sections from five localities. The offshore mudstone-dominated Wimanfjellet Member (Valanginian–lower Barremian) is retained, whereas three new members are defined according to their distinct geographical, sedimentological and stratigraphic characteristics. The Adventpynten Member (upper(?) Valanginian–lowermost upper Hauterivian) constitutes a thick, relatively localized succession of mass-transport deposits. The Kikutodden Member (Hauterivian–lower Barremian) is discarded and replaced by the northern Bohemanneset Member and southern Fotografryggen Member, representing respectively: heterogeneous prodelta to delta front deposits; and sandy offshore transition to shoreface deposits. The Rurikfjellet Formation records Valanginian–earliest late Hauterivian shoreline progradation followed by late Hauterivian–early Barremian shoreline retreat and flooding across a low-gradient ramp, which never experienced full regression into continental deposits within the extent of the present-day outcrop belt.

The preserved Zechstein succession on the Utsira High in the NE part of the Norwegian North Sea is 25‐100 m thick and is dominated by shelf carbonates. Internal subdivision of the succession is based on the recognition of key surfaces in petrophysical logs and cores, and suggests that the carbonates mainly consist of ZS2 and ZS3 deposits and that younger ZS4 and ZS5 deposits are only locally preserved. The carbonates have undergone early, syn‐depositional dolomitization followed by later dolomite recrystallization and calcitization. Calcitization, interpreted as dedolomitization, is restricted to the upper part of the ZS3 carbonate unit and based on U/Pb dating took place during the Triassic, with a later phase of recrystallization linked to mid‐Jurassic uplift. Both dedolomitization and dolomite recrystallization relate to fresh‐water infiltration with the resetting of δO 18 values prior to the Late Jurassic drowning of the Utsira High. The reservoir quality of the carbonates is directly linked to post‐depositional meteoric diagenesis, and the best reservoir properties are recorded in intervals dominated by recrystallized dolomites in ZS2 and lower ZS3 carbonates. Dedolomitization significantly reduced porosity in the upper ZS3 carbonates.

Abstract The Late Maastrichtian Rørdal Member of the Møns Klint Formation is a remarkable lithological unit of the Danish Basin, characterized by chalk–marl cyclicity, standing out from pure Maastrichtian white chalk within the Chalk Group. A cyclostratigraphic analysis across this unit suggests a control by orbital precession and a strong amplitude modulation of the precession by the 405 kyr eccentricity cycle. Oxygen isotope data from bulk carbonate, benthic foraminifera and brachiopods indicate a prominent cooling commencing at the base of the unit, with maximum cooling aligned with a 405 kyr amplitude modulation maximum. This unit thus represents a rare example of a climatic cooling associated with a 405 kyr insolation maximum. However, geochemical and calcareous nannofossil data support lower productivity levels across the unit, in contradiction to an expected ocean fertilization accompanying enhanced continental weathering as the source of the clay material. An alternative model of deposition for this lithological unit is thus proposed via dense water cascading favoured by a sea-level low, subsequent restriction of the Chalk Sea and associated gravity currents responsible for the resuspension of fine clastic deposits from the margins of the Baltic Shield.

The Utsira High is a prominent intrabasinal basement structure in which the eroded remnants of a widespread, Late Permian, Zechstein carbonate shelf are preserved locally. The western margin of the central Utsira High is mainly characterized by weathered basement rocks with a thin Mesozoic cover. However, the recently discovered Symra Field forms an isolated sedimentary inlier basin of the area, where deeply eroded Zechstein shelf carbonates are preserved within a half-graben. The Zechstein carbonates consist of mainly ZS2 marginal marine carbonate facies and are similar to those described elsewhere from the Zechstein Basin. They are unconformably overlain by Paleogene chalks. Based on detailed facies analysis of two recently drilled cores combined with detailed petrographic and stable isotopic analysis and supplemented by age dating of selected carbonate phases using U-Pb geochronology, we show that the Zechstein carbonates have been subjected to several phases of near-surface diagenetic alterations. Volumetrically the most dominant diagenetic product comprises nonplanar dolomites interpreted to have formed by recrystallization of a precursor reflux-type dolomite phase. The recrystallized dolomites retain enhanced reservoir quality in comparison to stratigraphic equivalent ZS2 reflux-type dolomites found elsewhere on the Utsira High. Based on U-Pb-derived age constraints, the recrystallization took place during a long-lived Late Triassic exposure event of the Utsira High, and a near-surface origin for the recrystallized dolomites is proposed. The porosity enhancement occurred contemporaneously with the dolomite recrystallization process and was facies controlled. Reservoir modifications associated with the exposure led to the dissolution of CaSO4 cement, and metastable dolomite phases, in addition to the enlargement of existing pores which had created zones of weakness prone to further dissolution. Overall, the Zechstein carbonates preserved on the Utsira High illustrate the complexity of the diagenetic alterations resulting from the uplift of a carbonate shelf, and its importance for reservoir quality.

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

Abstract New carbon isotope results obtained from cores from the Fehmarn Belt (German Basin), along with hitherto unpublished detailed results obtained from brachiopods collected in the 1970s from the Hemmoor section, NW Germany, present the opportunity to revise the holostratigraphy of the Danish Basin and erect a complete chronostratigraphical scheme for the upper Campanian–Maastrichtian of the Boreal Realm based on records from the Danish and North German basins. The correlation of all studied sections is ensured by previously erected high-resolution bulk carbonate carbon isotope records. A number of issues arising from the standard Upper Cretaceous (UC) calcareous nannofossil biozonation scheme for the Boreal Realm are discussed and lead us to propose a new subzonation for the Danish Basin. Carbon isotope records allow correlation to Gubbio, Italy, the Tethyan bio-magnetostratigraphic reference, and to the astronomically calibrated ODP site 762C, Indian Ocean. Revised correlations ensure the application of magnetostratigraphy, a numeric timescale and stacking of 405 kyr cycles to the new scheme, thus erecting a detailed chronostratigraphy for the upper Campanian–Maaatrichtian of the Boreal Realm.

Bottom current activity has been responsible for the formation of a multitude of erosional and depositional features recorded in chalk. Advanced knowledge on the mobility and transport of unlithified calcareous nannofossil ooze by bottom currents is increasingly important not only for understanding the deposition of ancient chalk, but also for modelling the behaviour of modern pelagic carbonate sediments. Whereas the erosional behaviour of very pure calcareous nannofossil ooze has recently been investigated, the effect of organic matter and clay minerals on the erosional behaviour of calcareous nannofossil ooze is as yet unquantified. The results of the present study are based on laboratory flume studies utilizing chalk ooze with varying concentrations of smectite clay (1 to 30 wt.%), two types of organic matter and bed porosity. Phytoplankton (Pavlova lutheri) was used as a proxy for particulate marine organic matter, and xanthan gum as a proxy for extracellular polymeric substances. The results show a significant decrease in nannofossil ooze mobility with increasing content of clay or marine organic matter. Organic matter is found to reduce erodibility at much lower concentrations than clay minerals at porosities equivalent to those of the seafloor. At lower porosities, corresponding to some depth below the seafloor, organic matter and clay minerals are less effective in bed stabilization. This suggests that clay minerals and especially organic matter will affect the likelihood of initiation of severe erosion on the seafloor, whereas their inhibiting effect will decrease as erosion scours progressively deeper into the sediment column. The effect of extracellular polymeric substances is more complex than marine organic matter, probably due to detachment of large aggregates from the bed and resulting increase in bed roughness. The choice of organic matter in sedimentological experiments may lead to significant differences in sediment behaviour and should therefore involve careful consideration.

Antarctica and Australia were sutured together at the equator during the major pulse of animal biodiversification associated with the Cambrian radiation. However, the lack of detailed systematic chemostratigraphic and biostratigraphic sampling of lower Cambrian sedimentary successions from Antarctica has significantly impeded precise age determination and correlation with Cambrian strata on other palaeocontinents. This study is the first to present integrated, simultaneously sampled biostratigraphic and chemostratigraphic (d13C isotopes) data from the same measured stratigraphic sections through the lower Cambrian Byrd Group in the Transantarctic Mountains. Shelly fossil assemblages (brachiopods, tommotiids, molluscs, bradoriids, trilobites) from the Holyoake Range and Churchill Mountains facilitate direct correlation with the Dailyatia odyssei Zone of South Australia (Cambrian Stages 3-4), and trilobites provide strong correlation between the Starshot Formation and the Cymbric Vale Formation in western New South Wales. A new ID-TIMS radiometric date of 514.96 +/- 0.16 Ma from a tuff in the lower Cymbric Vale Formation is similar to dates from tuff beds in the Third Plain Creek Member of the Mernmerna Formation in the Flinders Ranges, providing an important absolute-age tie point between these lower Cambrian successions. Chemostratigraphic data from the upper Shackleton Limestone in the Holyoake Range capture a negative d13C excursion that can be correlated to negative values within the multipeaked MICE (cycles V-VIII in Siberia). Integrated faunal and chemostratigraphic data indicate a Cambrian Stages 3-4 age, giving robust chronostratigraphic context for the upper Shackleton Limestone-Holyoake Formation-Starshot Formation succession for the first time, permitting reconstruction of the depositional history of the lower Cambrian of Antarctica and global correlation of Byrd Group strata. (c) 2024 International Association for Gondwana Research. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

This study documents the timing and driving forces of the formation of fault-related compaction fronts in the Upper Cretaceous to lowermost Paleogene Chalk Group in the southern Danish Central Graben, based on the integration of 3D seismic, petrophysical log and clumped isotope data. The compaction fronts reflect zones in the low-permeable Chalk Group that underwent time-transgressive fault reactivation and pore fluid venting driven by movements of deeper salt and inversion movements. The fault-damage zones formed narrow permeability fairways that facilitated better drainage of compaction-driven pore fluids trapped in the matrix, eventually resulting in preferential mechanical compaction of the chalk. Salt doming during the Paleocene - Early Eocene, possibly linked to regional inversion tectonics, led to an initial phase of fault reactivation, offsetting the entire Chalk Group; pockmarks within this interval indicate release of pressurized fluids on the seafloor. Clumped isotope data from calcite-cemented veins associated with these fault-damage zones indicate precipitation from fluids that likely originated from Lower to Middle Jurassic strata at the root of these faults some 1500 m below the Chalk Group. Local thickening of the Paleocene to Lower Miocene Rogaland and Hordaland Groups matches a 20-50 m thinning of the chalk within the compaction fronts. This indicates that preferential drainage and compaction continued as the chalk became buried with clays, which became affected by polygonal-faulting causing episodic leak-offs. The results indicate that fault damage zones in low-permeability rocks may initially act as permeability fairways, but the improved drainage of formation fluids may over time cause preferential mechanical compaction and calcite precipitation. At present, the fault-related compaction fronts form lowporosity chalk bodies that may have acted as seals and/or re-directed fluid migration. The results have important implications for static and dynamic reservoir models, also in the light of Carbon Capture Storage and geothermal energy extraction and storage.

The offshore industry depends largely on usage of indirect methods, such as conventional seismics, complimented by well-scale test data and cores. These data are typically of varying quality and scales, creating an issue of non-uniqueness in the description of subsurface reservoirs used for e.g. energy and water production. The inclusion of onshore data from geological outcrops can increase the accuracy of 3D digital models used for subsurface characterization, as onshore observations can be made from micron to kilometre-scale, constraining patterns of spatial heterogeneity within geological features. We present a workflow for collecting, processing and combining geological and geophysical data surveyed at the Rørdal Chalk Quarry (Jutland, Denmark); an onshore analogue to the Maastrichtian section of the Danish North Sea. Detailed observations from these datasets can be used for identifying structural features and trends that are too small to be resolved by large-scale continuous geophysical datasets. We focus on digital outcrop models (DOMs), ground penetrating radar (GPR) and shallow seismic. The Rørdal quarry is excavated at a current rate of approximately 20–30 metres per year. The production thus continuously reveals new sections of strata. We take advantage of this unique possibility by repeatedly surveying the naturally fractured chalks using the applied methods. Strategic data collection has enabled tracing of structural elements in a three-dimensional domain. The construction of 3D volumes creates a solid foundation for a conceptual geological model as well as for static modelling of the quarry, which would not be obtainable working with individual datasets. As different geological features appear differently in the geological and geophysical data, their lateral extent and orientations can be evaluated in greater detail. The DOMs allows for structural interpretation and analysis in the digital space. We have established a statistically unique dataset containing 27,400 digital fracture interpretations on cm scale. This would not be possible to collect manually in the field. This extensive dataset offers two key strengths to alleviate typical uncertainties in outcrop studies; the dataset is large and it is taken from an area of near-continuous exposure, providing a population of observations that we believe to be both statistically significant and representative of natural variability in the system.

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

An appraisal of ancient Earth’s climate dynamics is crucial for understanding the modern climate system and predicting how this might change in the future. Major climate-shift events in the Earth’s past demonstrate the scale, duration and response of the climate system to various global and local climate stressors. More than 650 million years of deep-time paleoclimate changes are archived in the sedimentary succession of Svalbard; an archipelago located in the Norwegian High Arctic. The excellently outcropping geological successions of Svalbard date back to the Proterozoic, and record both temporal and spatial changing climatic and environmental conditions strongly linked to the northward continental drift of the archipelago from southern hemisphere in Precambrian to its present-day Polar latitudes. The oldest deposits that record major climatic events and associated environmental perturbations in Svalbard include tillites related to several Cryogenian glacial events and the overlying Ediacaran carbonates. The Lower Paleozoic succession documents episodes of marine biodiversification, including the Great Ordovician Biodiversification Event (GOBE), which is linked to cooling of previously warm tropical oceans. The arid to semi-arid climate of the Devonian promoted a terrestrial plant diversification. The Lower Carboniferous coal-bearing strata were deposited in humid and tropical climate settings prevailing in northern Pangea. The Upper Carboniferous-Lower Permian succession consists of interbedded carbonates, evaporites and red siliciclastics, including remains of paleokarst. The continued northward drift into subtropical latitudes promoted a change back to arid to semi-arid climates, occurring during the overall global icehouse conditions. During the Late Permian, marine sponges were occupying most of the ecological niches, leading to the deposition of weathering-resistant spiculites. But these ecosystems were rapidly and dramatically impacted by the End Permian Mass Extinction (EPME), which lasted well into the Early Triassic. By the Mesozoic, Svalbard was approaching mid-latitudes. The exposed in Svalbard deposits of Triassic mega-delta features evidence for a temperate or humid climate, indicated by thick coal beds that transitioned to an arid climatic environment at the end of the Triassic and Early Jurassic succession with caliche and calcareous soil profiles. The Lower Cretaceous strata (deposited at c. 66 °N) record several cold snaps despite the overall greenhouse climate characterizing the period and most notably the global crisis associated with the Aptian oceanic anoxic event 1a (OAE1a). By the Paleogene, Svalbard had reached Arctic latitudes, and as characterised by overall moderate to warm temperate climate, punctuated by warming episodes, including the Palaeocene–Eocene Thermal maximum (PETM). The Neogene cooling is missing from onshore records, but high-resolution glacial climate evidence exists offshore and from geomorphology and unconsolidated strata of Late Quaternary-Holocene age. In this contribution, we synthesize former and ongoing studies of deep-time paleoclimate in Svalbard and provide knowledge gaps to optimize the use of Svalbard as an archive for deep-time paleoclimate research. The exceptional exposures, accessibility, and completeness of the 650 million long sedimentary records makes Svalbard unique archive for deep-time paleoclimate research. In addition to Svalbard’s excellent outcrops, fully cored research and coal exploration boreholes provide an excellent foundation for further research with minimal environmental consequences.

Interference and inherent resolution limitations are well-recognized problems in reflection seismic data and have over time led to misinterpretations. Acquisition of seismic data containing a broad range of frequencies, including high frequencies, does not solve this problem but merely moves the problem to a finer scale. Forward seismic modeling of known geological scenarios is a valuable tool for studying anticipated seismic responses of successions with a given set of geological and/or rock physical characteristics and for predicting interpretational challenges. The objective of this paper is to demonstrate that interbedded strata with contrasting physical properties and variable thickness can result in interference effects resembling faults and fractures. We conduct finite-difference-based seismic forward modeling on a conceptual geological model derived from outcropping chalk sections in SE Denmark, and present possible pitfalls that may hamper interpretation of seismic data acquired from strata with similar characteristics. The result has significance for characterization of e.g., geothermal sites, potential CO2 storage targets, groundwater reservoirs and hydrocarbon exploration sites, in which proper imaging of faults and fractures from seismic is an essential task.

This study proposes a unique workflow to unravel complex burial diagenetic histories of overpressured basins based on the integration of seismic and well log data, biostratigraphy, petrography, clumped isotope analyses and basin modelling. This approach is demonstrated with an example from the Chalk Group in the Danish Central Graben, where a seismic‐scale palaeo‐lithification front has been observed and studied in detail to elucidate the timing of the establishment of overpressured conditions and its relation to changing diagenetic activity. The palaeo‐lithification front separates high‐porosity chalks above, that dominantly underwent mechanical compaction and contact cementation, from low‐porosity chalk below, that dominantly underwent severe pressure dissolution and pore‐filling cementation. Analysis of chalk buried under hydrostatic conditions shows a strikingly similar lithification front between 1000 and 1200 m burial, much shallower than the lithification front in the Danish Central Graben at a current depth between 2100 and 2400 m below seafloor. The discrepancy of 1200 m is due to the establishment of overpressured conditions that limited the increase in effective stress as burial continued, finally halting burial compaction when formation fluids started to carry the lithostatic weight. Basin modelling data indicate that this occurred at the end of the Oligocene for large parts of the Danish Central Graben, which is much earlier than the Middle Miocene timing that is currently assumed. The results imply a regional occurrence of a relict lithification front in the North Sea Basin, its position guided by stratigraphy, but mainly dependent on the maximum effective stress experienced during its burial history. The study shows that the porosity bipartition is a remnant of the past and not from ongoing compaction as has previously been suggested. Since it was established before the thermal maturity of the main source rocks, chalk below the lithification front must have formed a sealing unit during hydrocarbon migration. The recognition of the lithification front is also of importance to velocity modelling and depth‐conversion since a non‐linear increase between velocity and depth is expected across this boundary. The methodology may be applied in other overpressured basins where the diagenetic state of reservoir rocks at the end of hydrostatic conditions must be constrained.