The chemical and mineralogical composition of rattlestones found near the main Dutch rivers has been studied by Mössbauer spectroscopy, INAA and XRD. Rattlestones are concretions of iron, formed in an environment of lateral iron accumulation, under the influence of periodical oxidation, around a fine core of ferruginous sediments, mainly clay and sand. The core has shrunk and detached itself from the mantle around it. 57Fe Mössbauer spectroscopy was applied to identify the iron oxides, among which goethite is predominant. The goethite crystallinity was investigated by measuring its magnetic properties and its crystallinity, which is poorest at the outer side of the stone. The latter is confirmed by the broadening of the different X-ray reflections. In addition, illite and vermiculite were identified by XRD; these clay minerals were found mainly in the core.

The elemental composition was determined by INAA. The iron content in the mantle is about 50% by weight and gradually decreases outwards, while the core contains 2–15% Fe by weight. Differences between rattlestones from the Middle Pleistocene East of the Meuse river and those from the Late Pleistocene North of it are the absence of lepidocrocite and a richer mineralogy in the former.

It is concluded that the rattlestones are formed around a fine clayey core. Groundwater supplied the iron and other (trace) elements for the genesis. It is unlikely that rattlestones are the result of oxidation of siderite.

Knowledge of habitat segregation of mosasaurs has been based on lithology and faunal assemblages associated with fossil remains of mosasaurs and stable isotopes (δ13C). These approaches have sometimes provided equivocal or insufficient information and, therefore, the preference of habitat by different mosasaur taxa is still suboptimally constrained. The present study is focused on the analysis of rare earth element (REE) ratios of mosasaur fossils from the Upper Cretaceous formations of western Alabama, USA. Results of the REE analysis are used to infer the relative paleobathymetry associated with the mosasaur specimens and then to determine if certain taxonomic groups showed a preference for a particular water depth. Comparisons are then made with mosasaur specimens reported in the literature from other regions of North America from different depositional environments. Results indicate that Mosasaurus, Platecarpus and Plioplatecarpus may have preferred more restricted habitats based on water depth whereas Tylosaurus and Clidastes favoured a wider range of environments. Results also suggest that Plioplatecarpus lived in a shallower environment than its Platecarpus predecessor. Although the results of this study are encouraging, caution must be exercised before drawing any final conclusions due to the small sample size of most of the taxa analysed.

We perform statistical analyses on spatiotemporal patterns in the magnitude distribution of induced earthquakes in the Groningen natural gas field. The seismic catalogue contains 336 earthquakes with (local) magnitudes above $1.45$ , observed in the period between 1 January 1995 and 1 January 2022. An exploratory moving-window analysis of maximum-likelihood b-values in both time and space does not reveal any significant variation in time, but does reveal a spatial variation that exceeds the $0.05$ significance level.

In search for improved understanding of the observed spatial variations in physical terms we test five physical reservoir properties as possible b-value predictors. The predictors include two static (spatial, time-independent) properties: the reservoir layer thickness, and the topographic gradient (a measure of the degree of faulting intensity in the reservoir); and three dynamic (spatiotemporal, time-dependent) properties: the pressure drop due to gas extraction, the resulting reservoir compaction, and a measure for the resulting induced stress. The latter property is the one that is currently used in the seismic source models that feed into the state-of-the-art hazard and risk assessment.

We assess the predictive capabilities of the five properties by statistical evaluation of both moving window analysis, and maximum-likelihood parameter estimation for a number of simple functional forms that express the b-value as a function of the predictor. We find significant linear trends of the b-value for both topographic gradient and induced stress, but even more pronouncedly for reservoir thickness. Also for the moving window analysis and the step function fit, the reservoir thickness provides the most significant results.

We conclude that reservoir thickness is a strong predictor for spatial b-value variations in the Groningen field. We propose to develop a forecasting model for Groningen magnitude distributions conditioned on reservoir thickness, to be used alongside, or as a replacement, for the current models conditioned on induced stress.

The province of Groningen is flat and level, lying at an elevation close to sea level. The area is intensely cultivated and water table levels are a matter of concern. When the size of the Groningen gasfield was recognized in the sixties, it was realized, that substantial subsidence might occur at the surface affecting a large area.

Intensive studies were performed over time to predict future subsidence. These studies are supported by theoretical and experimental research in Shell since the 1950’s concerning reservoir compaction and related surface subsidence. To monitor reservoir compaction and surface subsidence on a regular basis, an extensive monitoring program was set up by NAM. The program comprises leveling surveys, GPS measurements, measurements of shallow formation compaction and in-situ reservoir compaction.

In Groningen weak earthquakes have occurred since 1991 at irregular intervals. A multidisciplinary study from 1991–1993 on the relationship between gas production and earthquakes in the northern part of the Netherlands, combined with further studies concluded, that under certain circumstances these earthquakes may result from gas production. Monitoring is carried out through a seismic observation network with borehole sensors and locally installed accelerometers.

Because of the expected impact of subsidence induced by gas production on surface water management, an Agreement was concluded between the Province of Groningen and NAM.

In line with the 1983 Agreement the ‘Commissie Bodemdaling’ was founded, in which both NAM and the Province of Groningen are represented. On the basis of NAM predictions and actual measurements this Committee determines, what measures are to be taken to prevent, minimize or to correct for effects of gas production induced surface subsidence.

From the 8th/9th centuries onwards the former peat land area in the northwestern part of the Netherlands was drained and reclaimed. Drainage, peat digging and marine erosion of peat deposits created an extension of shallow marine habitats into which Zostera marina (Eel-grass) expanded. Modern publications do not note the use of Eel-grass as starting material for salt-making. Archaeological evidence, however, indicates salt-making activities by using Zostera in medieval times. We postulate that, after salt-containing peat had become difficult to obtain, Eel-grass was used for salt production.

The utilisation of geothermal energy in the Netherlands is primarily focused on deep sedimentary aquifers, which are often intersected by major faults. Geothermal operations (i.e. fluid production and injection) may alter the effective stress state along these faults and trigger induced seismic events. Pore pressure perturbations have been generally considered the main driver of injection-induced seismicity. However, thermal stresses caused by temperature gradients between the re-injected cold fluid and the reservoir rock may also contribute to the triggering of earthquakes in geothermal reservoirs. While existing geothermal power plants operating in sandstone reservoirs did not produce any major induced seismicity, it is a matter of debate whether a reduction in the temperature of the re-injected fluid could increase the seismic hazard potential. In this study, we applied modified Gutenberg–Richter statistics based on frictional Coulomb stress variations implemented in a coupled thermo-hydro-mechanical model to estimate the seismic hazard caused by the operation of a geothermal doublet. We conducted a systematic parametric study to assess and rank the impact of different intrinsic (geological) and extrinsic (operational) parameters on the induced seismic hazard potential. We identified a competing mechanism between induced variations in pore pressure and thermal stress within the reservoir in controlling induced seismicity. We found that stress changes induced by pore pressure variations are the main cause of seismic hazard, although thermally induced stresses also contribute significantly. The results indicate that by optimising the operational parameters it is possible to increase production efficiency while maintaining a long-term control over the fluid injection-induced seismicity.

The largest differentiation event in Earth and other terrestrial planets was the high-pressure, high-temperature process of metal core segregation from a silicate mantle. The abundant element silicon (Si) can be partially sequestered into the metallic core during metal–silicate differentiation, depending on pressure, temperature and planetary oxidation state. Knowledge of the Si content of a planet's core can constrain the conditions of core formation, but in the absence of direct samples from planetary cores, quantifying core Si content is challenging. One relatively new tool to study core formation in terrestrial planets is based on combining measurements of the Si stable isotopic composition of planetary crust and mantle samples with measurements of the Si stable isotope fractionation between metal and silicate at high-temperature and high-pressure conditions. In this study we present the results of a small set of high-pressure, high-temperature (HPT) experiments and combine these with a review of literature data to investigate how the Si isotope fractionation behaviour between metal and silicate varies as a function specifically of experimental run time and temperature. We show that although there is no debate about the sign of fractionation, absolute values for Si isotope fractionation between metal and silicate are difficult to constrain because the experimental database remains incomplete, and because Si isotopic measurements of metals in particular suffer from the absence of a true inter-laboratory comparison. We conclude that in order to derive accurate quantitative estimates of the Si content of the core of the Earth or other planets a wide range of additional experiments will be required.

The Central Graben is a Mesozoic sedimentary basin that is significantly influenced by rift and salt tectonics. Its southern part is located in the German and Dutch sectors of the North Sea. Even though studies exist on the tectonic and stratigraphic development of the Danish and Dutch Central Graben, the German Central Graben as an important link is less investigated. We aim to fill this gap and to investigate the sedimentary development from the Latest Triassic to the Early Cretaceous, the relative influence of salt and rift tectonics on subsidence and how our results fit into the existing studies of the Danish and Dutch Central Graben. Knowledge of the development of the graben and its sedimentation is critical for any possible economic use like hydrocarbon exploitation or carbon capture and storage. Therefore, we mapped nine laterally traceable horizons on 2D and 3D reflection seismic data from the Lower Jurassic to the Lower Cretaceous within the German Central Graben and adjacent Danish Salt Dome Province as well as the northern Dutch Central Graben. These horizons include the base horizons of four tectonostratigraphic mega-sequences of the southern Central Graben adopted from the current Dutch tectonostratigraphic concept. Based on the mapping results, we constructed subsidence, thickness and erosion maps of the tectonostratigraphic mega-sequences and their subdivisions. The tectonostratigraphic mega-sequences were then correlated with well logs to determine the lithology. The results show that the structural and stratigraphic architecture of the German Central Graben was consecutively dominated by either subsidence controlled by rifting, salt tectonics or by thermal uplift and subsidence. We suggest that the German Central Graben is divided by a large strike-slip fault zone, the Mid Central Graben Transverse Zone, into a northern part that geologically rather belongs to the Danish and a southern part that rather belongs to the Dutch Central Graben. We discuss how this division and the tectonics influenced the regional lithology.

In the Eocene to Oligocene transitional strata in Belgium, clay mineral associations vary in response to the climatic evolution and to tectonic pulses. Decreasing smectite to illite ratios and the systematic occurrence of illite-smectite irregular interlayers are consequences of a cooling climate. A marked increase in kaolinite content occurs just after a major unconformity formed at the Bartonian/Priabonian boundary and consequently is interpreted as resulting from the breakdown of uplifted saprolites.

We report a marine Middle Pleistocene mollusc fauna from a borehole near Luxwoude (Friesland, northern Netherlands). The fauna contains several species, including Bittium species, Acanthocardia paucicostata and Polititapes senescens, that hitherto have been used as indicative for warm (lusitanian) conditions in the southern North Sea Basin during the Late Pleistocene Eemian (MIS5e) interglacial. However, the stratigraphic context of the Luxwoude marine fauna indicates a MIS11 or older age for this new fauna. This thermophilous fauna demonstrates very warm-temperate conditions and probably an open marine connection through the Dover Strait towards the south, during this Middle Pleistocene interglacial. In the North Sea basin, this distinctive lusitanian fauna with Bittium-dominated assemblages can therefore no longer be presumed to be of Eemian age without additional evidence.

The artefact size of the Early Middle Palaeolithic (EMP) assemblages in ice-pushed Rhine–Meuse deposits in the central Netherlands decreases northwestward. This trend correlates to the downstream fining direction of the Rhine–Meuse fluvial system, the source of the rock material, showing that locally available material was used. Furthermore, also in line with the fluvial trend, the gravel and cobble trends indicate that EMP artefacts could be present in the buried part of the ice-pushed ridges in the northern part of the central Netherlands (southwest Flevoland). Based on the gravel and cobble data, combined with the literature study, we argue that the artefacts date to marine isotope stages (MIS) 7–6. The review of published data shows that during the time of deposition of the artefact-bearing layer (early MIS 6), the Rhine–Meuse study area was part of a braidplain located in a slightly incised valley. To the north a polar desert was present.

A single internal mould of the holasterid echinoid Holaster laevis (Brongniart, 1822) constitutes the first record of this species from the upper portion (‘Upper Holland Marl’) of the Holland Formation (Rijnland Group), of middle-late Albian age, in the Winterswijk area (eastern Netherlands). The geographic range of H. laevis can thus be extended to this part of western Europe, with previous records from southern England (Wiltshire, Devon) and the Département Ain in east-central France.

Recently drilled geothermal boreholes in Mol, northern Belgium, provide new information on the Lower Carboniferous carbonates in the Campine–Brabant Basin. Because of low primary porosity, fractures in these limestones and dolostones are of major importance for reservoir permeability. The Fullbore Formation MicroImager (FMI) log of the MOL-GT-01 borehole enabled interpretation of bed boundaries and fractures in the subsurface. Relationships between the frequency of these fractures and bed thickness, lithology variations and the presence of faults were explored. The results show that thick beds contain relatively few fractures and thin beds relatively many. Except for lower values in shaly intervals, the fracture frequency (number per metre) is largely independent of lithology. Zones with substantial changes in the structural dip (called a cusp) and/or azimuth of bed boundaries were identified. The clearest cusp is present at a depth of 3284 m. Since the presence of a normal fault is most likely regarding the local and regional geology, this cusp likely resembles a fault-tip fold of a WSW-ward dipping normal fault with an inclination of at least 54°. It is uncertain whether the borehole crossed the fault itself or only a monocline on top of it. Fracture frequency is increased in the vicinity of the interpreted possible faults. Up to a vertical distance of c.45 m from the faults, the mean fracture frequency is higher than in a non-faulted zone with similar lithology. However, frequency differences between these faulted and non-faulted zones are mostly insignificant, so no clear damage zones are present.

Three specimens of the large-sized Eocene campanilid gastropod genus Campanile have been dredged from the modern sea floor in the Bruine Bank area (North Sea, Dutch sector). The material is identified here as Campanile parisiense rarinodosum, a subspecies hitherto unknown from the North Sea Basin. All three shells are strongly abraded, reflecting their secondary derivation. The new finds suggest that fossiliferous strata of probably late Lutetian (middle Eocene) age are represented in the southern North Sea Basin, situated most likely in the southeastern part of the UK sector. The present material of Campanile must have been reworked into the Dutch sector via Quaternary rivers. The occurrence of Campanile parisiense rarinodosum would indicate close biogeographic ties between the North Sea and the western French Atlantic basins during the late Lutetian. These new records thus shed light on the palaeogeography of the area during two widely separated geological time slices.

Gas Field Planning Tool (GFPT) was developed in 1990 by the Shell Group of Companies to fill the need for a tool for gas field planning and development using deterministic subsurface and surface models. Main initiators were Shell Canada, NAM (the Netherlands), Shell Expro (UK) and BSP (Shell Brunei), as these companies are major gas producers.

Shell Companies now have several years experience with using the GFPT. Application ranges from simple single field models to corporate-level models with a large number of gas reservoirs and wells. Shell companies now using GFPT models are Shell Expro (UK), BSP (Brunei), SSB (Malaysia), Shell Canada, SPDC (Nigeria), SDA (Australia), Woodside (Australia), PDO (Oman), NAM (the Netherlands), New Business Development (e.g. Lunar Project) and in future also Shell Egypt.

NAM currently has a GFPT model for the Anjum field in Friesland and for the Ten Arlo field in the north of Holland.

GFPT is currently being migrated to an HFPT (Hydrocarbon Field Planning Tool), which can also be used for planning of condensate, oil and water developments and for control of hydrocarbon compositions in the network using PVT de-lumping at the well head (e.g. for LNG plants) and optimisation techniques (linear, non-linear or based on bean-back lists).

In the above mentioned article (Janssen et al., 2011) the caption of Figure 1 was not complete and missed a reference citation.

The Late Cretaceous was a time of blossoming teleost diversification that came to a sudden restriction and partial termination during the extinction event at the Cretaceous–Paleogene (K/Pg) boundary. Among the dominant and diverse Late Cretaceous teleost groups prior to the K/Pg boundary event were certain pelagic Aulopiformes (e.g., Ichthyotringoidei and Enchodontoidei) and a large variety of basal Acanthomorpha whose relationships are difficult to determine. The skeletal record diminishes during the late Campanian and is low in the Maastrichtian and Paleocene, constituting the so-called ‘Patterson’s Gap’. Recent studies of fossil otoliths, however, have significantly increased the number of taxa recognised for this time inerval, but most of the putative extinct forms lack adequate calibration with otoliths found in situ in articulated skeletons. However, the otolith assemblages do confirm the presence of great morphological diversity among Aulopiformes and Acanthomorpha incertae sedis that became extinct at the K/Pg boundary. In the present review, we elucidate the effect of the K/Pg boundary from an otolith perspective and categorise extinct lineages and survivors. It is interesting to recognise that several of the surviving lineages are represented by groups that probably originated during the Late Cretaceous but were not particularly common up to the K/Pg boundary and began to expand rapidly and diversify during the early Paleogene. Such lineages probably took advantage to populate void ecospace that may have opened following the extirpation of previously dominant lineages. During the early Paleogene, the otolith record shows that the Ophidiiformes and perciforms s. lat. were the ones that diversified the most rapidly and became the most abundant, and in certain areas associated with the Gadiformes.

The risk of five pesticides (atrazine, simazine, bentazone, mecoprop and MCPA) contaminating a Quaternary phreatic aquifer (the water supply area of Sint-Jansteen, the Netherlands) is assessed based on laboratory experiments and solute transport modelling (MODFLOW-MT3D). Batch experiments either show long half-lives (at least 1500 days) or no degradation at all for bentazone, atrazine and simazine while mecoprop and especially MCPA degrade much faster (half-lives down to 4.1 days). Column experiments show significant sorption to the aquifer sediment only for atrazine and simazine under certain circumstances. A series of experiments were conducted during which the type of the sediment, the grain size, the content of the organic matter and the acidity of the groundwater were varied. These experimental results were subsequently incorporated in a solute transport model for the aquifer resulting in the following ranking of the contamination risk for the selected pesticides (from low to high): MCPA, mecoprop, simazine, atrazine, bentazone. This ranking was confirmed by observed pesticide concentrations in samples taken from piezometers and extraction wells from the aquifer.

A bifacially worked flint tool has recently been found on the North Sea beach of Ameland, one of the Wadden Islands in the northern Netherlands. It probably dates from the Middle Palaeolithic because its surface modifications include windgloss which in this area originated especially during the Weichselian Late Pleniglacial. The tool was probably first worked by a skilled knapper and subsequently, after a break occurred, by an apprentice. It is suggested that the tool was transported to Ameland from the North Sea bottom in the course of sand replenishment activities. Other artefacts from the Wadden Islands allegedly left by Neanderthals are also briefly discussed.