The Vale of Pickering (VoP) in North Yorkshire has played host to several small gas discoveries that have come to the end of their production life. Now that the fields have ceased production, there is an opportunity to repurpose them and their infrastructure for the energy transition. Using an extensive, well-constrained seismic dataset, mapping of the VoP has revealed the presence of a NNE–SSW-striking Carboniferous basin precursor, the (newly defined) Slingsby Trough, containing Visean (syn-rift) organic shales that source the gas reservoirs and Namurian sandstones (post-rift) that form secondary reservoirs. Structural inversion of the half graben because of foreland deformation during the Variscan orogeny led to uplift, folding and peneplanation by the Base Permian Unconformity. The area was subsequently overlain by Upper Permian Zechstein Group carbonates and evaporites deposited on the margins of the Anglo-Polish Basin, creating the main reservoir–seal pair and a local petroleum system. Mesozoic faults striking ESE–WNW transected the area and created three-way, fault-bound footwall closures, forming a hydrocarbon ‘sweet-spot’ in the VoP through the coalescence of traps, a reservoir–seal pair and a mature source rock. This study improves our understanding of the various geological conditions that lead to its hydrocarbon prospectivity, explains why interest was shown in its unconventional resource potential, and provides a basis for evaluating the feasibility of re-imagining these fields as viable onshore storage and geothermal sites to aid the decarbonization of NE England.

The natural occurrence of carbon dioxide in subsurface reservoirs is proof of concept that it can be securely stored over geological timescales. Gas accumulations naturally enriched in CO 2 were identified in the East Irish Sea Basin, and their origin was evaluated using a large well and geophysical database. Legacy petroleum fluid samples indicate that CO 2 is regionally negligible, except within the proximal North Morecambe and Rhyl gas fields in the northern basin. Despite relatively elevated ionic concentrations within the northern basin, interpretations of CO 2 dissolution from formation water samples are not conclusive due to widespread contamination. Geochemical measurements of Carboniferous coal and shale samples indicate that units are typically mature and are lacking any further generative potential. While the accumulated CO 2 may have been generated from Carboniferous limestones or formerly organic-rich units, this is likely to have been limited based on their burial history and widespread extent compared to the local present-day distribution of CO 2 . Instead, thick and densely spaced Paleogene igneous dykes were mapped near the Rhyl Field. Despite being the most likely origin, igneous intrusions are interpreted across the northern basin and near several accumulations that lack CO 2 , suggesting that other geological elements have influenced its contemporary distribution, such as the cap rock or migration.

Constraining the age of formation and movement along fault arrays in superimposed basins helps us to better unravel their kinematic history as well as the role of bounding faults or inherited structures in basin evolution. The Inner Moray Firth Basin (IMFB, western North Sea) comprises a series of superimposed basins overlying rocks of the Caledonian basement, the pre-existing Devonian-Carboniferous Orcadian Basin and a regionally developed Permo-Triassic North Sea basin system. The IMFB rifting occurred mainly in the Upper Jurassic – Lower Cretaceous after a long period of subsidence followed by localised uplift in its eastern parts due to thermal doming in the central North Sea (in the middle Jurassic). The rift basin later experienced further episodes of regional tilting, uplift and fault reactivation during Cenozoic. New detailed field observations augmented by drone photography and creation of 3D digital outcrops, coupled with U-Pb geochronology of syn-faulting calcite-mineralised veins are used to constrain the absolute timing of fault movements and decipher the kinematic history of basin opening. It also helps to identify those deformation structures associated with earlier basin-forming events. Five regional deformation events emerge: Devonian rifting associated with the older Orcadian Basin; Late Carboniferous inversion related to dextral Great Glen fault movements; Permian thermal subsidence with some evidence of minor fracturing; Late Jurassic – Early Cretaceous rifting and Cenozoic reactivation and local inversion. We were also able to isolate characteristic structures, fault kinematics, fault rock developments and associated mineralisation types related to many of these events.

Devonian rocks of the Palaeozoic Orcadian Basin are well exposed along the northern flanks of the younger Mesozoic to Cenozoic Inner Moray Firth Basin in Scotland. These rocks preserve a succession of structures related to superimposed rifting and inversion events spanning nearly 400 Myrs. We combine new detailed field observations augmented by drone photography and the creation of 3D digital outcrops, coupled with U-Pb geochronology of syn-faulting calcite-mineralized veins to better constrain the absolute timing of fault movements and decipher the kinematic history of basin opening and inversion.Using this approach, we were able to isolate characteristic structures, fault kinematics, fault rock development and associated mineralization types related to five regional deformation events: (1) Devonian transtensional rifting associated to sinistral Great Glan Fault movements leading to the development of the Orcadian Basin; (2) Late Carboniferous inversion related to dextral Great Glen Fault reactivation; (3) minor N-S, possibly Permian calcite veins; (4) Late Jurassic–Early Cretaceous rifting related to the development of the IMFB; and finally, (5) Cenozoic uplift, reactivation, and local inversion. Our study demonstrates the utility of microstructurally constrained U-Pb geochronology of fault-related calcite mineralization. Applied elsewhere, our methodology has the potential to give consistent and regionally significant new insights into the nature and timing of superimposed rift-related deformation processes worldwide.

The Lower Triassic Bunter Sandstone Formation is a major prospective reservoir for carbon capture, utilization and storage in the UK Southern North Sea, and is likely to play a pivotal role in the UK reaching mid-century Net Zero targets. A knowledge gap in reservoir quality exists between previous detailed, but highly focused front-end engineering and development projects, and large-scale regional analysis. This study integrates a regional approach with locally derived reservoir characterization, offering a holistic analysis of the prospectivity of the Bunter Sandstone Formation for subsurface CO 2 storage. Petrophysical analysis of ninety-six wells across the UK Southern North Sea is coupled with seismic interpretation to understand spatial variations of reservoir thickness, facies and quality that underpin theoretical CO 2 storage capacity models. Electrofacies classification is employed to identify and correlate baffles and barriers to permeability over areas currently licensed for geological carbon storage. Our findings point to variable, but broadly favourable reservoir conditions, though identification and correlation of laterally extensive intraformational mudstones and halite-cemented horizons will likely present challenges to CO 2 injection. Within carbon storage license blocks CS001, CS006 and CS007, the Bunter Sandstone Formation has the potential to store 5700 MCO 2 t, the equivalent of seventy-nine years of the UK's 2022 business and industrial CO 2 emissions. A further 434 MCO 2 t is offered by Triassic closures within license CS005, with many neighbouring moderate (100–1000 MCO 2 t) and small (<100 MCO 2 t) closures forming part of newly awarded carbon storage licenses that will likely form part of the UK SNS CCUS portfolio in the future. Supplementary material: well-correlation panels and tabulated velocity and storage capacity modelling parameters are available at https://doi.org/10.6084/m9.figshare.c.7027450

Seismic interpretation has revealed a hitherto unreported honeycomb pattern of carbonate buildups within the Orchard Platform (Southern North Sea). The Z2 Stassfurt Halite Fm. onlaps the southern margin of the Orchard Platform and is also found infilling Z2 intra-platform lagoons to form salt lakes. Post Z2 evaporation, the deeper Z3 water column drowned the Orchard Platform inhibiting the platform recovery attempted by the Z3 Plattendolomit Fm. The palaeobathymetric variability of the drowned Orchard Platform was sufficient to bring parts of the seafloor into the photic zone allowing for the sporadic growth of the Z3 Plattendolomit Fm. However, the palaeobathymetric lows remained beneath the photic zone ensuring an incomplete regeneration of the Orchard Platform with the creation of a high-frequency network of intra-platform lagoons which mimic the polygonal texture of a honeycomb. Whilst previously accepted as collapse structures or karst systems, this study correlates the development of the honeycomb buildups to variations in seafloor palaeobathymetry which in turn mimic the structural lineaments of the Zechstein subcrop. Syn-depositional instability in the Zechstein subcrop caused the topsets of the Z2 salt lakes to become warped. The warped halite provided seed points for Z3 Plattendolomit Fm. growth which allowed for linear ridges of carbonate to traverse the Z2 salt lakes and eventually connect with the honeycomb buildups. Deposition in the Mesozoic lead to loading of the Zechstein. Halite-filled Z3 lagoons accommodated this loading, which caused a pinching effect on the Z3 honeycomb buildups. The sedimentological understanding provided by this study not only de-risks frontier exploration but also provides insight into carbonate growth in restricted platform recovery scenarios.

Previous basin modelling of the Faroe–Shetland Basin (FSB, offshore UK) has suggested mid-Cretaceous petroleum generation, which predates the deposition of the working Paleogene reservoirs and traps. To justify the time discrepancy between generation, reservoir, and trap formation, factors such as intermediary accumulations and overpressure have been invoked. However, across much of the FSB, the Cretaceous sequences that overly the Kimmeridgian source rock are heavily intruded by Paleogene-aged intrusions. Recent modelling has shown that the emplacement of the intrusions, coupled with lower radiogenic heat production from underlying basement, leads to estimates of petroleum generation occurring up to 40 myr more recently than suggested by previous models. In this work, we seek to better understand the role that igneous intrusions have exerted on petroleum generation and migration in the FSB. Models with varying thicknesses of Paleogene intrusions are compared with those that consider the Cretaceous sequence as purely sedimentary (i.e. similar to assumptions in previous modelling). The estimated times of petroleum generation are compared with geochronological constraints on the ages of oils (i.e. c . 90–68 Ma) along with the deposition and formation of other petroleum system elements. By considering only the effect of igneous intrusions, the expulsion onset from the source rock is retarded by up to 12 myr. In addition, our models show the impact of the intrusions on petroleum saturation and migration, suggesting that intrusions have potentially compartmentalized the basin, trapping petroleum beneath or within the sill complex. Finally, our findings suggest that basin models in regions impacted by significant magmatism need to consider the impact of intrusions to more accurately constrain both petroleum generation and migration. Thematic collection: This article is part of the New learning from exploration and development in the UKCS Atlantic Margin collection available at: https://www.lyellcollection.org/topic/collections/new-learning-from-exploration-and-development-in-the-ukcs-atlantic-margin

The Mid North Sea High (MNSH) Seaway, otherwise known as Jenyon's Channel, was the only major marine connection between the Northern and Southern Zechstein Basins during the latest Permian. Current understanding favours a model where marine replenishment began with a northern connection to the Panthalassic Ocean (along a network of basins that were precursors to the North Atlantic Rift System), after which marine water passed into the Northern Zechstein Basin, travelled through the MNSH Seaway before finally reaching the Southern Zechstein Basin. This study delineates evaporite formations in an extensive petrophysical dataset to analyse marine connections and whether they influenced Zechstein facies distribution. The first four Zechstein Cycles (Z1-Z4) are identified on the MNSH platform which shows that this structure was always covered by a thin water column during sea-level highstand; however, during Z2 sea-level lowstand, the MNSH Seaway provided the main connection between the basins. As relative sea-level fell, the MNSH Seaway became increasingly constricted resulting in hypersalinity due to limited volumes of marine water reaching the Southern Zechstein Basin. This system precipitated vast volumes of Z2 (late Wuchiapingian) halite in the Southern Zechstein Basin, whereas this facies remains reduced in the Northern Zechstein Basin. In Z3 and Z4 (Changhsingian) times relative average sea-level was higher resulting in sustained communication between the basins, even in times of sea-level lowstand. This is evidenced through a regionally traceable blanket of Z3 halite, along with occasional examples of Z2 carbonate platforms becoming entombed in Z3 halite. This work provides revised palaeoenvironmental understanding for the latest Permian. The workflow could also aid in the study of other oceanic gateways with further implications for hydrocarbon exploration efforts and emerging energy transition technologies such as subsurface storage on the UK Continental Shelf.

Summary This study addresses "Jenyon's Channel", which was an active seaway in the latest Permian with great control on Zechstein facies distribution in the North Sea. We investigate this feature, and provide evidence for how this system will influence Zechstein hydrocarbon exploration on the Mid North Sea High. After regionally characterising the carbonate and evaporite subunits of the Zechstein in publicly available petrophysical data, we discuss mechanisms which contributed to reservoir characteristics, compartmentalization, and potential seals. Ultimately, a regional understanding of the Zechstein allowed facilitated the creation of an updated palaeoenvironmental model for the Zechstein of the Mid North Sea High.

Summary Using a variety of open-access and proprietary subsurface datasets available through the UK Onshore Geophysical Library (UKOGL), our interpretations have shown that two different structural styles characterise the sub- and supra-salt sections in the Cleveland Basin, NE England, the creation of which are heavily affected by evaporite thickness and lithological composition in the Permian Zechstein. Towards the south-west in the Vale of Pickering, the basin experienced a net extensional stress regime as a result of Mesozoic rifting, creating a series of synthetic-antithetic normal faults that propagate towards the surface and detach down at the Permian Zechstein. Meanwhile towards the north-east in Ebberston, the basin is in a net compressional stress regime as a result of Cenozoic inversion, creating a fold-and-thrust belt that only affects the Paleozoic section up to and including the Z2 halite, which is thicker in Ebberston as a result of its more basinal paleoenvironment. As a result, the Mesozoic experienced little to no faulting and was only gently folded to accommodate for the underlying Paleozoic fold-and-thrust belt. The study's outcome has enabled us to understand the various geological options that will help decarbonise the industrial clusters in NE England.

As the United Kingdom reduces its CO 2 emissions in order to meet its 2050 net zero greenhouse gas targets, there will be a significant evolution of the UK's energy mix. The reliance on hydrocarbons will decrease while there is predicted to be an increase in low carbon energy sources such as renewables and nuclear. In order to decarbonise and achieve the net zero emissions targets while concurrently producing enough energy to provide for national energy needs, large‐scale, low carbon energy generation projects need to be developed alongside energy storage facilities to provide flexibility within a low carbon energy supply. Robust CCUS programmes will need be developed in order to capture and store unavoidable carbon dioxide emissions. The subsurface geology of the UK provides opportunities for the development of low carbon energy generation, energy storage and CCS, and the Upper Permian Zechstein Supergroup deposited in eastern England and offshore in the Southern North Sea is a potential host for these new developments. In NE England, salt cavern gas storage sites have been developed in thick Zechstein evaporites since the mid 20th centrury. In this paper we present new isopach maps and well correlation panels which will help to outline optimal locations for the development of additional salt caverns for gas storage. A review of the Zechstein Supergroup indicates that it does not exhibit great potential for the development of CCS, due both to its complex reservoir characteristics and to difficulties with both subsurface imaging and monitoring. However thick Zechstein evaporites could provide an excellent seal for CO 2 storage in the underlying Lower Permian Rotliegend Group.

The Upper Permian Zechstein Supergroup has the potential to play an important role in the UK's future energy production and energy transition. However the Supergroup is comparatively poorly understood in the UK, particularly the link between the onshore and offshore geology. In this paper we re‐evaluate available data in order to present a consistent regional interpretation of the Z1 to Z3 Zechstein Supergroup cycles. This review is based on an interpretation and re‐evaluation of 620 offshore wells located in the UK portion of the SW Southern North Sea and 83 onshore wells located in Yorkshire and Lincolnshire (eastern England). The Zechstein Supergroup was interpreted in each well, and the data was used to compile seven SW‐NE oriented correlation panels which show the development of the Supergroup in the study region. Five isopach maps for key formations in the Zechstein Supergroup were created, together with depositional environment maps for each of the main Zechstein carbonate formations. In combination, these regional‐scale maps and diagrams have resulted in a consistent interpretation of the Zechstein Supergroup over an area which extends from the onshore outcrop in the west to the UKCS boundary in the Southern North Sea in the east.

The Anglo-Polish Super Basin forms an important petroleum prov-ince that stretches across northwestern Europe. It contains many giant gas fields, primarily located beneath a thick upper Permian (Zechstein Group) evaporite canopy and a smaller amount of oil and gas in Mesozoic reservoirs in the suprasalt section. Although exploration activity continues in the super basin, discoveries have diminished in size; many fields have been decommissioned; and it is beginning a transformation from an area with a rich petroleum heritage to a new, low-carbon energy hub. Given its favorable geol-ogy, infrastructure, and the location of major industrial emitters in adjacent land areas, offshore parts of the super basin are being eval-uated and repurposed for renewable technologies like wind and geothermal energy, and as possible sites for subsurface carbon diox-ide, hydrogen, compressed air, and methane gas storage.The use of a rich, dense, and high-fidelity seismic, well log, core, and pressure data sets acquired during petroleum exploration and production activities provide the basis for a play-based explora-tion assessment of the super basin's carbon storage potential. The results of our analysis of the super basin's offshore waters of the United Kingdom sector suggest that storage in traps containing Carboniferous and Permian (presalt) and Triassic (postsalt) clastic reservoirs have the potential to extend the life of the mature super basin during the energy transition. The detailed evaluation of the Rotliegend Group, from which most of the gas in the basin has been derived, enables a prospective subsalt carbon storage reservoir play fairway to be defined, common risks to be identified, and composite maps to be produced that show where the best storage locations are situated. Similarly, mapping of depleted fields and dry closures created by salt mobility (halokinesis) that contain Triassic Bacton Group (Bunter Sandstone Formation) reservoirs provides the basis on which to build a carbon storage prospect and lead inventory in the suprasalt section. In addition to the geological cri-teria, our results highlight the need to be aware of nongeological risks including the integrity of the legacy well stock and colocation issues that arise from the competition for offshore areas, especially wind farms fixed to the sea bed, since these can constrain the areas available for carbon storage that lie below them.

Like many rift basins worldwide, the Inner Moray Firth Basin (IMFB) is bounded by major reactivated fault zones, including the Helmsdale Fault and the Great Glen Fault (GGF). The Jurassic successions exposed onshore close to these faults at Helmsdale and Shandwick preserve folding, calcite veining and minor faulting consistent with sinistral (Helmsdale Fault) and dextral (GGF) transtensional movements. This deformation has been widely attributed to Cenozoic post-rift fault reactivation. Onshore fieldwork and U–Pb calcite geochronology of five vein samples associated with transtensional movements along the Helmsdale Fault and a splay of the GGF show that faulting occurred during the Early Cretaceous ( c. 128–115 Ma, Barremian–Aptian), while the Helmsdale Fault preserves evidence for earlier Late Jurassic sinistral movements ( c. 159 Ma, Oxfordian). This demonstrates that both basin-bounding faults were substantially reactivated during the episodic NW–SE-directed Mesozoic rifting that formed the IMFB. Although there is good evidence for Cenozoic reactivation of the GGF offshore, the extent of such deformation along the north coast of the IMFB remains uncertain. Our findings illustrate the importance of oblique-slip reactivation processes in shaping the evolution of continental rift basins given that this deformation style may not be immediately obvious in interpretations of offshore seismic reflection data. Supplementary Material: Appendix A – orthomosaic model obtained from unmanned aerial vehicle (UAV) photography of the Helmsdale locality (GeoTiff format); Appendix B – orthomosaic model obtained from UAV photography of the Shandwick locality (GeoTiff format); Appendix C – geochronology data; and Appendix D – additional thin section microphotographs of sample HD1 showing repeated cycles of syntaxial grain growth are available at https://doi.org/10.6084/m9.figshare.c.6708518

Depleted hydrocarbon fields in the Liverpool Bay area of the United Kingdom East Irish Sea have been earmarked as sites for the geological storage of CO2. Cessation of production at the Hamilton field means that it will soon be available for storage and has led to its inclusion in the United Kingdom's first (track 1) car-bon capture, utilization, and storage cluster sequencing that underpins efforts to decarbonize onshore emitters (HyNet pro-ject). The interpretation of well-calibrated, proprietary three-dimensional seismic data has enabled critical assessment of the geological controls on CO2 storage in the area. Our mapping demonstrates that significant portions of the fields lie shallower than the 800-m depth threshold, above which lower pressures and temperatures prevent CO2 from being stored in the most efficient supercritical phase, significantly reducing storage capac-ity during the early phases of injection. Furthermore, an assess-ment of the Mercia Mudstone Group seal highlights the presence of a gas-bearing basal Ansdell Mudstone Member to the Orm-skirk Sandstone Formation reservoirs forming a waste zone that extends the reservoir section to even shallower levels. The map-ping of faults to near seabed and progressive younging and shal-lowing of the ultimate top seal resulting from a progressive pinch-out of halite horizons in the Mercia Mudstone Group raise additional questions about the integrity of the top seal in south-ern parts of the basin. Taken together, our results flag a number of technical issues, cast some geological doubt on, and highlight a need to understand the impacts of using fields in Liverpool Bay for carbon storage upon which the HyNet project depends.

The separation and characterisation of different deformation events in superimposed basins can be challenging due to the effects of overprinting and/or fault reactivation, combined with a lack of detailed geological or geophysical data. This study shows how an onshore study can be enhanced using a targeted interpretation of contiguous structures offshore imaged by seismic reflection data. Two deformation events, including unambiguous evidence of fault reactivation, are recognised in the onshore part of the Lossiemouth Fault Zone (LFZ), southern-central Inner Moray Firth Basin. The basin is thought to record a history of (possibly) Permian to Cenozoic deformation, but it is commonly difficult to conclusively define the age of faulting and fault reactivation. However, structures in Permo-Triassic strata onshore outcrops show no evidence of growth geometries and new interpretation of seismic reflection profiles offshore reveals that Permo-Triassic fills are widely characterised by subsidence and passive infill of post-Variscan palaeotopography. We propose that sequences of reactivated faulting observed onshore and offshore can be correlated and can be shown in the latter domain to be early Jurassic-late Cretaceous, followed by localised Cenozoic reactivation. The workflow used here can be adapted to characterise deformation events in other superimposed rift basins with contiguous onshore surface-offshore subsurface expressions.

In this study, we investigate the tectonic and stratigraphic evolution of the northern Tanzania margin (western Indian Ocean) to provide new insights on the structural drivers governing the formation of Zanzibar and Pemba islands. Using 2D seismic reflection profiles and exploration wells, we have reconstructed the evolution of the submarine drainage network throughout the last 30 Myr, from the Oligocene to recent times, providing a tape-recorder with which we determine the different tectonic events that led to the eventual subaerial exposure of the islands. In detail, we observe a decrease in the number of slope canyon-channel systems during the lower-middle Miocene offshore Pemba Island that we interpret to represent the initial uplift of the island: tectonic deformation of the seafloor impeded up-dip to down-dip sediment transfer, forcing the abandonment of canyon-channel systems. At the same time, submarine canyons were still active offshore Zanzibar Island, located similar to 35 km south of Pemba, indicating that its uplift occurred later, likely during the upper Miocene to lower Pliocene. The changes in seafloor topography and slope gradient promoted the formation of two newly discovered giant canyons that represent the main feeder systems to this sector of the western Indian Ocean since the Miocene. We propose a new conceptual model for the post-Oligocene evolution of the area, highlighting the main tectonic structures and their timing of formation. In this model, the onset of the anticlines of Pemba and Zanzibar islands resulted from tectonic inversion probably originated during the Oligocene-lower Miocene due to reactivation of Mesozoic-aged rift faults. This compressional phase is followed by the establishment of an extensional tectonic regime which promoted the subaerial exposure of the islands since the middle Miocene. Extensional faults, which dissect the post-Oligocene stratigraphy, create horsts and grabens on a variety of scales, such as Zanzibar and Pemba troughs. These grabens show comparative size and orientation to onshore rift basins, which may indicate a relation with the tectonics of the East African Rift System. Our results provide new insights on the evolution of one the least explored, though fascinating, continental margin settings worldwide that can support future source-to-sink investigations in the region.

The Inner Moray Firth Basin (IMFB) forms the western arm of the North Sea trilete rift system that initiated mainly during the Late Jurassic–Early Cretaceous with the widespread development of major NE–SW-trending dip-slip growth faults. The IMFB is superimposed over the southern part of the older Devonian Orcadian Basin. The potential influence of older rift-related faults on the kinematics of later Mesozoic basin opening has received little attention, partly owing to the poor resolution of offshore seismic reflection data at depth. New field observations augmented by drone photography and photogrammetry, coupled with U–Pb geochronology, have been used to explore the kinematic history of faulting in onshore exposures along the southern IMFB margin. Dip-slip north–south- to NNE–SSW-striking Devonian growth faults are recognized that have undergone later dextral reactivation during NNW–SSE extension. The U–Pb calcite dating of a sample from the synkinematic calcite veins associated with this later episode shows that the age of fault reactivation is 130.99 ± 4.60 Ma (Hauterivian). The recognition of dextral-oblique Early Cretaceous reactivation of faults related to the underlying and older Orcadian Basin highlights the importance of structural inheritance in controlling basin- to sub-basin-scale architectures and how this influences the kinematics of IMFB rifting. Supplementary material: Analytical protocols and analysed sample details are available at https://doi.org/10.6084/m9.figshare.c.5635432