European Basin Research Articles

Timing of canyon-fed turbidite deposition in a rifted basin: The Early Cretaceous turbidite complex of the Cerrajón Formation (Subbetic, Southern Spain)

The Subbetic Cerrajón Formation of latest Hauterivian–earliest Late Albian age is made up of turbidite sandstones and calcarenites intercalated in marly-limestones and marls. It can be defined as a turbidite complex with three distinct intervals where turbidites are recorded: latest Hauterivian–Barremian p.p., Late Aptian p.p. and Middle to middle-late Albian age. The distribution of four biochronostratigraphic units of these ages throughout the studied outcrops is shown. The main hiatuses, latest Barremian–early Late Aptian and latest Aptian–early Late Albian, mainly the latter, have been identified in many other outcrops of the Southern Tethys, and are related to tectonics and associated palaeogeographic and palaeoceanographic changes. Platform environments, as the source area of the clastics, the feeding submarine canyon, base-of-slope channels and related basinal lobes or sheet systems, have been identified and can be traced laterally along more than 80 km of discontinuous outcrops aligned in a downcurrent direction. The system could have extended more than 150 km in length. The mean palaeocurrent direction fits well with the present alignment of the outcrops and, after corrections for tectonics rotation, with the current palaeogeographic model of the Southern Iberian Continental Palaeomargin (SICP). This conclusion largely supports previous interpretations of a longitudinal pattern for the distribution of clastics during the Cretaceous in that part of the SICP. The ages of the main Cretaceous events deduced from the study of the Cerrajón Formation correlate quite well with the sequence sets and subsidence history of the Prebetic Zone, where the Cretaceous platform environments adjacent to the turbidite basin are recorded. Moreover, the main unconformities dated, such as the onset and the end of turbidite sedimentation, show good correlation with the sequence boundaries described for the European basins. The analysis in time and space of the turbidite distribution and its correlation with the Prebetic carbonate platforms enables us to outline some interesting conclusion that might be a suitable subject for future research.

Changes in Nutrient Emissions, Fluxes and Retention in a North-Eastern European Lowland Drainage Basin

Despite dramatic reductions in the 1990s of N and P emissions in the drainage basin, Lake Peipsi/Chudskoe (Estonia/Russia) is still suffering from algal blooms, probably caused by low N:P ratios of the lake water. To quantify the sources and changes of N and P inputs to the lake as a result of economic changes, we modelled emissions, transfer and in-stream retention using a GIS model. The model was calibrated using river monitoring data from the 1985-1989 period, and used to simulate emissions and loads for five future scenarios for 2015-2019. During the 1985-1999 period, diffuse P emissions decreased relatively more than N diffuse emissions, but this was not reflected in the loads to the lake. P loads decreased relatively less than N loads, which caused a decrease in the N:P ratio of the rivers. About 30-45% of diffuse N emissions and only 3-10% of diffuse P emissions reaches the river network. In-stream retention reduces N and P loads to the lake by about 62% and 72%, respectively. Point sources contribute negligibly to the N load to the lake, but form about one-third of the P load. A target/fast development scenario is the most likely scenario for the 2015-2019 period, resulting in higher nutrient loads than in recent years. We conclude that effective load reductions can be achieved by focussing on diffuse N and P emissions close (< 50 km2) to the lake and by upgrading P removal capacity in wastewater treatment plants of towns.

Stakeholder participation and the water framework directive: The case of the Ribble Pilot

The Water Framework Directive is the most significant piece of European water legislation to date. This paper looks at the Directive's stakeholder participation requirements, which are crucial to its successful implementation, and represent one of its most novel and potentially far-reaching elements. The Ribble catchment in northwest England is part of a European pilot river basin network tasked by the European Commission with testing the Directive's common implementation strategy guidance, which is designed to aid member states in meeting its requirements. The Ribble pilot, managed by the Environment Agency, is responsible for testing the stakeholder participation element of this guidance. This paper provides an overview of the early stages of the Ribble pilot'sapproach, and discusses stakeholder participation in the context of the Water Framework Directive more broadly.

Sediment Load and Suspended Sediment Concentration Prediction

Sediment is a natural component of riverine environments and its presence in river systems is essential. However, in many ways and many places river systems and the landscape have been strongly affected by human activities which have destroyed naturally balanced sediment supply and sediment transport within catchments. As a consequence a number of severe environmental problems and failures have been identified, in particular the link between sediments and chemicals is crucial and has become a subject of major scientific interest. Sediment load and sediment concentration are therefore highly important variables that may play a key role in environment quality assessment and help to evaluate the extent of potential adverse impacts. This paper introduces a methodology to predict sediment loads and suspended sediment concentrations (SSC) in large European river basins. The methodology was developed within an MSc research study that was conducted in order to improve sediment modelling in the GREAT-ER point source pollution river modelling package. Currently GREAT-ER uses suspended sediment concentration of 15 mg/l for all rivers in Europe which is an obvious oversimplification. The basic principle of the methodology to predict sediment concentration is to estimate annual sediment load at the point of interest and the amount of water that transports it. The amount of transported material is then redistributed in that corresponding water volume (using the flow characteristic) which determines sediment concentrations. Across the continent, 44 river basins belonging to major European rivers were investigated. Suspended sediment concentration data were collected from various European basins in order to obtain observed sediment yields. These were then compared against the traditional empiric sediment yield estimators. Three good approaches for sediment yield prediction were introduced based on the comparison. The three approaches were applied to predict annual sediment yields which were consequently translated into suspended sediment concentrations. SSC were predicted at 47 locations widely distributed around Europe. The verification of the methodology was carried out using data from the Czech Republic. Observed SSC were compared against the predicted ones which validated the methodology for SSC prediction.

Investigation of the fate of nitrogen in Palaeozoic shales of the Central European Basin

Nitrogen geochemistry of Upper Carboniferous shales from the Central European Basin (CEB) was investigated by elemental analysis, stable isotope mass spectrometry and non-isothermal pyrolysis. Total N-contents of Namurian shales from four deep wells (4400–7000 m) in NE Germany ranged between 520 and 2680 ppm. Up to 90% of this nitrogen occurs as ammonium in minerals with δ 15N values between + 1‰ and + 3.5‰. Low nitrogen contents (down to 460 ppm) and high δ 15N values (up to + 5.6‰) in one well in the basin centre suggest a large-scale release of nitrogen associated with isotopic fractionation. Pyrolytic liberation of N 2 from pelagic Namurian A shales of NW and NE Germany occurred at significantly lower temperatures than from paralic Namurian B shales and terrestrial Westphalian samples. On-line isotope analysis of N 2 liberated between 400 and 1200 °C indicates the presence of precursor pools with different thermal stability and nitrogen isotopic composition.

Late Permian to Early Triassic transition in central and NE Spain: biotic and sedimentary characteristics

Abstract The Late Permian to Early Triassic (P/T) transition represents one of the most important Phanerozoic mass extinction episodes. Data from this transitional period are very scarce in continental basins, and reliable correlation with marine series is still a matter of debate. In this paper, information on the P/T transition in the continental series of central and NE Spain and the Balearic Islands is presented and compared with some coeval western European basins. The Iberian Ranges sections contain detailed information on the P/T transition, with sediments interpreted as alluvial fans, sandy and gravelly braided rivers and high sinuosity rivers with extensive floodplains, dated by means of pollen and spore assemblages. However, the fossil record contains two barren intervals throughout the study area, one in the Late Permian (Thuringian) and another during the latest Permian to Early Triassic. The possible causes of these gaps include the very likely relationship with the emplacement of the basaltic large igneous provinces (LIP) of SE China and western Siberia during this period of time.

Carboniferous-Permian actinopterygian fishes of the continental basins of the Bohemian Massif, Czech Republic: an overview

Abstract The actinopterygian fishes from the continental Westphalian to the Lower Permian basins in the Czech Republic are reviewed and compared with those of deposits of equivalent age in some central and western European Basins. Nine genera of actinopterygians belonging to eight families are known from the Westphalian-Stephanian sediments, and five genera belonging to four families are known from the Early Permian sediments of the Bohemian Massif. The new family Sceletophoridae is erected for the genus Sceletophorus from the Westphalian D. Very close relationships of the actinopterygian fauna between the Bohemian Massif and especially the basins of the French Massif Central are discussed.

Constraints on the tectonic evolution of the Central European Basin System revealed by seismic reflection profiles from Northern Germany

AbstractA selection of reflection-seismic lines from the southern part of the Central European Basin System and its southern margin were used to establish the spectrum of extensional and compressional deformation structures and to calibrate the timing of these events. The lines are arranged in a N-S and an E-W transect running across the Pompeckj Block and the Lower Saxony Basin in Northern Germany. The structural record provided by the seismic data points to an interplay between far-field horizontal stresses and vertical movements of the basin floor, the latter only weakly correlated with the development of seismic-scale tectonic structures. A detailed seismo-stratigraphic analysis indicates that Late Triassic-Jurassic extension has been the principal control on the structure of the E-W profile, whereas the N-S profile is dominated by compressional structures associated with Late Cretaceous inversion. Overprint effects of extension and inversion tectonics can be classified among a few distinct tectonic events accompanied by movements of the Upper Permian salt: firstly, an episode of subsidence and diapiric rise in the Keuper; secondly, a clear Jurassic-to-Early Cretaceous extension recorded by normal faulting and differential subsidence. The latter was interrupted by a major episode of Late Jurassic uplift. Thirdly, a Late Cretaceous-Early Paleogene basin inversion was associated with approximately N-S compression; and fourthly, recurring extension during the Cenozoic associated with diapiric rise and collapse. The Mesozoic extension is expressed in a number of normal faults that were most active during the Early Cretaceous localised subsidence within the Lower Saxony Basin. The deformation associated with the Late Cretaceous inversion was partly decoupled along the salt. The compressional deformation at the southern margin of the basin was thick-skinned in style, characterized by folding and faulting of the Mesozoic sedimentary fill and pre-Zechstein strata. Further north, towards the centre of the basin, folding and reverse faulting were mostly concentrated above the salt. The tectonic evolution of the investigated area suggests the presence of a zone of crustal weakness along the SW margin of the Central European Basin System which allowed strain localization in response to a favourable oriented stress field.

Facies, cycles, and controls on the evolution of a keep‐up carbonate platform (Kimmeridgian, Swiss Jura)

AbstractDuring the Late Jurassic, accelerated ocean‐floor spreading and associated sea‐level rise were responsible for a worldwide transgression, which reached its maximum in the Late Kimmeridgian. In many Western European basins, this major sea‐level rise led to the formation of marly and condensed sections. In the Swiss Jura, however, a shallow carbonate platform kept growing and only subtle changes in the stratigraphic record suggest an increasingly open‐marine influence. Field observations and thin‐section analyses reveal that the central Swiss Jura was at that time occupied by tidal flats and by more or less open marine lagoons where shoals and bioherms developed. The evolution through time of sedimentary facies and bed thicknesses permits the definition of small‐, medium‐, and large‐scale depositional sequences. The diagnostic features of these sequences are independent of scale and seem largely controlled by the Kimmeridgian second‐order transgression. A high‐resolution sequence‐stratigraphic correlation with biostratigraphically well‐dated hemipelagic and pelagic sections in the Vocontian Basin in France reveals that: (i) The most important increase in accommodation recorded in the Kimmeridgian of the central Swiss Jura occurs in the Eudoxus ammonite zone (Late Kimmeridgian) and corresponds to the second‐order maximum flooding recognized in many sedimentary basins. (ii) The small‐ and medium‐scale sequences have time durations corresponding to the first and second orbital eccentricity cycle (i.e. 100 and 400 ka, respectively), suggesting that sedimentation on the platform and in the basin was at least partly controlled by cyclic environmental changes induced by insolation variations in the Milankovitch frequency band. The comparison of the high‐resolution temporal framework defined in the Swiss Jura and Vocontian Basin with the sequence‐stratigraphic interpretation realized in other Western European basins shows that the large‐scale sequence boundaries defined in the Kimmeridgian of the Swiss Jura appear in comparable biostratigraphic positions in most Western European basins. Discrepancies that occur are probably because of local or regional tectonics.

The catchment approach as the scientific basis of river basin management

Human impacts on river systems worldwide create a compelling case for effective river basin management. This paper examines the strengths and weaknesses of this approach and the role of science in underpinning it. There are many practical reasons for adopting integrated catchment management (ICM): achieving sustainable use of water resources demands a catchment approach to problems of water quality and quantity. Together with philosophical and economic arguments for nature conservation, and the legislative requirements laid down in the EC Water Framework Directive (WFD), the need for ICM is undeniable. In practice, however, ICM is hindered by significant gaps in scientific understanding. Some are geographical (e.g. inadequate knowledge of headwaters), some ecological (e.g. links between catchment processes, habitats, and aquatic species) while some relate to scale (e.g. extrapolating small-scale observations to entire catchments). The WFD is playing an increasing role in European river basin management, yet technical tasks such as defining 'reference conditions' or classifying 'ecological status' are hampered by inadequate scientific knowledge. It is essential that the results of scientific studies are made widely available, both through peer-reviewed publications and by conversion into practical guidelines or manuals for river engineers and managers. Although the river basin is a logical and defensible unit for conservation and management, the paper concludes that an even wider perspective is needed. Supra-catchment pressures from acid deposition or invasive alien species pose serious threats to rivers: efforts to tackle these issues cannot be confined to catchment units but must look out beyond the watershed.

Multiphase salt tectonic evolution in NW Germany: seismic interpretation and retro-deformation

The Central European Basin is a classic area of salt tectonics, characterized by heterogeneous structural evolution and complex salt movement history. We studied an area on its SW margin, based on prestack depth-migrated 2D and 3D seismic data. We use seismic interpretation and retro-deformation to obtain a better understanding of salt tectonics, structural control, and sedimentary response in this region. The first phase of salt tectonic evolution started with two main events of NW–SE extension and rafting in the Triassic before the Upper Bunter and before the Upper Muschelkalk. Rafting was accompanied by first salt diapirism and an increased sedimentary thickness adjacent to the salt structure. After salt supply ceased updip to the salt structure, a mini-basin grew in the intra-raft area. This sedimentary differential loading caused salt movement and growth of a pillow structure basinward. The second phase of salt movement was initiated by the formation of a NNW–SSE striking basement graben in the Middle Keuper that triggered reactive diapirism, the breakthrough of the pillow’s roof and salt extrusion. The following downbuilding process was characterized by sedimentary wedges with basal unconformities, onlap structures and salt extrusions that ceased in the Jurassic. The third and latest phase of salt tectonic evolution was activated in the Late Cretaceous to Lower Tertiary by compressional tectonics indicated by salt rise and a small horizontal shortening of the diapir. The interpreted salt tectonic processes and the resulting geometries can now be better tied in with the regional heterogeneous framework of the basin.

Contrasting red bed diagenesis: the southern and northern margin of the Central European Basin

We compare the diagenetic evolution of deeply buried Rotliegend (Permian) red bed sandstones at the southern and northern margin of the Central European Basin (CEB) in Germany. Main target is to evaluate the influence of maturation products from hydrocarbon (HC) source rocks during red bed diagenesis. At the southern margin of the CEB, thick coal-bearing Carboniferous source rocks are omnipresent beneath the Rotliegend. They contain dominantly gas-prone terrigenous organic material and some oil source rocks. Hydrocarbons were generated from Late Carboniferous onwards throughout most of basin subsidence. At the northern margin of the CEB, source rocks are almost absent due to deep erosion of Carboniferous rocks and a low TOC of local Lower Carboniferous relics. Early diagenetic processes are comparable at both basin margins. Significant differences in burial diagenetic evolution are spatially correlated to the occurrence of hydrocarbon source rocks. Burial diagenesis at the southern margin of the CEB is characterized especially by bleaching of red beds, major dissolution events, pervasive illite formation, impregnation of pore surfaces with bitumen, and formation of late Fe-rich cements. Almost none of these features were detected at the northern basin margin. Instead, relatively early cements are preserved down to maximum burial depths. This suggests that major diagenetic mineral reactions in deeply buried red bed sandstones are controlled by the presence or absence of maturing hydrocarbon source rocks.

The significance of fixed ammonium in Palaeozoic sediments for the generation of nitrogen-rich natural gases in the North German Basin

In contrast to predominantly hydrocarbon-rich natural gases in the western part of the Central European Basin (CEB), accumulations of natural gases from the eastern part of the North German Basin (NGB) are nitrogen-rich with up to 90% N2. This study is focused on the behaviour of fixed ammonium in clay minerals of organic-rich Palaeozoic sediments in the eastern part of the NGB as a major source of nitrogen-rich natural gases. Carboniferous shales have been investigated for a better understanding of nitrogen fixing during diagenesis, storage during burial and release during devolatilization processes or fluid–rock interactions. The total nitrogen contents in the studied Carboniferous shales of the NGB reach up to 2700 ppm with an inorganic fixed portion (in the form of NH4+–N) of more than 60%. The results of this study indicate an increasing proportion of the mineralogically fixed ammonium with increasing thermal maturity and storage up to catagenetic conditions. The isotopic composition of fixed-NH4 is relatively homogeneous in the majority of the shales and ranges from +1 to +3.5‰. In contrast, samples from the basin centre show a significant decrease in ammonium contents down to 460 ppm coupled with a shift in δ15N up to +5.6‰ suggesting a release of nitrogen on a large scale. Calculation of nitrogen loss and isotopic fractionation indicate that more than 30% of nitrogen was released as ammonium probably as a consequence of fluid-rock interaction with highly saline brines.

Dynamics of sedimentary basins: the example of the Central European Basin system

Dynamics of sedimentary basins: the example of the Central European Basin system

Numerical modelling of burial and temperature history as an approach for an alternative interpretation of the Bramsche anomaly, Lower Saxony Basin

The Lower Saxony Basin, Germany, is one of the several sedimentary basins within the Central European Basin system. In its southwestern part, anomalously high maturity of organic matter has been observed to reach 4.5% VRr in Upper Jurassic and Lower Cretaceous sedimentary rocks in an area which coincides with a magnetic and a positive gravimetric anomaly. This anomaly was often interpreted as the consequence of a deep-seated igneous intrusion, the so-called Bramsche Massif. However, results obtained from calibrated numerical modelling are not in accordance with this scenario. Instead, a burial by approximately 4 km of now-eroded Cretaceous rocks was revealed to be the probable cause for the anomaly. Data and modelling results from six boreholes and two pseudo-wells support this view.

Investigation of the pyrolytic liberation of molecular nitrogen from Palaeozoic sedimentary rocks

Open-system non-isothermal pyrolysis up to 1,200°C in combination with elemental analysis was used to study the thermal liberation of molecular nitrogen (N2) from sedimentary rocks and kerogen concentrates of Palaeozoic age from the Central European Basin system and an Eocene shale (Liaohe Basin, China) with a high content (36%) of ammonium feldspar (buddingtonite). The N/Corg (atomic) ratios of the kerogen concentrates ranged from 0.005 to 0.014, which represents the range commonly observed for coals. Bulk N/Corg ratios of the Palaeozoic shales extended from 0.035 to 0.108, indicating the presence of significant amounts of inorganic nitrogen. Namurian A and A-B (CnA; CnA-B) samples typically exhibited the earliest onset of N2 generation with intense, characteristic peaks around 600°C. N2 liberation from the buddingtonite-rich sample occurred at higher temperatures, with a broad peak around 700°C. Pyrograms of the kerogen concentrates showed no or strongly reduced N2 generation in the 500–700°C range. On-line isotope-specific analysis of the pyrolytically liberated N2 on one sample revealed a variability of ∼10‰ in the δ15N values and a steady increase in δ15N with temperature during the main phase of N2 generation.

Synsedimentary faults and amalgamated unconformities: Insights from 3D-seismic and core analysis of the Lower Triassic Middle Buntsandstein, Ems Trough, north-western Germany

The Late Permian/Early Triassic succession of the Central European Basin (CEB) was repeatedly affected by the tectonic pulses associated with the earliest phases of Tethyan and Arctic–North Atlantic rifting. Effects of the differential tectonic subsidence are particularly well recorded by unconformities, which form widespread sequence boundaries. Such unconformities are most obvious in areas occupied by fault-controlled intra-basinal highs (swells). In that areas, stratigraphic loss may comprise entire Lower and Middle Buntsandstein formations and in places remnant Middle Buntsandstein successions directly rest on Permian strata. Analysis of 3D-seismic data and well logs combined with high-resolution sedimentological logging of drillcores at the western margin of the Ems Trough (NW Germany) reveals details of synsedimentary tectonic control on sequence development. Early Triassic extensional faulting of basement blocks provided stepwise addition of accommodation space for continental sequences by growth faulting along north–south oriented fault zones blocks on the flanks of the East Netherlands High. This process is most evident during the development of the Hardegsen Unconformity, which is characterised by an amalgamation of succeeding unconformity surfaces in areas of structurally controlled intrabasinal highs.

Thermal maturity in the Central European Basin system (Schleswig-Holstein area): results of 1D basin modelling and new maturity maps

Thermal maturity information has been compiled for one of the deepest parts of the Central European Basin system, the Schleswig-Holstein area in northern Germany. New vitrinite reflectance data were obtained and old data were evaluated from a total of 31 wells. Furthermore, numerical 1D basin modelling was performed in order to interpolate/extrapolate vitrinite reflectance data to base Zechstein and base Keuper. For these two horizons, maturity maps were finally compiled revealing large differences in present-day thermal maturity within the basin. For example, vitrinite reflectance at base Zechstein ranges from greater than 4.5% in the Glueckstadt Graben to less than 1% in the northern part of the study area. Highest thermal maturity of base Keuper occurs in the West Holstein Trough and in the northern part of the Glueckstadt Graben. The timing of maturation is greatly affected by the complex tectonic evolution of the area. For six key wells distributed over the entire study area, burial and temperature histories as well as evolution of maturity were evaluated using 1D basin modelling. Deepest burial and maximum temperatures occurred either during Jurassic, Upper Cretaceous or Neogene times in these wells. Only some parts of the sedimentary package in Schleswig-Holstein show a significant increase in maturity during the Tertiary leading to additional hydrocarbon generation and entrapment.

Depositional architecture and transgressive–regressive cycles within Liassic backstepping carbonate ramps in the Basque–Cantabrian basin, northern Spain

An integrated stratigraphical, sedimentological, geochemical and sequential analysis has been carried out on the Liassic rocks of the Basque–Cantabrian basin in northern Spain using outcrop and subsurface data. The study documents the progressive drowning and backstepping of an epeiric carbonate ramp that originated during the worldwide late Triassic–early Jurassic transgression. Two major carbonate depositional systems have been recognized within the drowning succession: (1) a late Triassic–early Sinemurian shallow-marine ramp, which reflects a progressive marine transgression over Triassic continental deposits; (2) a late Sinemurian–Toarcian set of hemipelagic ramps, which recorded the progressive drowning and backstepping of the ramp system during a second major event of marine flooding. Sequence stratigraphic analysis of the Liassic succession has revealed that transgressive–regressive trends constitute the most evident cyclicity. A major transgressive–regressive cycle and six subsidiary transgressive–regressive facies cycles have been defined in the basin and compared with those defined in other European basins. Although a good correlation exists for the major transgressive–regressive cycle, significant discrepancies have been found for the number, limits and extent of the transgressive–regressive facies cycles reflecting the effects of local tectonics. The overall backstepping within the Basque–Cantabrian basin resulted in a dominance of transgressive episodes across a range of different scales. Accordingly, regressive intervals are less well developed except during limited periods of active tectonics as occurred in the mid-Sinemurian. These progressively longer and deeper marine flooding intervals, followed by relative stillstand or minor sea-level falls, are interpreted to reflect high thermal subsidence rates coupled with a Liassic eustatic transgression.

Variation of the present-day stress field within the North German Basin—insights from thin shell FE modeling based on residual GPS velocities

We present a finite element-based dynamic modeling study of the recent stress conditions within the North German Basin, which is part of the Central European Basin System, based on geological, geophysical and geomorphological data. After compilation and evaluation of existing data, thin shell modeling is applied to understand the recent structural evolution of the Central European Basin System (CEBS) and its transition towards the Baltic Shield. In contrast to previous modeling approaches, we include a complex pattern of major faults from the Alpine Front to the Sorgenfrei–Tornquist Zone (STZ) and GPS measured residual velocities to define the boundary conditions of the model. Major deviations of the stresses occur along strong contrasts in the lithospheric structure and influence the stress pattern significantly. High intraplate compression is a responsible large-scale reactivation of the faults associated with the pre-existing basin framework in northern Central Europe, with an important record on vertical motions. The modeled slip/subsidence rates of the faults in the North German Basin are in the order of 0.01 and 0.2 mm year −1, which are in accordance with field observations, because no fault exhibits large Quaternary displacement rates in the study area.