Basin Research - Volume 37, Issue 2, 2025

By means of seismic interpretations, this study provides improved constraints on a major Tournaisian (lowermost Carboniferous) tectonic phase with faulting across the Campine Basin, northeastern Belgium. Faults are normal with throws below 100 m, except for some larger intra‐rift horst and graben structures with throws up to 300 m. In an asymmetric graben structure in the southern study area, an estimated average of 1000 m of Tournaisian sediments accumulated. Outside the graben, Tournaisian thicknesses are in the order of 300–500 m, which agrees with the limited available well data outside the study area of the Campine Basin. There is an uncertainty on fault strikes since the individual fault segments are short compared to the spacing between the seismic lines, but we estimate it to vary between SW–NE and WNW–ESE. The wide range of fault strikes can be related to the reactivation of pre‐existing faults in the Cambro‐Silurian basement. The SW–NE and WNW–ESE directions of the Tournaisian fault strikes have been identified as lineaments on gravimetric and aeromagnetic maps of the lower Palaeozoic Brabant Massif to the southeast and southwest of the study area, respectively. Such fault strikes imply a roughly NNW–SSE to N–S extensional stress field prevailing in the area during the Tournaisian. The range of fault strikes is very similar to the strike of contemporaneous faults in Ireland and the United Kingdom, which suggests that the NNW–SSE to N–S extensional stress field occurred throughout much of northwestern Europe. The Tournaisian succession of the Campine Basin includes numerous mound‐shaped complexes, interpreted as buildup structures. We show examples of major buildup complexes that developed in graben structures. One of them reaches a height of 750 m and is 3 km wide. Given the similarity in timing of formation and size of the buildup complexes in the Campine Basin with buildup complexes in southern Belgium and Ireland, we consider it likely that the buildup complexes in the Campine Basin represent Waulsortian mudmounds.

By means of seismic interpretations, this study provides improved constraints on a major Tournaisian tectonic phase with normal faulting in the Campine Basin. Faulting was accompanied by the development of major buildup structures, probably Waulsortian mudmounds.

This study presents a detailed 3D lithofacies model of the Upper Pleistocene–Holocene Tiber Depositional Sequence (TDS) within the alluvial plain of Rome, Italy, developed using an integrated approach. A deterministic framework was used to establish 1D lithofacies constraints, while geostatistical algorithms, particularly indicator kriging, were employed to reconstruct the stacking patterns and interfingering of lithofacies within systems tracts. This methodology allows for the realistic depiction of depositional trends and stratigraphic architecture while addressing challenges posed by limited data density in unsampled locations. The resulting 3D model demonstrates its ability to honour observed data while enabling meaningful extrapolation of subsurface features. The model captures key evolutionary trends and aligns with the conceptual 2D stratigraphic reconstruction developed in this study and the sequence‐stratigraphic framework of the TDS derived from previous studies. Stratigraphic cross‐sections and 2D correlation profiles extracted from the 3D model reveal the depositional architecture and constrain the thickness and extent of primary lithofacies associations. Key findings include the identification of braided and meandering channel‐belt complexes associated with poorly and well‐drained floodplain deposits. The lowstand systems tract (LST) is characterised by extensive braided channel belts with high width‐to‐thickness ratios, while the transgressive systems tract (TST) exhibits vertically stacked meandering channels associated with poorly drained floodplains. The highstand systems tract (HST) shows increased channel clustering and lateral expansion of meandering channel belts, associated with well‐drained floodplain deposits displaying pedogenic features. The findings highlight the strengths and limitations of two‐point geostatistical algorithms, with indicator kriging outperforming traditional methods like Truncated Gaussian Simulation and Sequential Indicator Simulation in maintaining geological coherence and lateral continuity. The 3D model enhances our understanding of the Tiber alluvial basin evolution and provides a robust framework for urban geological applications. It serves as a pivotal tool for managing subsoil resources, mitigating geohazards, and preserving cultural heritage in densely populated areas. This approach demonstrates the feasibility of applying efficient, scalable techniques to model sedimentary successions in similar urbanised alluvial settings worldwide.

A 3D lithofacies model of the Upper Pleistocene–Holocene Tiber Depositional Sequence (TDS) was developed using an integrated sequence stratigraphy and geostatistical approach. Indicator kriging proved most effective in capturing stratigraphic architecture, providing a robust tool for geological mapping, resource management, and geohazard assessment in urban alluvial settings.

The Base Cretaceous unconformity in Southwest Britain, Iberia, and adjacent North Atlantic basins is a composite of at least three unconformities formed during the Middle Jurassic, Late Jurassic–Early Cretaceous, and Mid‐Cretaceous. Seismic data reveal that the Jurassic–Early Cretaceous unconformity, linked to Berriasian uplift and North Atlantic opening, was the most significant. Subsidence patterns vary across basins, with some controlled by thermal cooling and others influenced by Variscan thrust reactivation and sub‐plate support. These findings highlight the complex interplay of tectonics and denudation in shaping large‐scale unconformities.

Jurassic and Early Cretaceous times were marked by significant changes in Earth's climate and tectonics, most notably the breakup of the supercontinent Pangaea, which led to the opening of the Atlantic Ocean. In Southwest Britain, one of the most prominent features of this time is the Base Cretaceous unconformity representing widespread erosion and non‐deposition separating Cretaceous strata from underlying rocks. Despite its widespread presence in Southwest Britain, Iberia, Ireland and conjugate North Atlantic basins, the origin and nature of this unconformity remains enigmatic. To better understand its nature, seismic data was used to map the extent of the unconformities and to establish their relationships with onlapping Jurassic and Cretaceous stratigraphy. We reveal that the Base Cretaceous unconformity is a composite of at least three—Middle Jurassic, Late Jurassic to Early Cretaceous and Mid‐Cretaceous—unconformities likely generated by erosion and non‐deposition. The Mid‐Cretaceous unconformity is often assumed to be responsible for the majority of erosion, but our findings suggest otherwise. Onlap patterns of the Lower Cretaceous Wealden Formation on truncated Jurassic units indicate that the Jurassic to Early Cretaceous unconformity was the most significant. Amplitudes of uplift across different basins in SW Britain are shown to be variable. The most substantial denudation occurred following Berriasian uplift, likely linked to shortening associated with North Atlantic opening. The Mid‐Cretaceous unconformity is more subtle, primarily observed at basin margins and linked to the rift‐drift transition of the Bay of Biscay. Subsidence histories differ across basins; some (e.g., Brittany Basin) can be explained by simple post‐rift thermal cooling models, while others (e.g., Melville and South Celtic Sea Basins) require more complex explanations due to substantial missing stratigraphy, including reactivation of Variscan thrusts and sub‐plate support. Our results emphasise that spatially and temporally distinct tectonic and denudation events can combine to generate large‐scale composite unconformities.

In the Paleogene and with the docking of Siletzia on North America's western margin, the Georgia Basin transitioned from a forearc basin to a forearc depression, and this drove a major re‐organisation of depositional environments and paleodrainages in the region.

Outcrops of sedimentary strata that infill the Georgia Basin, Canada and USA have been studied extensively as they record information on the tectonic evolution of western North America. However, these outcrops are situated in only a limited extent of the basin (mainly Vancouver Island) and preserve mainly Upper Cretaceous strata, and so the information that can be derived from outcrops is incomplete and spans less than half of the Georgia Basin's temporal history. The majority of the Georgia Basin, and the complete stratigraphy, occurs in the subsurface in the Whatcom Sub‐Basin, which extends below much of the Strait of Georgia, the Lower Mainland of British Columbia (LMBC), Canada and northwest Washington, USA. In this study, we reconstruct the stratigraphic architecture, evolution and palaeogeography of Upper Cretaceous and Cenozoic strata in the Whatcom Sub‐Basin, and we use these data to develop a more complete record of the depositional history of the Georgia Basin and its evolution relative to major tectonic events along North America's west coast. We focus on the Canadian extent of the Whatcom Sub‐Basin, the LMBC, because of the availability of two‐dimensional seismic reflection datasets and cored intervals, which enable facies characterisation and provide detrital zircon datasets. The stratigraphy of the Whatcom Sub‐Basin is divided into four stratal packages, including: lower Nanaimo Group, upper Nanaimo Group, Huntingdon Formation and Boundary Bay Formation. The few outcrops and a single cored interval suggest that the lower Nanaimo Group is dominated by fluvial strata in the Whatcom Sub‐Basin. The upper Nanaimo Group is dominated by fluvial strata in the central part of the Whatcom Sub‐Basin and turbidites and deep‐marine strata in the west, and this facies relationship indicates that sediment transport was to the west. The Eocene and younger Huntingdon and Boundary Bay formations record re‐organisation of the basin, with a shift in sediment transport to the south and southwest. Both the Huntingdon and Boundary Bay formations are dominated by terrestrial strata with evidence of marine influence increasing towards the southwest but decreasing stratigraphically upwards. Changing sediment transport pathways and recycling of Nanaimo Group strata in Eocene time reflect the bifurcation of the Georgia Basin with uplift of the forearc high (i.e., Vancouver Island). Boundary Bay Formation deposits extend further east than do all other stratigraphic units, and detrital zircon‐based maximum depositional age estimates indicate that parts of the Lower Mainland probably have experienced active subsidence for at least the past 15 million years. A comparison of our data to tectonic events along North America's western margin indicates that (a) the fill and geometry of the basin evolved due to syn‐ and post‐depositional tectonism, and (b) basin topography and syntectonic activity drove major changes in depositional environments both areally and temporally. For example, uplift of the forearc high and the associated re‐organisation of drainages in the Whatcom Sub‐Basin correlate temporally to docking of Siletzia in the early Eocene.

The outcrops of the Panoche and Tumey Giant Injection Complexes in California have been instrumental in refining the interpretation of the sandstone intrusion reservoirs in the Volund Field, Norway. Insights from the outcrops enhanced the subsurface team's confidence and understanding of reservoir presence and connectivity during field production. This led to more accurate estimates of hydrocarbon reserves. Learnings from the Volund Field show that historical reservoir models underestimate net reservoir volume and reservoir connectivity. Outcrop data reveal step‐like geometry in some intrusions, which potentially explains the lack of seismic resolution of sandstone intrusions in some areas of the field. Failure to recognise this leads to misinterpretation of parts of the field as non‐reservoir. In some intervals, well logs interpreted as non‐reservoir mudstone‐rich units are actually mudstone‐clast breccia, which, because of good connectivity within the sandstone matrix, can comprise significant reservoir volumes. The rationale for including sandstone intrusions as reservoirs, although unresolved by seismic or borehole log data in static models, is validated by reference to outcrop data and from recent drilling in the adjacent Kobra Field. Observations of outcrop analogues enhance the interpretation of subsurface data, and the knowledge acquired from outcrops helped justify the drilling of more production wells in areas where reservoir presence and quality were difficult to predict, but almost nearly doubled the hydrocarbon reserves.