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Enhanced weathering of olivine has been suggested as a measure to lower the atmospheric CO2 level and it might also mitigate ocean acidification. This study aimed to characterise how olivine can weather in seawater, to elucidate the role of secondary precipitation and to ascertain the efficiency in terms of molar CO2 removal per mole of olivine dissolution. Geochemical thermodynamic equilibrium modelling was used, which considered both the variable mineralogical composition of olivine and the kinds of secondary precipitates that may be formed. The advantage is that such an approach is independent from local or regional factors as temperature, related kinetics, mineralogy, etc. The results show that the efficiency falls when secondary precipitates are formed. When Fe-bearing olivine undergoes weathering in an oxic environment, Fe(III) hydroxides will inevitably be formed, and as a result of this acidifying process, CO2 could be released to the atmosphere. This might also enhance ocean acidification when Fe-rich olivine becomes used. Ocean alkalinisation only happens when more than 1 mol/kgH2O Mg-rich olivine weathers. Maintenance of supersaturation for calcite or aragonite as holds in seawater reduces the efficiency by about a factor of two compared to the efficiency without secondary precipitation. Precipitation of sepiolite as Mg silicate reduces the efficiency even more. Magnesite precipitation has a similar effect to Ca carbonate precipitation, but according to the literature magnesite precipitation is improbable at ambient conditions and relatively low supersaturation. When less than 0.05 mmol olivine/kg(seawater) weathers the efficiency is slightly different than at higher intensities, due to strong buffering by seawater alkalinity. © 2016 The Author

The crustal seismic velocity structure of northwestern Europe shows a low P-wave velocity zone (LVZ) in the lower crust along the Caledonian Thor suture zone (TSZ) that cannot be easily attributed to Avalonia or Baltica plates abutting the TSZ. The LVZ appears to correspond to a hitherto unrecognized crustal segment (accretionary complex) that separates Avalonia from Baltica, explaining well the absence of Avalonia further east. Consequently, the northern boundary of Avalonia is shifted ~150 km southward. Our interpretation, based on analysis of deep seismic profiles, places the LVZ in a consistent crustal domain interpretation. A comparison with present-day examples of the Kuril and Cascadia subduction zones suggests that the LVZ separating Avalonia from Baltica is composed of remnants of the Caledonian accretionary complex. If so, the present-day geometry probably originates from pre-Variscan extension and eduction during Devonian-Carboniferous backarc extension. The reinterpretation of deep crustal zonation provides a crustal framework in which the northern limit of Avalonia corresponds to the southern limit of the deep North German Basin and the northern limit of prolific gas reservoirs and late Mesozoic inversion structures. © 2016 Geological Society of America.

The Uddelermeer is a unique lake for The Netherlands, containing a sediment record that continuously registered environmental and climatic change from the late Pleistocene on to the present. A 15.6-m-long sediment record was retrieved from the deepest part of the sedimentary basin and an age–depth model was developed using radiocarbon dating, 210Pb dating, and Bayesian modeling. Lake-level change was reconstructed using a novel combination of high-resolution palaeoecological proxies (e.g. pollen, non-pollen palynomorphs, chironomids), quantitative determinations of lake-level change (ground-penetrating radar), and estimates of changes in precipitation (lipid biomarker stable isotopes). We conclude that lake levels were at least as high as present-day water levels from the late glacial to 3150 cal. yr BP, with the exception of at least one lake-level lowstand during the Preboreal period. Lake levels were ca. 2.5 m lower than at present between 3150 and 2800 cal. yr BP, which might have been the result of a change in moisture source region prior to the so-called 2.8-kyr event. Increasing precipitation amounts around 2800 cal. yr BP resulted in a lake-level rise of about 3.5–4 m to levels that were 1–1.5 m higher than at present, in line with increased precipitation levels as inferred for the 2.8-kyr event from nearby raised bog areas as well as with reconstructions of higher lake levels in the French Alps, all of which have been previously attributed to a phase of decreased solar activity. Lake levels decreased to their present level only during recent times, although the exact timing of the drop in lake levels is unclear.

Upper Rotliegend sediments of Permian age from the northeast Netherlands show moderate to good reservoir

The Rupelian clay in the Netherlands is currently the subject of a feasibility study with respect to the storage of radioactive waste in the Netherlands (OPERA-project). Many features need to be considered in the assessment of the long-term evolution of the natural environment surrounding a geological waste disposal facility. One of these is permafrost development as it may have an impact on various components of the disposal system, including the natural environment (hydrogeology), the natural barrier (clay) and the engineered barrier. Determining how deep permafrost might develop in the future is desirable in order to properly address the possible impact on the various components. It is expected that periglacial conditions will reappear at some point during the next several hundred thousands of years, a typical time frame considered in geological waste disposal feasibility studies. In this study, the Weichselian glaciation is used as an analogue for future permafrost development. Permafrost depth modelling using a best estimate temperature curve of the Weichselian indicates that permafrost would reach depths between 155 and 195 m. Without imposing a climatic gradient over the country, deepest permafrost is expected in the south due to the lower geothermal heat flux and higher average sand content of the post-Rupelian overburden. Accounting for various sources of uncertainty, such as type and impact of vegetation, snow cover, surface temperature gradients across the country, possible errors in palaeoclimate reconstructions, porosity, lithology and geothermal heat flux, stochastic calculations point out that permafrost depth during the coldest stages of a glacial cycle such as the Weichselian, for any location in the Netherlands, would be 130–210 m at the 2σ level. In any case, permafrost would not reach depths greater than 270 m. The most sensitive parameters in permafrost development are the mean annual air temperatures and porosity, while the geothermal heat flux is the crucial parameter in permafrost degradation once temperatures start rising again.

The Southern part of the Flevopolder has shown considerable subsidence since its reclamation in 1967. We have set up an integrated method to use subsidence data, water level data and forward models for compaction, oxidation and the resulting subsidence to estimate the driving parameters. Our procedure, an Ensemble Smoother with Multiple Data Assimilation, is very fast and gives insight into the variability of the estimated parameters and the correlations between them. We used two forward models: the Koppejan model and the Bjerrum model. In first instance, the Bjerrum model seems to perform better than the Koppejan model. This must, however, be corroborated with more elaborate parameter estimation exercises in which in particular the water level development is taken into account.

We present an interpolation model that describes Holocene groundwater level rise and the creation of accommodation space in 3D in the Rhine-Meuse delta – the Netherlands. The model area (ca. 12 400 km2) covers two palaeovalleys of Late Pleistocene age (each 30 km wide) and the overlying Holocene deposits of the Rhine-Meuse delta, the Holland coastal plain, and the Zuiderzee former lagoon. Water table rise is modelled from 10 800 to 1000 cal. BP, making use of age-depth relations based on 384 basal peat index points, and producing output in the form of stacked palaeo groundwater surfaces, groundwater age-depth curves, and voxel sets. These products allow to resolve (i) regional change and variations of inland water table slopes, (ii) spatial differences in the timing and pacing of transgression, and (iii) analysis of interplay of coastal, fluvial and subsidence controls on the provision of accommodation space. The interpolation model is a multi-parameter trend function, to which a 3D-kriging procedure of the residuals is added. This split design deploys a generic approach for modelling provision of accommodation space in deltas and coastal lowlands, aiming to work both in areas of intermediate data availability and in the most data-rich environments. Major provision of accommodation space occurred from 8500 cal BP onwards, but a different evolution occurred in each of the two palaeovalleys. In the northern valley, creation of accommodation space began to stall at 7500 cal BP, while in the southern valley provision of new accommodation space in considerable quantities continued longer. The latter is due to the floodplain gradient that was maintained by the Rhine, which distinguishes the fluvial deltaic environment from the rest of the back-barrier coastal plain. The interpolation results allow advanced mapping and investigation of apparent spatial differences in Holocene aggradation in larger coastal sedimentary systems. Furthermore, they provide a means to generate first-order age information with centennial precision for 3D geological subsurface models of Holocene deltas and valley fills. As such, the interpolation is of use in studies into past and present land subsidence and into low land sedimentation.

Multidisciplinary analysis including paleomagnetic, sedimentologic, sea-level change, luminescence dating and palynologic research was performed on a 25m long orientated core taken at Rutten, close to Eemian key localities in the Netherlands. The main goal of our research was to test a possible delayed onset of temperate conditions in this region compared to Southern Europe, occurring within the Last Interglacial. The sediments revealed the presence of the paleomagnetic Blake Event in ca. 10m of lower-deltaic floodbasin sediments that contain a pollen record covering the Eemian. The position of the Blake Event in relation to the pollen stratigraphy concurs with the earlier studied Neumark Nord 2 site. Paleomagnetic correlation to core MD95-2042 off SW Iberia indicates ca. 5kyr diachroneity between the pollen-based onset of temperate interglacial conditions between northern and southern Europe. The onset of the Eemian in north-western and central Europe (ca. 121.0ka) post-dates the Marine Isotope Stage 6/5e transition by ca. 10kyr. In addition, the Rutten data provide evidence for a relatively long duration of the Blake Event of at least 8kyr. The late onset of the temperate conditions that define the base of the Eemian, imply that NW Europe with the Eemian type area is not the most suited region to define the beginning of the Last Interglacial and Late Pleistocene for global chronostratigraphic use. © 2015 Elsevier B.V.

This paper presents a new perspective for the temporal variation of crop cultivation adoption during the period 6000-5400BP in Flevoland (central Netherlands) based on the spatial evolution of soils and hydrology. To determine the role of soil properties and groundwater level rise in the adoption of crop cultivation in wetlands, mapping of the mid-Holocene palaeotopography, palaeohydrology, soil conditions and distribution of Swifterbant archaeological remains was combined with grain size analyses of cored sediments in two selected study areas. Results show that the low natural fertility and water holding capacity of the sandy soils on the Pleistocene surface in southern Flevoland compared to the loamy soils in the northern part of Flevoland, can explain the lack of crop cultivation in the south. The relation between natural soil fertility and initial adoption of crop cultivation in the IJssel/Vecht valley corresponds with examples from other wetlands in northwest Europe. © 2014 Elsevier Ltd and INQUA.

The Gravity field and steady-state Ocean Circulation Explorer (GOCE) is the European Space Agency's (ESA)satellite gravity mission to determine the Earth's mean gravity field. GOCE delivers gravity gradients, anew type of satellite data. We study how these data can improve modeling of the Earth's lithosphere. We discuss the use of the original GOCE gravity gradients versus the use of gravity gradients in grids at satellite altitude or close the Earth's surface and conclude that grids are easier to handle than the original data because one does not have to deal with very different error characteristics of the different gradients, given in a rotating frame at varying heights. The downward continuation to the surface enhances signaland better reflects the near-surface geology. But this does not outweigh the amplification of noise and omission errors, which is why we recommend using the field at mean satellite altitude for lithospheric modeling. The North-East Atlantic region is ideal to analyze the additional value of GOCE gravity gradients because it is a well-studied region in terms of regional geophysics. We calculated the gradient sensitivity for crustal depth slices using a 3D lithospheric model. This reveals that especially interfaces with large density contrasts have a distinct signal in the gravity gradients, but that they are quite insensitive to intra-crustal density sources, which can have quite a large effect on surface gravity data. We also show thatthe satellite gradients have a depth sensitivity well suited to study the upper mantle density structure, making them complementary to gravity and seismic tomography. In the underexplored Rub'al-Khaliarea the GOCE vertical gradient was used to invert for crustal thickness. The updated Moho model givesa good fit to four of the six gradients and independent depths from seismic stations. The Moho modelwas used to update the heat flow model and source rock maturity maps, which are generally consistent with known source rock maturity trends in the surrounding regions. GOCE gradients are therefore usefulto map crustal thickness and deep regional structures for frontier areas. In combination with other data, heat flow can be modeled which is essential for basin maturity evaluation. © 2013 Elsevier B.V.

Aggregate resource assessments, derived from three subsequent generations of voxel models, were compared in a qualitative way to illustrate and discuss modelling progress. We compared the models in terms of both methodology and usability. All three models were produced by the Geological Survey of the Netherlands. Aggregate is granular mineral material used in building and construction, and in this case consists of sand and gravel. On each occasion ever-increasing computer power allowed us to model at a higher resolution and use more geological information to constrain interpolations. The two oldest models, built in 2005 and 2007, were created specifically for aggregate resource assessments, the first as proof of concept, the second for an online resource information system. The third model was derived from the ongoing multipurpose systematic 3D modelling programme GeoTOP. We used a study area of 40 × 40 km located in the central Netherlands, which encompasses a section of the Rhine-Meuse delta and adjacent glacial terrains to the north. Aggregate resource assessments rely on the extent to which the occurrence and grain size of sand and gravel are resolved, and on proper representation of clay and peat layers (overburden and intercalations) that affect exploitability. Average model properties (e.g. total aggregate content) are about the same in all three models, except for a difference resulting from converting older lithological classifications to the current one. This difference illustrates that data selection and preparation are paramount, especially when dealing with quality issues. Generally speaking the results of the aggregate resource assessments are consistent and satisfactory for all three models, provided that they are judged at the appropriate scale. However, the assessments based on GeoTOP best approach the desired scale of use for the aggregates industry; in that sense progress was significant and each model was a better fit for the purpose. © 2015 Netherlands Journal of Geosciences Foundation.

by Witold Zuchiewicz and Jerzy Zasadni (2012) intended for this volume YOUNG TECTONICS OF THE OUTER WESTERN CARPATHIANS IN THE LIGHT OF SOME MORPHOMETRIC INDICES In this paper, we test the applicability of some morphometric indices commonly used in tectonic-geomorphological studies to the area of the Outer Western Carpathians representing an Alpine fold-and-thrust belt. This belt was shaped largely in Miocene times and shows traces of Pliocene-Quaternary tectonic activity consisting mainly in some remnant folding and faulting. This is indicated by scarce examples of faulting within Quaternary strata, numerous cases of clast fracturing owing to palaeoearthquakes of relatively large magnitudes, as well as warping and tilting of Pleistocene and Holocene strath terraces. Analysis of selected morphometric indices (valley floor width-valley height ratio, riverbed gradients, stream length-gradient index, basin elongation ratios and others), conducted for the entire region and some chosen test areas in the westernmost part of the Outer Western AC C EP TE D M AN U SC R IP T ACCEPTED MANUSCRIPT 24 Carpathians, proved their usefulness in detecting zones showing tendencies to young surface uplift. However, in the case of the stream length-gradient index (SL, Hack’s index) a word of caution should be added, since the index is extremely sensitive to lithologic contrasts in the bedrock and its applicability to young tectonic analysis of fold-and-thrust belts appears to be strongly limited. Dr Andrzej Piotrowski, apiot@pgi.gov.pl, Szczecinie Panstwowy Instytut Geologiczny, Szczecin, Poland and Dr Klaus Reicherter, RWTH Aachen University, Germany

The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10−810−8–View the MathML source10−4 ms−1) or in the high velocity regime (0.01–1 m s−1). Here, we report on the evolution of friction and corresponding operating deformation mechanisms in analog gouges deformed from low to high slip rates, bridging the gap between these low and high velocity regimes. We used halite and halite–muscovite gouges to simulate processes, governing friction, active in upper crustal quartzitic fault rocks, at conditions accessible in the laboratory. The gouges were deformed over a 7 orders of magnitude range of slip rate (10−710−7–1 m s−1) using a low-to-high velocity rotary shear apparatus, using a normal stress of 5 MPa and room-dry humidity. Microstructural analysis was conducted to study the deformation mechanisms. Four frictional regimes as a function of slip rate could be recognized from the mechanical data, showing a transitional regime and stable sliding (10−710−7–10−6 m s−1), unstable sliding and weakening (10−610−6–10−3 m s−1), hardening (10−210−2–10−1 m s−1) and strong weakening (10−110−1–1 m s−1). Each of the four regimes can be associated with a distinct microstructure, reflecting a transition from mainly brittle deformation accompanied by pressure solution healing to temperature activated deformation mechanisms. Additionally, the frictional response of a sliding gouge to a sudden acceleration of slip rate to seismic velocities was investigated. These showed an initial strengthening, the amount of which depended on the friction level at which the step was made, followed by strong slip weakening.

The Permian Rotliegend Slochteren Formation is a prolific gas bearing interval in the Netherlands. However, their reservoir porosity and permeability can be locally severely degraded by diagenetic pore-blocking cements. This work focusses on the cementational control on the reservoir quality. The drivers and causes of cementation and its effect on the reservoir quality were studied by integrated analysis of petrography, basin modelling, fluid flow systematics, sedimentology and geochemistry. Results indicate that cementation is both environmentally and structurally controlled with superimposed influence of Rotliegend meteoric, Zechstein and Carboniferous fluids. Although mineral authigenesis and reservoir quality have locally different principal drivers, the projection of regional models onto the whole of the Dutch Upper Rotliegend can improve the prediction of authigenesis at yet unexplored locations.

Non-hydrocarbons (H2S, CO2, N2) reduce the economic value of natural gas accumulations. This paper presents new approaches to evaluate the probability to encounter high amounts of non-hydrocarbons. These approaches were developed as one of the deliverables of a 2-year JIP project carried out by TNO from September 2014-July 2016. The newly compiled quality-coded database of geochemical and stable isotopic compositions of natural gas accumulations in the onshore and offshore Netherlands, the visualization of these data in maps and the analysis and interpretation of the identified spatial distribution of the geochemical and isotopic composition of the gas provided improved process-based insight into the spatial distribution of the non-hydrocarbons in relation to its geological setting. This insight allowed the identification of factors to evaluate the probability of encountering high amounts of non-hydrocarbons. The development and application of the approach is illustrated for case study examples of CO2-rich gases in the Netherlands onshore and offshore.

The Permian Rotliegend Slochteren Formation is a prolific gas bearing interval in the Netherlands. However, their reservoir porosity and permeability can be locally severely degraded by diagenetic pore-blocking cements. This work focusses on the cementational control on the reservoir quality. The drivers and causes of cementation and its effect on the reservoir quality were studied by integrated analysis of petrography, basin modelling, fluid flow systematics, sedimentology and geochemistry. Results indicate that cementation is both environmentally and structurally controlled with superimposed influence of Rotliegend meteoric, Zechstein and Carboniferous fluids. Although mineral authigenesis and reservoir quality have locally different principal drivers, the projection of regional models onto the whole of the Dutch Upper Rotliegend can improve the prediction of authigenesis at yet unexplored locations.

We develop a framework based on the lexicographic method and the newly developed Stochastic-Simplex-Approximate-Gradient (StoSAG) algorithm to maximize the expected net-present-value (NPV) and minimize the associated risk or uncertainty in robust life-cycle production optimization. With the lexicographic method, we first maximize the expectation of the life-cycle NPV value, then we minimize the risk using the resulting optimal value of expected NPV as a constraint. This constrained optimization problem is solved with the augmented Lagrangian method. The measures of risk considered include the standard deviation, the worst-case scenario (minimum NPV over the set of realizations) and conditional-value-at-risk (CVaR). Results obtained with different risk measures are benchmarked using two reservoir examples, namely, a channelized reservoir model and the well-known Brugge reservoir model in order to determine the effect of the choice of the risk measure. In addition, the performance of the one-step (unconstrained) CVaR is compared with that of the two-step CVaR (lexicographic-based CVaR). © 2017 Elsevier B.V.

The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10−8–10−4 ms−1) or in the high velocity regime (0.01–1 m s−1). Here, we report on the evolution of friction and corresponding operating deformation mechanisms in analog gouges deformed from low to high slip rates, bridging the gap between these low and high velocity regimes. We used halite and halite–muscovite gouges to simulate processes, governing friction, active in upper crustal quartzitic fault rocks, at conditions accessible in the laboratory. The gouges were deformed over a 7 orders of magnitude range of slip rate (10−7–1 m s−1) using a low-to-high velocity rotary shear apparatus, using a normal stress of 5 MPa and room-dry humidity. Microstructural analysis was conducted to study the deformation mechanisms. Four frictional regimes as a function of slip rate could be recognized from the mechanical data, showing a transitional regime and stable sliding (10−7–10−6 m s−1), unstable sliding and weakening (10−6–10−3 m s−1), hardening (10−2–10−1 m s−1) and strong weakening (10−1–1 m s−1). Each of the four regimes can be associated with a distinct microstructure, reflecting a transition from mainly brittle deformation accompanied by pressure solution healing to temperature activated deformation mechanisms. Additionally, the frictional response of a sliding gouge to a sudden acceleration of slip rate to seismic velocities was investigated. These showed an initial strengthening, the amount of which depended on the friction level at which the step was made, followed by strong slip weakening. © 2016 Elsevier B.V.

We develop a framework based on the lexicographic method and the newly developed Stochastic-Simplex-Approximate-Gradient (StoSAG) algorithm to maximize the expected net-present-value (NPV) and minimize the associated risk or uncertainty in robust life-cycle production optimization. With the lexicographic method, we first maximize the expectation of the life-cycle NPV value, then we minimize the risk using the resulting optimal value of expected NPV as a constraint. This constrained optimization problem is solved with the augmented Lagrangian method. The measures of risk considered include the standard deviation, the worst-case scenario (minimum NPV over the set of realizations) and conditional-value-at-risk (CVaR). Results obtained with different risk measures are benchmarked using two reservoir examples, namely, a channelized reservoir model and the well-known Brugge reservoir model in order to determine the effect of the choice of the risk measure. In addition, the performance of the one-step (unconstrained) CVaR is compared with that of the two-step CVaR (lexicographic-based CVaR). © 2017 Elsevier B.V.

Non-hydrocarbons (H2S, CO2, N2) reduce the economic value of natural gas accumulations. This paper presents new approaches to evaluate the probability to encounter high amounts of non-hydrocarbons. These approaches were developed as one of the deliverables of a 2-year JIP project carried out by TNO from September 2014-July 2016. The newly compiled quality-coded database of geochemical and stable isotopic compositions of natural gas accumulations in the onshore and offshore Netherlands, the visualization of these data in maps and the analysis and interpretation of the identified spatial distribution of the geochemical and isotopic composition of the gas provided improved process-based insight into the spatial distribution of the non-hydrocarbons in relation to its geological setting. This insight allowed the identification of factors to evaluate the probability of encountering high amounts of non-hydrocarbons. The development and application of the approach is illustrated for case study examples of CO2-rich gases in the Netherlands onshore and offshore.

ICDP workshop COring the NOrth Sea Cenozoic focused on the scientific objectives and the technical aspects of drilling and sampling. Some 55 participants attended the meeting, ranging from climate scientists, drilling engineers, and geophysicists to stratigraphers and public outreach experts. Discussion on the proposed research sharpened the main research lines and led to working groups and the necessary technical details to compile a full proposal that was submitted in January 2016.

One of the main activities in the (re-)development of large hydrocarbon fields is the drilling of new wells. The drilling process may involve a large number of wells and take several years to complete. Challenges include the selection of a limited set of wells from many possible well paths, and the scheduling of the drilling itself. Complications may arise from constraints imposed by platform availability and processing capacity, and from differences in the complexity of well paths that influence cost, time and risk. Several strategies are investigated to find an optimal drilling sequence in the presence of uncertainty. An ensemble-based robust optimization method is employed to maximize the expected value of an economical objective. Parameterizations of the drilling sequence in terms of both priority and time controls are considered. While these controls are continuous, the associated objective function is piece-wise constant, which poses challenges for gradient-based optimization schemes, including those based on perturbation approaches. The impact of optimizer, perturbation sampling scheme, and of control type and mapping are determined. Results show that approaches based on priority controls can deliver significant improvements of the well drilling sequence. Perturbation schemes leading to initially severe but reduced re-ordering later on are recommended. DCSE; Schlumberger; Shell

Classic geological reservoir characterisation relies on interpolation of high resolution well data with (at best) low resolution seismic derived data. In order to fill the data gap (e.g. in labyrinthine type fluvial deposits) we present a methodology to integrate basin scale information in reservoir scale static models by calibrating output from a Stratigraphic Forward Model (SFM). This project showcases the applicability of the integrated workflow to improve facies and property prediction at different scales. By calibrating the parameterized data from the SFM to independent constraints such as thicknesses from seismic interpretations and well logs the model greatly improve property prediction. Previous studies showed the application to synthetic datasets, this study aims to apply the methodology to the Holocene Rhine-Meuse fluvial deposits in the shallow subsurface of the Netherlands. The extraordinary level of detail in the model of these deposits and the parameterized fluvial sedimentation routine in the SFM used provide an ideal test case for the workflow proposed. The ultimate application of the workflow is intended to improve the geological and property models at greater depth where data coverage is limited. © 2016, European Association of Geoscientists and Engineers, EAGE. All rights reserved.

In this study a new approach to geothermal potential assessment was set up and applied in four regions in southern Italy. Our procedure, VIGORThermoGIS, relies on the volume method of assessment and uses a 3D model of the subsurface to integrate thermal, geological and petro-physical data. The method thus produces 2D geothermal potential maps for three different uses: district heating, district heating and cooling, and electrical power production. Our study focused on carbonate reservoirs, which usually present an excellent natural permeability and important geothermal gradients at depth. Our computations were possible thanks to the large quantity of data available from hydrocarbon exploration that largely investigate deep-seated reservoirs. Based on geothermal potential available for power production we estimate the contribution of the geothermal energy in the CO2 emissions reduction in the study regions. Moreover policy makers as well as investors can use our maps to establish new policies and to locate the most promising places for geothermal development, in line with the international low carbon strategy. © 2016 Elsevier Ltd

The Toarcian (Early Jurassic) Posidonia Shale Formation is a possible unconventional gas source in Northern Europe and occurs within the Cleveland Basin (United Kingdom), the Anglo-Paris Basin (France), the Lower Saxony Basin and the Southwest Germany Basin (Germany), and the Roer Valley Graben, the West Netherlands Basin, Broad Fourteens Basin, the Central Netherlands Basin and the Dutch Central Graben in The Netherlands. Outcrops can be found in the United Kingdom and Germany. Since the Posidonia Shale Formation does not outcrop in the Netherlands, sample material suitable for experimental studies is not easily available. Here we have investigated lateral equivalent shale samples from six different locations across Northern Europe (Germany, The Netherlands, The North sea and United Kingdom) to compare the microstructure and composition of Toarcian shales. The objective is to determine how homogeneous or heterogeneous the shale deposits are across the basins, using a combination of Ion Beam polishing, Scanning Electron Microscopy and X-ray diffraction. The work presented here shows that the Toarcian shales of Northern Europe display considerable homogeneity in mineralogy and microstructure in the different investigated samples and formations, where the largest variability is the carbonate content ranging from almost zero up to 80%. We conclude that the outcrop locations in Germany and the United Kingdom are suitable analogues with respect to their mineralogy and microstructure for experimental studies on the Posidonia Shale in the Dutch subsurface. © 2016 The Authors

Recently, a distance parameterization of flood fronts derived from seismic anomalies was proposed as a solution in combination with the ensemble Kalman filter (EnKF), which is known as an efficient method for conditioning of multiple reservoir models to observed data. Even though the distance parameterization in terms of front positions is efficient and effective in reducing both nonlinearity and the effective number of seismic data, which improves the performance of the EnKF, the method adopted for distance computation therein is only applicable for reservoir models with regular Cartesian grids because large errors will be introduced otherwise. In this paper, we improve the applicability of the distance parameterization in terms of front positions by extending the fast marching method for solution of the Eikonal equation to complex simulation grids. This is realized by taking advantage of a diagonal stencil in the fast-marching implementation which allows more accurate calculations of distances between observed and simulated fronts, and by an isoparametric mapping which provides a transformation from the Cartesian to curvilinear coordinates. The improvements of the proposed methods are demonstrated through a number of numerical experiments on corner-point grid including a 3D synthetic case of Norne full-field model. DCSE; Schlumberger; Shell

Geophysical monitoring activities were an important component of the CO2 injection program at the Ketzin site, Germany. Here we report on the seismic and electrical resistivity tomography (ERT) measurements performed during the period of the site development and CO2 injection. Details on the site geology, the history of the CO2 injection operation, and petrophysical models relevant for the interpretation of the geophysical data are presented. The seismic measurements comprise 2D and 3D surface seismic surveys, vertical seismic profilings, and crosshole measurements. Apart from the measurements, results from advanced processing methods, such as impedance inversion and full-waveform inversion are also presented. In addition, results from crosshole ERT and surface-downhole ERT are presented. If operational efforts are taken into consideration we conclude that a combination of several geophysical methods is preferable given the demands of a spatiotemporally comprehensive monitoring program. We base this conclusion on that the different imaging characteristics and petrophysical sensitivities of different methods can complement each other. An important finding is, based on signal quality and reduced operational costs, that the use of permanent installations is promising. Generally, specific monitoring layouts will depend on site-specific characteristics, such as reservoir depth, availability of wells, petrophysical characteristics, and accessibility of surface locations. Given the comprehensive range of methods applied, the reported results are not only relevant to the operation of CO2 storage sites, but are also of interest to other monitoring projects dealing with fluid injection or production. © 2015 Elsevier B.V.

During the Cretaceous greenhouse, episodes of widespread ocean deoxygenation were associated with globally occurring events of black shale deposition. Possibly the most pronounced of these oceanic anoxic events (OAE's) was the Cenomanian-Turonian OAE2 (~94 Ma). However, although certain redox sensitive trace metals tend to be preferentially sequestered in sediments deposited under anoxic conditions, with Mo drawdown being specifically prone to euxinic settings, these elements are generally somewhat depleted in sediments deposited during OAE2. To understand the driving factors responsible for this depleted trace metal drawdown, we have studied a low latitude section from the proto-North Atlantic Ocean (Tarfaya S57), where existing biomarker and iron-sulphur data point to a dominantly euxinic water column, with periodic transitions to ferruginous (Fe-rich) water column conditions. We utilise a variety of redox proxies (Fe-speciation, redox sensitive trace metals and Mo isotopes), which, in combination, allows us to evaluate the detailed nature of ocean redox conditions and hence controls on trace metal drawdown. The results suggest that seawater δ98Mo values may have ranged between ~0.6 and 1.1‰ during OAE2, likely connected to changes in the local Mo reservoir as a consequence of low and probably heterogeneous concentrations of Mo in the ocean. The very low Mo/TOC ratios at Tarfaya and elsewhere in the proto-North Atlantic may support a model in which deep-water circulation was partially restricted within and between the North Atlantic and other ocean basins. We propose that the combination of a low and possibly heterogeneous δ98Mo of seawater Mo, together with low Mo/TOC ratios, points to a large decrease in the global oceanic Mo reservoir during OAE2, reflecting a major global scale increase in Mo drawdown under persistent euxinic conditions. © 2016 Elsevier B.V.

Subsurface CO2 storage has been identified as one of the key methods to reduce the emission of CO2 to the atmosphere. Remediation or mitigation of unwanted migration from potential storage sites requires novel approaches for which feasibility is yet to be demonstrated. This study focuses on a solution to mitigate CO2 migration through naturally occurring faults, using a polymergel to drastically reduce the permeability of the fault. The radius of influence of the polymer injection is extended by using hydraulically stimulated fractures to transport the sealant to the leaking area. Reservoirs eligible for CO2 storage generally exhibit relatively high permeability and consequentially high leak-off of frac fluids. Therefore, the extent of hydraulic fractures is expected to be limited. Faults and fractures may be surrounded by a damaged zone with a permeability that is higher than the reservoir (up to 10 times). Considering the extra permeability of the damaged zone, the surface covered by the sealant may be extended by another 20-40%. Current results shows that this technique is technically feasible (with proper choices of polymer-gel and treatment) to mitigate CO2 leakage through a leaking fault.

This guide provides a major revision and update of the stratigraphy of the Cromer Knoll, Shetland

One of the main activities in the (re-)development of large hydrocarbon fields is the drilling of new wells. The drilling process may involve a large number of wells and take several years to complete. Challenges include the selection of a limited set of wells from many possible well paths, and the scheduling of the drilling itself. Complications may arise from constraints imposed by platform availability and processing capacity, and from differences in the complexity of well paths that influence cost, time and risk. Several strategies are investigated to find an optimal drilling sequence in the presence of uncertainty. An ensemble-based robust optimization method is employed to maximize the expected value of an economical objective. Parameterizations of the drilling sequence in terms of both priority and time controls are considered. While these controls are continuous, the associated objective function is piece-wise constant, which poses challenges for gradient-based optimization schemes, including those based on perturbation approaches. The impact of optimizer, perturbation sampling scheme, and of control type and mapping are determined. Results show that approaches based on priority controls can deliver significant improvements of the well drilling sequence. Perturbation schemes leading to initially severe but reduced re-ordering later on are recommended. DCSE; Schlumberger; Shell

High nitrogen (N) and phosphorus (P) fluxes from upstream agriculture threaten aquatic ecosystems in surface waters and estuaries, especially in areas characterized by high agricultural N and P inputs and densely drained catchments like the Netherlands. Controlled drainage has been recognized as an effective option to optimize soil moisture conditions for agriculture and to reduce unnecessary losses of fresh water and nutrients. This is achieved by introducing control structures with adjustable overflow levels into subsurface tube drain systems. A small-scale (1 ha) field experiment was designed to investigate the hydrological and chemical changes after introducing controlled drainage. Precipitation rates and the response of water tables and drain fluxes were measured in the periods before the introduction of controlled drainage (2007–2008) and after (2009–2011). For the N and P concentration measurements, auto-analyzers for continuous records were combined with passive samplers for time-averaged concentrations at individual drain outlets. The experimental setup enabled the quantification of changes in the water and solute balance after introducing controlled drainage. The results showed that introducing controlled drainage reduced the drain discharge and increased the groundwater storage in the field. To achieve this, the overflow levels have to be elevated in early spring, before the drain discharge stops due to dryer conditions and falling groundwater levels. The groundwater storage in the field would have been larger if the water levels in the adjacent ditch were controlled as well by an adjustable weir. The N concentrations and loads increased, which was largely related to elevated concentrations in one of the three monitored tube drains. The P loads via the tube drains reduced due to the reduction in discharge after introducing controlled drainage. However, this may be counteracted by the higher groundwater levels and the larger contribution of N- and P-rich shallow groundwater and overland flow to the surface water.

Geophysical monitoring activities were an important component of the CO2 injection program at the Ketzin site, Germany. Here we report on the seismic and electrical resistivity tomography (ERT) measurements performed during the period of the site development and CO2 injection. Details on the site geology, the history of the CO2 injection operation, and petrophysical models relevant for the interpretation of the geophysical data are presented. The seismic measurements comprise 2D and 3D surface seismic surveys, vertical seismic profilings, and crosshole measurements. Apart from the measurements, results from advanced processing methods, such as impedance inversion and full-waveform inversion are also presented. In addition, results from crosshole ERT and surface-downhole ERT are presented. If operational efforts are taken into consideration we conclude that a combination of several geophysical methods is preferable given the demands of a spatiotemporally comprehensive monitoring program. We base this conclusion on that the different imaging characteristics and petrophysical sensitivities of different methods can complement each other. An important finding is, based on signal quality and reduced operational costs, that the use of permanent installations is promising. Generally, specific monitoring layouts will depend on site-specific characteristics, such as reservoir depth, availability of wells, petrophysical characteristics, and accessibility of surface locations. Given the comprehensive range of methods applied, the reported results are not only relevant to the operation of CO2 storage sites, but are also of interest to other monitoring projects dealing with fluid injection or production. © 2015 Elsevier B.V.

Three dolomite phases in the burial dolomitization system of the Nisku Formation in central Alberta

De Kaderrichtlijn Water verplicht provincies inzicht te geven in de mate waarin de grondwaterhuishouding bijdraagt aan de instandhoudingsdoelen in Natura 2000-gebieden. Dit vraagt om een beoordelingsmethode die gedragen wordt door medewerkers, managers en bestuurders in de beleidsvelden van de KRW en Natura 2000. Dit artikel introduceert een dergelijke beoordelingsmethode op basis van een gebiedsindicator die gedefinieerd is als: de areaalfractie van habitattypen waarvoor aan de abiotische randvoorwaarden wordt voldaan. De beschreven aanpak is toegepast op het Natura 2000-gebied Westduinen (ZH) en is toepasbaar voor een breed spectrum aan gebiedstypen.

The IMPACTS project investigated how impurities affect the design and operation of CO2 transport and storage processes. Experimental work and modelling have advanced the state of the art in the areas of how impurities in CO2 affect thermo-physical properties, fluid flow, corrosion, and reservoir chemical reactivity. High-quality experimental thermodynamic data were obtained to develop new reference equations of state for exhaust gases (EOS-CG). Parts of the results have been distributed as the publicly available TREND 2.0 software. The software enables modelling the true behaviour of impure CO2 mixtures, thereby increasing the fidelity of the simulations. IMPACTS also provided recommendations that relate results from parts of the CCS chain into results that relate to the entire CCS chain. They cover such areas as trade-offs between impurity levels and CCS system costs, optimized CO2 quality on a case-by-case basis for CCS chains, and design/operation of pipelines. New methodologies have been suggested for selecting the design criteria for operation of CO2 pipelines to avoid two-phase flow and running ductile fractures. This can help limit over-specifying design and reduce costs. For example, IMPACTS has shown how 4% of impurities in the CO2 can increase the power consumption for compression and processing by 50%. IMPACTS has generated a large amount of new knowledge and is an example of how a wide-reaching research program with several groups investigating different aspects of the same topic has brought the knowledge base forward while ensuring that the results are aligned. © 2016 Elsevier Ltd

The spatial distribution of reactivated fractures and fracture permeability after stimulation are key controlling factors that determine typical drainage areas, shale to well connectivity, and hydrocarbon flow rates in fractured shales. In this paper, the influence of fault and fracture populations on the permeability of fractured shales is studied using an analytical model and field data of fault and fracture populations derived from a 3D seismic survey covering the Posidonia Shale Formation in the West Netherlands Basin. The analytical model incorporates fault and fracture populations and describes the permeability of fractured shales using 3D permeability tensors for layered shale matrix, damage zone and fault core of fault zones. A model sensitivity analysis shows that bulk permeability can vary considerably, depending on permeability anisotropy in the matrix, damage zone and fault core, the orientation of matrix layers and damage zone fractures, and the location relative to the fault core. The field data shows the distribution of fault sizes and displacements and associated model input parameters in comparison to typical fault scaling relations from literature. Implications of the analysis for optimum well planning and flow stimulation using hydraulic fracturing in naturally fractured shales are given

The IMPACTS project investigated how impurities affect the design and operation of CO2 transport and storage processes. Experimental work and modelling have advanced the state of the art in the areas of how impurities in CO2 affect thermo-physical properties, fluid flow, corrosion, and reservoir chemical reactivity. High-quality experimental thermodynamic data were obtained to develop new reference equations of state for exhaust gases (EOS-CG). Parts of the results have been distributed as the publicly available TREND 2.0 software. The software enables modelling the true behaviour of impure CO2 mixtures, thereby increasing the fidelity of the simulations. IMPACTS also provided recommendations that relate results from parts of the CCS chain into results that relate to the entire CCS chain. They cover such areas as trade-offs between impurity levels and CCS system costs, optimized CO2 quality on a case-by-case basis for CCS chains, and design/operation of pipelines. New methodologies have been suggested for selecting the design criteria for operation of CO2 pipelines to avoid two-phase flow and running ductile fractures. This can help limit over-specifying design and reduce costs. For example, IMPACTS has shown how 4% of impurities in the CO2 can increase the power consumption for compression and processing by 50%. IMPACTS has generated a large amount of new knowledge and is an example of how a wide-reaching research program with several groups investigating different aspects of the same topic has brought the knowledge base forward while ensuring that the results are aligned. © 2016 Elsevier Ltd

Fractured rocks play an important role in many types of petroleum and geo-energy operations. From fractured limestone reservoirs to unconventionals, understanding the geomechanical behaviour and the dynamically coupled (dual) permeability system is paramount for optimal development of these systems. Traditionally, incorporating fracture systems in Finite Element Models, Finite Difference Models or other types of mesh-based approaches has been cumbersome for a number of reasons. Here, a simple implicit method is employed to model the transient behaviour of a fractured rock mass subjected to fluid pressure changes. Using a number of simplifying assumptions, the fractured rock mass is represented by an equivalent rock mass, for which the properties are dynamically updated during the simulation based on the local stress state. This allows for modelling of the fractured rock mass without explicitly including fractures. The model was applied to a simple example application. The results indicate that the model captures dynamic behaviour of fractures as a function of effective stress changes. Failing to account for this dynamic behaviour leads to a significant error in the BHP and does not capture the transient permeability evolution.

Satellite radar data were used to estimate subsurface model parameters of the Bergermeer gas field. Directly using combinations of the line-of-sight measurements in both ascending and descending satellite geometry provided an additional dimension in the data and avoided the introduction of errors during interpolation to horizontal and vertical movements. The model parameters were constrained using an Ensemble Smoother with Multiple Data Assimilation. A good match was obtained, with realistic values for the reservoir compaction coefficient and of the subsurface elastic moduli. The resulting compaction coefficients for the aquifers were interpreted with the use of geologic and reservoir knowledge: we concluded that the aquifers furthest away from the gas field were not connected to the reservoir. © 2015 Elsevier Ltd.

Hydrocarbon provinces require a high level of geological understanding in order to extend the lives of producing fields, to replace reserves through smaller targets and to reduce the risks of exploring for more and more subtle hydrocarbon traps. Despite a large number of existing wells in the area studied in this paper, the depositional environments and the stratigraphic architecture were still poorly known. In order to improve the geological understanding, we propose a workflow to assess the remaining reservoir potential of mature hydrocarbon areas, integrating cores, cuttings, well-logs

The Rupelian clay in the Netherlands is currently the subject of a feasibility study with respect to the storage of radioactive waste in the Netherlands (OPERA-project). Many features need to be considered in the assessment of the long-Term evolution of the natural environment surrounding a geological waste disposal facility. One of these is permafrost development as it may have an impact on various components of the disposal system, including the natural environment (hydrogeology), the natural barrier (clay) and the engineered barrier. Determining how deep permafrost might develop in the future is desirable in order to properly address the possible impact on the various components. It is expected that periglacial conditions will reappear at some point during the next several hundred thousands of years, a typical time frame considered in geological waste disposal feasibility studies. In this study, the Weichselian glaciation is used as an analogue for future permafrost development. Permafrost depth modelling using a best estimate temperature curve of the Weichselian indicates that permafrost would reach depths between 155 and 195ĝ€m. Without imposing a climatic gradient over the country, deepest permafrost is expected in the south due to the lower geothermal heat flux and higher average sand content of the post-Rupelian overburden. Accounting for various sources of uncertainty, such as type and impact of vegetation, snow cover, surface temperature gradients across the country, possible errors in palaeoclimate reconstructions, porosity, lithology and geothermal heat flux, stochastic calculations point out that permafrost depth during the coldest stages of a glacial cycle such as the Weichselian, for any location in the Netherlands, would be 130-210ĝ€m at the 2σ level. In any case, permafrost would not reach depths greater than 270ĝ€m. The most sensitive parameters in permafrost development are the mean annual air temperatures and porosity, while the geothermal heat flux is the crucial parameter in permafrost degradation once temperatures start rising again.

This paper describes the sedimentary architecture, chronostratigraphy and palaeogeography of the late Middle and Late Pleistocene (Marine Isotope Stage/MIS 6-2) incised Rhine-valley fill in the central Netherlands based on six geological transects, luminescence dating, biostratigraphical data and a 3D geological model. The incised-valley fill consists of a ca. 50 m thick and 10-20 km wide sand-dominated succession and includes a well-developed sequence dating from the Last Interglacial: known as the Eemian in northwest Europe. The lower part of the valley fill contains coarse-grained fluvio-glacial and fluvial Rhine sediments that were deposited under Late Saalian (MIS 6) cold-climatic periglacial conditions and during the transition into the warm Eemian interglacial (MIS 5e-d). This unit is overlain by fine-grained fresh-water flood-basin deposits, which are transgressed by a fine-grained estuarine unit that formed during marine high-stand. This ca. 10 m thick sequence reflects gradual drowning of the Eemian interglacial fluvial Rhine system and transformation into an estuary due to relative sea-level rise. The chronological data suggests a delay in timing of regional Eemian interglacial transgression and sea-level high-stand of several thousand years, when compared to eustatic sea-level. As a result of this glacio-isostatic controlled delay, formation of the interglacial lower deltaic system took only place for a relative short period of time: progradation was therefore limited. During the cooler Weichselian Early Glacial period (MIS 5d-a) deposition of deltaic sediments continued and extensive westward progradation of the Rhine system occurred. Major parts of the Eemian and Weichselian Early Glacial deposits were eroded and buried as a result of sea-level lowering and climate cooling during the early Middle Weichselian (MIS 4-3). Near complete sedimentary preservation occurred along the margins of the incised valley allowing the detailed reconstruction presented here. © 2015 Elsevier Ltd.

Lacustrine fills, including those of oxbow lakes in river floodplains, often hold valuable sedimentary and biological proxy records of palaeo-environmental change. Precise dating of accumulated sediments at levels throughout these records is crucial for interpretation and correlation of (proxy) data existing within the fills. Typically, dates are gathered from multiple sampled levels and their results are combined in age-depth models to estimate the ages of events identified between the datings. In this paper, a method of age-depth modelling is presented that varies the vertical accumulation rate of the lake fill based on continuous sedimentary data. In between Bayesian calibrated radiocarbon dates, this produces a modified non-linear age-depth relation based on sedimentology rather than linear or spline interpolation.The method is showcased on a core of an infilled palaeomeander at the floodplain edge of the river Rhine near Rheinberg (Germany). The sequence spans from ~4.7 to 2.9 ka cal BP and consists of 5.5 m of laminated lacustrine, organo-clastic mud, covered by ~1 m of peaty clay. Four radiocarbon dates provide direct dating control, mapping and dating in the wider surroundings provide additional control. The laminated, organo-clastic facies of the oxbow fill contains a record of nearby fluvial-geomorphological activity, including meander reconfiguration events and passage of rare large floods, recognized as fluctuations in coarseness and amount of allochthonous clastic sediment input. Continuous along-core sampling and measurement of loss-on-ignition (LOI) provided a fast way of expressing the variation in clastic sedimentation influx from the nearby river versus autochthonous organic deposition derived from biogenic production in the lake itself. This low-cost sedimentary proxy data feeds into the age-depth modelling. The sedimentology-modelled age-depth relation (re)produces the distinct lithological boundaries in the fill as marked changes in sedimentation rate. Especially the organo-clastic muddy facies subdivides in centennial intervals of relative faster and slower accumulation. For such intervals, sedimentation rates are produced that deviate 10-20% from that in simpler stepped linear age-models. For irregularly laminated muddy intervals of the oxbow fill - from which meaningful sampling for radiocarbon dating is more difficult than from peaty or slowly accumulating organic lake sediments - supplementing spotty radiocarbon sampling with continuous sedimentary proxy data creates more realistic age-depth modelling results. © 2016 Elsevier B.V.

Four sessions on "Monitoring Strategies: temporal trends in groundwater and surface water quality and quantity" at the EGU conferences in 2012, 2013, 2014, and 2015 and a special issue of HESS form the background for this overview of the current state of high-resolution monitoring of nutrients. The overview includes a summary of technologies applied in high-frequency monitoring of nutrients in the special issue. Moreover, we present a new assessment of the objectives behind high-frequency monitoring as classified into three main groups: (i) improved understanding of the underlying hydrological, chemical, and biological processes (PU); (ii) quantification of true nutrient concentrations and loads (Q); and (iii) operational management, including evaluation of the effects of mitigation measures (M). The contributions in the special issue focus on the implementation of high-frequency monitoring within the broader context of policy making and management of water in Europe for support of EU directives such as the Water Framework Directive, the Groundwater Directive, and the Nitrates Directive. The overview presented enabled us to highlight the typical objectives encountered in the application of high-frequency monitoring and to reflect on future developments and research needs in this growing field of expertise. © Author(s) 2016.

Faults and fractures in hydrocarbon reservoirs are key to some major production issues including (1) varying productivity of different well sections due to intersection of preferential flow paths with the wellbore, (2) varying hydrocarbon column heights in different reservoir compartments due to differences in the sealing capacity of faults, and (3) water breakthrough along preferential flow paths in case of production assisted by water injection. Dynamic coupling of mechanical responses to flow and properties of faults and fracture networks should be incorporated in the geomechanical analysis of reservoir behaviour during injection and production. In particular, if local stress changes lead to fault reactivation. In this paper, a geomechanical production optimization workflow is presented that includes well-based models of local stress state and geomechanical reservoir properties, analytical or generic numerical models to perform sensitivity studies, and full field numerical models of the 3D spatial distribution of stress and deformation. The models determine fracture-controlled reservoir behaviour that can be used to perform geomechanical production optimization. It determines the optimum conditions for injection and depletion to achieve maximum hydrocarbon production with a minimum number of wells and a minimum number of stimulation operations, taking into account reactivation of faults and fractures.

The Uddelermeer is a unique lake for The Netherlands, containing a sediment record that continuously registered environmental and climatic change from the late Pleistocene on to the present. A 15.6-m-long sediment record was retrieved from the deepest part of the sedimentary basin and an age–depth model was developed using radiocarbon dating, 210Pb dating, and Bayesian modeling. Lake-level change was reconstructed using a novel combination of high-resolution palaeoecological proxies (e.g. pollen, non-pollen palynomorphs, chironomids), quantitative determinations of lake-level change (ground-penetrating radar), and estimates of changes in precipitation (lipid biomarker stable isotopes). We conclude that lake levels were at least as high as present-day water levels from the late glacial to 3150 cal. yr BP, with the exception of at least one lake-level lowstand during the Preboreal period. Lake levels were ca. 2.5 m lower than at present between 3150 and 2800 cal. yr BP, which might have been the result of a change in moisture source region prior to the so-called 2.8-kyr event. Increasing precipitation amounts around 2800 cal. yr BP resulted in a lake-level rise of about 3.5–4 m to levels that were 1–1.5 m higher than at present, in line with increased precipitation levels as inferred for the 2.8-kyr event from nearby raised bog areas as well as with reconstructions of higher lake levels in the French Alps, all of which have been previously attributed to a phase of decreased solar activity. Lake levels decreased to their present level only during recent times, although the exact timing of the drop in lake levels is unclear. © The Author(s) 2016.

We present an interpolation model that describes Holocene groundwater level rise and the creation of accommodation space in 3D in the Rhine-Meuse delta – the Netherlands. The model area (ca. 12 400 km2) covers two palaeovalleys of Late Pleistocene age (each 30 km wide) and the overlying Holocene deposits of the Rhine-Meuse delta, the Holland coastal plain, and the Zuiderzee former lagoon. Water table rise is modelled from 10 800 to 1000 cal. BP, making use of age-depth relations based on 384 basal peat index points, and producing output in the form of stacked palaeo groundwater surfaces, groundwater age-depth curves, and voxel sets. These products allow to resolve (i) regional change and variations of inland water table slopes, (ii) spatial differences in the timing and pacing of transgression, and (iii) analysis of interplay of coastal, fluvial and subsidence controls on the provision of accommodation space. The interpolation model is a multi-parameter trend function, to which a 3D-kriging procedure of the residuals is added. This split design deploys a generic approach for modelling provision of accommodation space in deltas and coastal lowlands, aiming to work both in areas of intermediate data availability and in the most data-rich environments. Major provision of accommodation space occurred from 8500 cal BP onwards, but a different evolution occurred in each of the two palaeovalleys. In the northern valley, creation of accommodation space began to stall at 7500 cal BP, while in the southern valley provision of new accommodation space in considerable quantities continued longer. The latter is due to the floodplain gradient that was maintained by the Rhine, which distinguishes the fluvial deltaic environment from the rest of the back-barrier coastal plain. The interpolation results allow advanced mapping and investigation of apparent spatial differences in Holocene aggradation in larger coastal sedimentary systems. Furthermore, they provide a means to generate first-order age information with centennial precision for 3D geological subsurface models of Holocene deltas and valley fills. As such, the interpolation is of use in studies into past and present land subsidence and into low land sedimentation.

This paper describes the sedimentary architecture, chronostratigraphy and palaeogeography of the late Middle and Late Pleistocene (Marine Isotope Stage/MIS 6-2) incised Rhine-valley fill in the central Netherlands based on six geological transects, luminescence dating, biostratigraphical data and a 3D geological model. The incised-valley fill consists of a ca. 50 m thick and 10-20 km wide sand-dominated succession and includes a well-developed sequence dating from the Last Interglacial: known as the Eemian in northwest Europe. The lower part of the valley fill contains coarse-grained fluvio-glacial and fluvial Rhine sediments that were deposited under Late Saalian (MIS 6) cold-climatic periglacial conditions and during the transition into the warm Eemian interglacial (MIS 5e-d). This unit is overlain by fine-grained fresh-water flood-basin deposits, which are transgressed by a fine-grained estuarine unit that formed during marine high-stand. This ca. 10 m thick sequence reflects gradual drowning of the Eemian interglacial fluvial Rhine system and transformation into an estuary due to relative sea-level rise. The chronological data suggests a delay in timing of regional Eemian interglacial transgression and sea-level high-stand of several thousand years, when compared to eustatic sea-level. As a result of this glacio-isostatic controlled delay, formation of the interglacial lower deltaic system took only place for a relative short period of time: progradation was therefore limited. During the cooler Weichselian Early Glacial period (MIS 5d-a) deposition of deltaic sediments continued and extensive westward progradation of the Rhine system occurred. Major parts of the Eemian and Weichselian Early Glacial deposits were eroded and buried as a result of sea-level lowering and climate cooling during the early Middle Weichselian (MIS 4-3). Near complete sedimentary preservation occurred along the margins of the incised valley allowing the detailed reconstruction presented here. © 2015 Elsevier Ltd.