The importance of precipitation rate as an effective control on illite and kaolanite formation during diagenesis has been examined by measuring precipitation rates, from Al fluid concentration, in a Dickson fluid-sampling vessel at 160°-250° and 500 bars (50 MPa). These experiments are considered to be analogues of the precipitation of clays in sandstones from porewaters containing dissolved carboxylic acids, which have a transient stability and may influence aluminosilicate solubility. Precipitated illite had a lath-shaped morphology and its composition was consistent with authigenic illite in sandstones. Kaolinite formed tabular rather than vermicular shaped crystals. Kaolinite precipitation rate was two orders of magnitude faster than illite precipitation and was rate-limited by the decomposition of oxalate; kaolinite formation should be equilibrium-controlled at virtually all stages of burial. Extrapolation of illite precipitation rate to burial temperatures indicates that the first appearance of illite in a burial sequence may be kinetically controlled. A model of illite precipitation based on these experimental results has been used to predict the time required to precipitate illite during burial of a sandstone, taking into account temperature changes during burial. For northern North Sea examples, a predicted illitization threshold of -60°C occurring at 60–80 Ma corresponds to the observed initiation of authigenic illite precipitation. Times of around 2–5 Ma would be required to reach a 98% approach to equilibrium at this threshold. The main phase of illite precipitation in the northern North Sea basin is a later, hydrologically controlled event (30-50 Ma). Equilibrium would be approached in around 0.1 Ma during this phase, which is consistent with the narrow illite K/Ar age range (1-5 Ma) recorded for some sequences.

The nature, composition, and relative abundance of clay minerals in the sandstones of the Brent Group reservoir were studied between 3200–3300 m in a well of the Ellon Field (Alwyn area, North Sea). The sandstones have a heterogeneous calcite cement which occurred during early-diagenesis. Clay diagenesis of the cemented and uncemented sandstones was investigated using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction analyses (XRD), and infrared spectroscopy (IR). The influence of cementation on clay neoformation is demonstrated in this study. Detrital illite and authigenic kaolinite are present in both the calcite-cemented and uncemented sandstones suggesting that kaolinite precipitated before calcite cementation. In the uncemented sandstones, blocky dickite replaces vermiform kaolinite with increasing depth. At 3205 m, authigenic illite begins to replace kaolinite and shows progressive morphological changes (fibrous to lath-shape transition). At 3260 m, all sandstones are not cemented by calcite. Illite is the only clay mineral and shows a platelet morphology.

In the cemented samples, vermiform kaolinite is preserved at all depths, suggesting that dickite transformation was inhibited by the presence of the calcite cement. This observation suggests that calcite cement would prevent fluid circulation and dissolution-precipitation reactions.

Illite-smectite (I-S) minerals isolated from Upper Jurassic oil-source rock shales from Denmark and the North Sea have been investigated by X-ray diffraction, thermal analysis, infrared, Mössbauer, and solid-state nuclear magnetic resonance spectroscopies and chemical analysis. Detailed structures have been determined in order to reveal the diagenetic transformation mechanism in these shales. Generally, in oil-source rocks of sedimentary basins, oil generation takes place simultaneously with the diagenetic transformation of I-S. We demonstrate a link between the two reactions: NH3 released from kerogen during maximum oil generation is fixed as NH4+ in the NH4-bearing mica or tobelite layers formed from smectite or vermiculite layers in I-S, in a diagenetic interval which we name the ‘tobelitization window’. Due to this solid-state transformation, mixed-layer structures have been formed consisting of interstratified illite, tobelite, smectite and vermiculite layers (I-T-S-V) and having maximum ordering of illite + tobelite and smectite layers for R = 1. The tobelitization of smectite in I-S is probably typical for all oil-source rock shales.

Upper Cretaceous—Danian chalk and interbedded clay-rich layers from wells of the South Arne Field and adjacent wells in the North Sea and from Stevns in Zealand have been investigated to determine the clay mineralogy in the chalk and the origin of the interbedded clay-rich layers. The mineralogy, with emphasis on clay mineralogy, was determined after removal of the calcite by dissolution at pH 4.5–5 in order to preserve the other minerals. Generally, mixed-layer minerals are the dominant clay minerals, except for two wells, Rigs-1 and Rigs-2, where a 3D ordered kaolinite prevails. A detailed structural characterization of the mixed-layer minerals was carried out by modeling of the X-ray diffraction (XRD) patterns. In most of the samples dominated by mixed-layer minerals, two mixed-layer phases, a high-smectite illite-smectite (I-S) and a low-smectite illite-smectite-chlorite (I-S-Ch), prevail, irrespective of depth or location of the samples. However, some samples contain I-S-Ch and ordered S-Ch, and others a chlorite-serpentine (Ch-Sr) phase, and these samples probably formed during diagenesis at higher temperatures. The clay-rich layers and the adjacent chalk have the same or quite similar clay mineralogy, both with respect to kaolinite vs. mixed-layer minerals and with respect to their detailed structure. In conclusion, the kaolinite is detrital and the I-S minerals formed in the chalk from volcanic ash. The main conclusion is that the clay-rich layers in the North Sea chalk formed by dissolution of the calcite in the chalk and that this dissolution took place at burial depths of >1 km, probably through migration of solutions through permeable chalk layers.

The Palaeolithic archaeological record from current dryland contexts informs on activity across only a fraction of occupied Pleistocene landscapes. Now-submerged contexts, such as those preserved beneath the southern North Sea, allow past human activity to be considered at a more representative scale. Previous investigations have recovered internationally significant Middle Palaeolithic archaeology associated with submerged Pleistocene landscapes in the southern North Sea. Discovered through aggregate dredging in marine aggregate licence Area 240, the archaeology is associated with Pleistocene deposits of the Paleo-Yare river system. Subsequent studies have demonstrated that the Palaeo-Yare catchment extended across adjacent aggregate areas, leading to the implementation of a regional monitoring programme at aggregate wharfs to monitor, manage, and assimilate new archaeological data.

This paper reviews all new Palaeolithic lithic finds recovered between 2011 and 2022 from Area 240 and adjacent licence areas. Most are Middle Palaeolithic artefacts from Area 240. These new Middle Palaeolithic discoveries are related to previous finds and the combined collections placed within their wider Middle Palaeolithic British context. Middle Palaeolithic activity within the Palaeo-Yare catchment included multiple phases of occupation associated with different favoured technological repertoires, indicating that two groups of artefacts are present: Levallois artefacts likely to date to the early Middle Palaeolithic (MIS 8–7–6) and handaxes dating to the Late Middle Palaeolithic (MIS 5d–3).

Despite holding the accolade as the largest animal ever to live on planet earth and ubiquitously inhabiting the world's major oceans, an acute paucity of information surrounds the geographical distribution and migration phenology of the endangered blue whale (Balaenoptera musculus) in the northeast Atlantic. Current migration and distribution information derived from robust scientific studies is required to ensure the formulation and implementation of successful conservation measures with a vision to support the ongoing recovery of the northeast Atlantic population. At 10:21 (UTC) on the 9th of November 2020, two blue whales were observed at position 55°13.99′N, 01°13.62′W, 18 km off the coast of the UK in the central North Sea just north of Newcastle at a water depth of 76 m. This is the first paper that has confirmed an account of live blue whales frequenting shallow waters of the central North Sea and represents a new area of occurrence within the accepted range of the northeast Atlantic population, an area in which sightings are extremely rare and may provide insight into the intricacies of migration routes and behaviour.

The North Sea is considered a unique heritage site that yielded a huge amount of zoological and archaeological data. More than 200 palaeozoological and archaeological fossil bone samples from the North Sea bed are dated by 14C. About 2/3 of these dated bones are Pleistocene in age; the majority of the bones are from extinct species (in particular woolly mammoth); about 1/3 of the sample date to the Holocene. The presented dataset is important in its kind, but interpretation is limited because of a lack of context of the finds. The stable isotopes (13C, 15N) of the dated samples provide additional information on palaeoenvironmental conditions and dietary habits in the past. We present primarily a Groningen list of data; a few fossils dated in other laboratories are included for completeness.

On 19 July 2019 an estimated 20 bottlenose dolphins (Tursiops truncatus) were observed in the Marsdiep, a tidal inlet connecting the North Sea and the Dutch Wadden Sea, between Den Helder and the island of Texel. Photographs and video recordings were made and nine individuals were matched with known dolphins from the Moray Firth, NE Scotland. These are the first matches of this east coast of Scotland population outside the UK and Ireland. Subsequent observations of individuals from this group show that at least some of the animals have returned to Scottish waters, while others were photographed in Danish waters. Furthermore, we report on a photo identification match of a solitary bottlenose dolphin between France and the Netherlands. These matches suggest that bottlenose dolphins, in the Netherlands, originate from two different genetically distinct populations: ‘Coastal South’ and ‘Coastal North’. This evidence of previously unknown long-range movements may have important implications for the conservation and management of this species in European waters.

The Holocene sea-level rise has led to significant changes in present-day coastal zones through multifold retrogradational and slightly progradational displacements of the mainland coastline. During the course of this postglacial transgression, sediments characteristic of coastal environments accumulated first in palaeovalleys of the pre-Holocene landscape and later on the subsequently developed coastal plain. Based on a compilation of sedimentological, lithological and litho-chronostratigraphical data of more than 1200 sediment cores, we generated four palaeogeographic maps of the coastal zone of the central Wadden Sea to document with a high spatial resolution the landscape changes during characteristic phases of the Holocene sea-level rise, i.e. the periods 8600–6500 cal BP, 6500–2700 cal BP, 2700–1500 cal BP and 1500–1000 cal BP. Along three cross-sections, representing different hydrodynamic conditions and exposure, we exemplify how the Holocene landscape development and sedimentary facies types are controlled by the local palaeorelief, sea-level changes, sediment supply, accommodation space, the morphodynamic impact of channel shifts, and their erosion base. This leads to a better understanding of main factors controlling the local depositional processes of the coastal landscape along the central Wadden Sea during the Holocene transgression.

The 1717 Christmas flood is one of the most catastrophic storm surges the Frisian coast (Netherlands and Germany) has ever experienced. With more than 13,700 casualties it is the last severe storm surge with a death toll of this order. At the same time, little is known about the hydrodynamic conditions and the morphological effects associated with this storm surge.

In this study, 41 potential dyke failures in the Province of Groningen (Netherlands) associated with the 1717 Christmas flood were systematically reconstructed and mapped by using historical maps and literature and by analysing the recent topography in search of typical pothole structures and sediment fans. The dimensions of the sediment fans as derived from the topography show a good accordance with the dimensions documented by vibracore profiles, direct push tests and electrical resistivity tomography data taken at three fieldwork sites. Moreover, the fan dimensions closely agree with the dimensions as simulated using a process-based morphodynamic numerical model for one of the three sites, the village of Wierhuizen. Consequently, the recent topography is still indicative for the locations and dimensions of dyke failures and sediment fans associated with the 1717 Christmas flood. Considering the large number of detected dyke failures (41) and the large dimensions of the potholes and particularly of the sediment fans up to a few hundred metres wide and up to 0.7 m thick, this study proves significant morphological effects of the 1717 Christmas flood on the mainland of the Province of Groningen.

Based on the numerical simulation approach and the comparison with field data and field observations, a maximum seaward water level of 5 m NAP for the dyke failure at Wierhuizen during the Christmas flood can be derived. A similar maximum water level is indicated for the two other fieldwork sites Vierhuizen and Kohol, which is in good agreement with the maximum storm surge level of 4.62 m NAP historically documented for the city of Emden located almost 50 km to the east of Wierhuizen.

The results of the current study demonstrate that the reconstruction of historical dyke failures based on (i) historical sources, (ii) recent lidar/high-resolution topographical data, (iii) multi-proxy sedimentary field data and (iv) hydro- and morphodynamic numerical simulations is a highly promising approach to derive hydrodynamic conditions and the morphological onshore response of the 1717 Christmas flood in the Province of Groningen. This knowledge is essential to improve our understanding of extreme storm surge dynamics, their influence on the coastal landscape and the associated hazards for the coastal population.

Size-frequency analysis of the echinoid Echinocyamus pusillus from six offshore areas in the southern North Sea and eastern English Channel reveal five distinct cohorts, suggesting a lifespan of five years. In all six individual areas one or more year-groups are absent, due to the unsuccessful recruitment of planktonic larvae to the seabed in some years, giving a false impression of a shorter lifespan. A relatively long lifespan and planktotrophic larval development are remarkable for such a small species, which reaches a maximum test length of 7.3 mm in the area, such traits being more typical of large-sized macrobenthic species. The feeding mode is akin to that of many meiobenthic taxa. The architecture of the test confers exceptional strength and resilience to mechanical perturbation.

Whale strandings occur in many places worldwide and numerous possible explanations for this phenomenon have been proposed, including the effects of astronomical events such as Solar eruptions on the Earth's magnetic field. Whales use the geomagnetic field for navigation, and its distortion can therefore result in whale strandings in certain regions. However, Solar storms do not have the same impact on the geomagnetic field across the whole of the Earth's surface, and positions nearer to the equator are less exposed to this phenomenon. It is therefore plausible that Solar storms can explain whale strandings at high latitude at least, but not necessarily worldwide. This review considers strandings in relation to the geographical and geomagnetic properties of locations at higher latitudes and to changes in the magnetic field over recent centuries. It also focuses on a Solar storm in December 2015. These considerations suggest that navigation errors due to Solar storms are more likely to occur at higher latitudes, particularly in sea areas where the animals might subsequently swim into a geographic trap and become stranded. For sperm whales (Physeter macrocephalus), the southern Norwegian Sea in conjunction with the shallow North Sea represents such an area.

Modelling of surface and shallow subsurface data is getting more and more advanced and is demonstrated mostly for onshore (hydro)geological applications. Three-dimensional (3D) modelling techniques are used increasingly, and now include voxel modelling that often employs stochastic or probabilistic methods to assess model uncertainty. This paper presents an adapted methodological workflow for the 3D modelling of offshore sand deposits and aims at demonstrating the improvement of the estimations of lithological properties after incorporation of more geological layers in the modelling process. Importantly, this process is driven by new geological insight from the combined interpretation of seismic and borehole data. Applying 3D modelling techniques is challenging given that offshore environments may be heavily reworked through time, often leading to thin and discontinuous deposits. Since voxel and stochastic modelling allow in-depth analyses of a multitude of properties (and their associated uncertainties) that define a lithological layer, they are ideal for use in an aggregate resource exploitation context. The voxel model is now the backbone of a decision support system for long-term sand extraction on the Belgian Continental Shelf.