Rhine Graben Research Articles

Cameralism and the production of space in the eighteenth-century Romanian Banat: the grid villages of the ‘Danube Swabians’

This article addresses the origin, morphology and significance of planned villages associated with the Habsburg colonization of the Romanian Banat, a region in east-central Europe comprising parts of present day Serbia, Romania and Hungary, in the eighteenth century. In an effort to repopulate and bring into agricultural production a territory that had been devastated by warfare, the Habsburg state under Maria Theresa and Joseph II devised and directed a series of large scale, systematic efforts to colonize the region, primarily with German speaking farmers from the upper Rhine valley. One of the most distinctive features of the cultural landscape produced by this colonization was dozens of centrally planned agricultural villages featuring Baroque architectural elements. Most of these villages adhered to a regular, rectilinear form, but other forms, such as street villages and circular hamlets, were employed as well. Together, these town and village morphologies comprise a planned, systematic settlement pattern that is found in few other places in Europe, and as such sets the region apart. Employing fieldwork and archival research, the paper describes the characteristic elements of these villages and uses ideas of the production of space as a framework for understanding the distinctive historical-political discourses encoded in this cultural landscape.

On the Use of Aeromagnetism for Geological Interpretation: 2. A Case Study on Structural and Lithological Features in the Northern Vosges

AbstractIn many grabens of the West European Rift System, several drilling projects are targeting fluid conductive faults to produce electricity with geothermal energy. In order to reach the adequate temperatures, the targeted faults are located in the basement rocks or at the basement/cover interface. Unfortunately, the basement rock facies and structural data useful for reservoir modeling are often poorly constrained because of the lack of boreholes deeper than 2,000 m and seismic information on the deep subsurface. With the aim to outline the basement structure in the Upper Rhine Graben, two aeromagnetic surveys were conducted where the basement outcrops in the Northern Vosges, with different flight parameters and types of magnetometers. An interpolator using equivalent sources for gridding these two surveys is described by Gavazzi et al. (2020). Here, we describe the geological interpretation of these surveys. We demonstrate the consistency between the total magnetic field intensity and the outcropping lithological units organized in ENE‐WSW subvertical bands. In detail, three main blocks were delineated, separated by N‐S faults linked to the graben formation and ENE‐WSW‐inherited Hercynian faults. The latter faults, together with more local NE‐SW and NW‐SE faults, compartmentalize the N‐S‐oriented basement rocks. This is relevant for geothermal prospection where the N‐S faults are the main targets because fluid flow through other fault systems is deemed restricted. With a focus on the interface between the Northern Vosges and the Upper Rhine Graben, we also demonstrate considerable segmentation on the main graben boundary faults.

How Do Secondary Minerals in Granite Help Distinguish Paleo- from Present-Day Permeable Fracture Zones? Joint Interpretation of SWIR Spectroscopy and Geophysical Logs in the Geothermal Wells of Northern Alsace

The investigation of permeable hydrothermally altered and fractured zones and their distribution is a key issue for the understanding of fluid circulation in granitic rocks, on which the success of geothermal projects relies. Based on the use of short-wave infrared (SWIR) spectroscopy applied to rock cuttings coupled with interpretation of geophysical logs, we propose an investigation of the clay signature of fault and fracture zones (FZ) inside the granitic basement. This methodology was applied to two geothermal wells: GRT-2 from the Rittershoffen and GPK-1 from the Soultz-sous-Forêts (Soultz) geothermal sites, both located in the Upper Rhine Graben (URG). A total of 1430 SWIR spectra were acquired and analysed. Variations in the 2200 nm absorption band area are correlated with hydrothermal alteration grades. The 2200 nm absorption band area is found to reflect the illite quantity and its variations in the granitic basement. Low, stable values are observed in the unaltered granite facies, showing good reproducibility of the method, whereas scattered high values are associated with high hydrothermal alteration and FZs. Variations in the 2200 nm absorption band area were correlated with the gamma ray and electrical resistivity logs. This procedure allowed us to confirm that illite mainly controls the resistivity response except inside the permeable FZs, where the resistivity response is controlled by the geothermal brine. Thus, the architecture of these permeable FZs was described precisely by using a combination of the 2200 nm absorption band area data and the electrical resistivity log. Moreover, by correlation with other geophysical logs (temperature (T), porosity, and density), paleo-permeable and currently permeable FZs inside the reservoir were distinguished. The correlation of SWIR spectroscopy with electrical resistivity logs appears to be a robust tool for geothermal exploration in granitic reservoirs in the URG.

Heat flow density estimates in the Upper Rhine Graben using laboratory measurements of thermal conductivity on sedimentary rocks

The Upper Rhine Graben (URG) has been extensively studied for geothermal exploitation over the past decades. Yet, the thermal conductivity of the sedimentary cover is still poorly constrained, limiting our ability to provide robust heat flow density estimates. To improve our understanding of heat flow density in the URG, we present a new large thermal conductivity database for sedimentary rocks collected at outcrops in the area including measurements on (1) dry rocks at ambient temperature (dry); (2) dry rocks at high temperature (hot) and (3) water-saturated rocks at ambient temperature (wet). These measurements, covering the various lithologies composing the sedimentary sequence, are associated with equilibrium-temperature profiles measured in the Soultz-sous-Forêts wells and in the GRT-1 borehole (Rittershoffen) (all in France). Heat flow density values considering the various experimental thermal conductivity conditions were obtained for different depth intervals in the wells along with average values for the whole boreholes. The results agree with the previous heat flow density estimates based on dry rocks but more importantly highlight that accounting for the effect of temperature and water saturation of the formations is crucial to providing accurate heat flow density estimates in a sedimentary basin. For Soultz-sous-Forêts, we calculate average conductive heat flow density to be 127 mW/m2 when considering hot rocks and 184 mW/m2 for wet rocks. Heat flow density in the GRT-1 well is estimated at 109 and 164 mW/m2 for hot and wet rocks, respectively. Results from the Rittershoffen well suggest that heat flow density is nearly constant with depth, contrary to the observations for the Soultz-sous-Forêts site. Our results show a positive heat flow density anomaly in the Jurassic formations, which could be explained by a combined effect of a higher radiogenic heat production in the Jurassic sediments and thermal disturbance caused by the presence of the major faults close to the Soultz-sous-Forêts geothermal site. Although additional data are required to improve these estimates and our understanding of the thermal processes, we consider the heat flow densities estimated herein as the most reliable currently available for the URG.

Regional hydraulic model of the Upper Rhine Graben

Abstract. In this study we make use of 3-D hydraulic simulations to investigate the regional groundwater flow in the Upper Rhine Graben. The modeling is based on an existing detailed 3-D structural model covering the whole Upper Rhine Graben from the surface down to 14 km of depth. The overall goal of this study is to provide some quantitative analysis on the role of the hydraulic head topology in shaping the underground hydrodynamics by taking into account interactions with the heterogeneous subsurface sedimentary configuration of the basin system. Therefore, the main question addressed by this study can be summarized as follows: does the deep graben flow follow the topographic gradient and the flow direction of the river Rhine from the Alps northward to the northernmost area of the Upper Rhine Graben? Our results demonstrate the presence of a regional subsurface flow in the sedimentary rocks aligning from the graben flanks towards its center and in the southern half of the graben from south to north. The graben-parallel flow velocity is found to be about 1 order of magnitude lower than the velocity predicted perpendicular to the main graben axis. Besides these general trends, the modeling highlights local heterogeneities in the shallow 3-D flow field. Those arise from the interaction between regional groundwater flow and the heterogeneous sedimentary configuration. Within the Cenozoic sediments forming the uppermost aquifer in the model, groundwater flows are driven by imposed hydraulic gradients from recharge areas located at higher elevations in the Black Forest and Vosges Mountains to the discharge region at a lower elevation in the Rhine valley. The presence of a regional aquitard (Keuper) separating the shallow and the deeper aquifer system (Muschelkalk, Buntsandstein, and Rotliegend) hinders hydraulic connection among the two aquifer systems. This is exemplified by the development of a flow system in the deeper aquifers, which shows a more continuous graben-parallel south–north direction. Based on these results we can conclude that both the hydraulic head topology and the level of structuration of the sedimentary sequence exert a 1st-order role in shaping the regional flow system at depth. The regional model predicts a heterogeneous flow system within the upper 4 km of the Upper Rhine Valley, where flow velocities in the graben valley can reach up to 45 mm yr−1 in the upper and lower aquifers. Back to the current conceptual hydrogeological model, the results question the presence of a graben through northward flow, being limited to the southern half of the graben. In the north, the groundwater dynamics turn out to be more complex, being structurally linked to the local geology. This calls for additional studies with a higher level of both structural and stratigraphic attributes in order to arrive at a better quantification of the local to the regional groundwater dynamics in the area.

Sindbis virus- a wild bird associated zoonotic arbovirus circulates in Germany

Sindbis virus (SINV) is an arbovirus causing clinical symptoms such as arthritis, rash and fever following human infections in Fennoscandia. Its transmission cycle involves mosquito species as vectors as well as wild birds that act as natural reservoir hosts. In Germany, SINV was first time observed in 2009 in different mosquito species in the Upper Rhine valley and one year later in a hooded crow in Berlin. Recently, SINV was also detected repeatedly at various locations in Germany in the context of a mosquitoes monitoring program for arboviruses.In this study, we detected for just the second time a SINV infection in a diseased wild bird (common wood pigeon) from Central Europe. SINV was isolated by cell culture and the complete SINV genome sequence was determined. Phylogenetic analyses revealed a close affiliation to SINV genotype I with a high similarity to human isolate sequences from Finland, Sweden and Russia. The isolate was genetically distinct from the first avian isolate suggesting the circulation of at least two different SINV strains in Germany.In order to reveal the infection frequency in SINV positive mosquito regions 749 bird blood samples were assayed serologically and SINV antibodies found primarily in resident birds. SINV is therefore endemically circulating in mosquitoes in Germany, which results in occasional bird infections. No data are yet available on zoonotic transmission to humans.

Creep of concrete as influenced by the rate of expansion due to alkali–silica reaction

AbstractThree alkali‐sensitive and one insensitive aggregate were used in the concrete mixes. The slow reacting aggregates were greywacke from the Lower Harz, quartz porphyry from Halle and crushed gravel from the Upper Rhine valley. The insensitive aggregate was quartz porphyry from the Black Forest. The concretes showed the typical S‐shaped expansion curve in the 40°C fog room. After a certain time in the fog room, specimens were taken out and creep tests were conducted in a climate of 80% RH and 23°C. This scenario does not necessarily reproduce the situation of real structures but helps to understand the influence of ASR expansion development on creep. The creep deformation depended clearly on the preceding storage duration in the fog chamber. The largest influence on the deformation appeared at the time when the expansion rate in the fog room had a maximum.

Several Lower Palaeolithic Sites along the Rhine Rift Valley, Dated from 1.3 to 0.6 Million Years

The important discoveries of Lower Palaeolithic artefacts in stratigraphical context within Lower and early Middle Pleistocene deposits in the western continental part of Europe along the rift systeme of the Rhine Valley are pointing at the possible continuous presence of hominins since the Lower Pleistocene. This paper reports on lithic industry from its early appearance at around 1.3 million years (Ma) at the site of Münster-Sarmsheim to the latest pre-Elsterian period at around 0.6 Ma at Mauer, Mosbach, and Miesenheim.

Biogas production from submerged macrophytes\u2014a case study of regional biomass potentials in Germany

BackgroundUtilization of energy crops for biogas production has been controversially discussed in Germany due to negative environmental effects and the “food vs. fuel” debate. This led to a search for alternative substrates focusing on material from landscape management measures. Aquatic biomass is harvested during water body management, yet it has not been considered for energy generation.MethodsThe information where and which amount of biomass is collected by aquatic de-weeding operations in rivers and lakes was gathered via a nationwide survey. In addition to that, the amount of aquatic plant biomass potentially available in water bodies was estimated exemplarily for the flowing waters of Baden-Württemberg—by using data from the European Water Framework Directive surveys.ResultsThe survey revealed 172 locations of de-weeding operations in flowing waters and 93 in standing waters. These locations are concentrated in lowland rivers of the North German Plain as well as the Upper Rhine Plain. Standing water de-weeding operations were reported mainly from the foothills of the Alps. The overall amount of biomass harvested per year is 36,244 t of fresh biomass. Taking into account missing data, a maximum of 100,000 t of fresh biomass per year can be estimated for Germany. The case study on plant biomass de-weeded from waters in Germany revealed that only a small part of the total aquatic plant biomass is actually harvested.ConclusionsThe amount of biomass harvested and removed from water bodies in Germany is considerably lower than the harvest of other substrates from landscape management measures such as mowing of meadows or trimming of trees and hedges. However, larger amounts are accumulating locally, concentrated in some regions or at specific water bodies, e.g., reservoirs, for which regional value chains could be established. In order to make the exploitation of these local potentials economically viable, changes regarding the economic and technological framework are required.

Inhibitor performance on carbon steel in the geothermal environment of the Upper Rhine graben (Central Europe) – A laboratory study

The corrosion behavior of carbon steel in CO2-saturated artificial geothermal brine was tested in the absence and presence of an amine-based inhibitor by weight loss tests and electrochemical measurements. Experimental conditions were adapted to the conditions existing on the re-injection sites of geothermal power plants located in the Upper Rhine Graben. The influence of Ca2+-ions on the corrosion behavior due to scale formation and its impact on inhibitor performance was investigated. Inhibitor adsorption was strongly dependent on inhibitor concentration, Ca2+ concentration in the brine, reaction time, and pre-corrosion of the metal surface.

Locating Geothermal Resources: Insights from 3D Stress and Flow Models at the Upper Rhine Graben Scale

To be exploited, geothermal resources require heat, fluid, and permeability. These favourable geothermal conditions are strongly linked to the specific geodynamic context and the main physical transport processes, notably stresses and fluid circulations, which impact heat-driving processes. The physical conditions favouring the setup of geothermal resources can be searched for in predictive models, thus giving estimates on the so-called “favourable areas.” Numerical models could allow an integrated evaluation of the physical processes with adapted time and space scales and considering 3D effects. Supported by geological, geophysical, and geochemical exploration methods, they constitute a useful tool to shed light on the dynamic context of the geothermal resource setup and may provide answers to the challenging task of geothermal exploration. The Upper Rhine Graben (URG) is a data-rich geothermal system where deep fluid circulations occurring in the regional fault network are the probable origin of local thermal anomalies. Here, we present a current overview of our team’s efforts to integrate the impacts of the key physics as well as key factors controlling the geothermal anomalies in a fault-controlled geological setting in 3D physically consistent models at the regional scale. The study relies on the building of the first 3D numerical flow (using the discrete-continuum method) and mechanical models (using the distinct element method) at the URG scale. First, the key role of the regional fault network is taken into account using a discrete numerical approach. The geometry building is focused on the conceptualization of the 3D fault zone network based on structural interpretation and generic geological concepts and is consistent with the geological knowledge. This DFN (discrete fracture network) model is declined in two separate models (3D flow and stress) at the URG scale. Then, based on the main characteristics of the geothermal anomalies and the link with the physics considered, criteria are identified that enable the elaboration of indicators to use the results of the simulation and identify geothermally favourable areas. Then, considering the strong link between the stress, fluid flow, and geothermal resources, a cross-analysis of the results is realized to delineate favourable areas for geothermal resources. The results are compared with the existing thermal data at the URG scale and compared with knowledge gained through numerous studies. The good agreement between the delineated favourable areas and the locations of local thermal anomalies (especially the main one close to Soultz-sous-Forêts) demonstrates the key role of the regional fault network as well as stress and fluid flow on the setup of geothermal resources. Moreover, the very encouraging results underline the potential of the first 3D flow and 3D stress models at the URG scale to locate geothermal resources and offer new research opportunities.

Half a century of Krypton-85 activity concentration measured in air over Central Europe: Trends and relevance for dating young groundwater

For almost half a century weekly samples for the measurement of krypton-85 (85Kr) activity concentrations in surface air have been collected by the Bundesamt für Strahlenschutz (BfS), Germany. Sampling started at Freiburg (230m asl) in 1973, Mt Schauinsland (1205m asl) in 1976 and Mt Jungfraujoch in Switzerland (3454 asl) in 1990. Distinct maxima in the time series of atmospheric 85Kr activity concentration are caused by emissions from nuclear reprocessing plants in Europe, mainly the La Hague, France, and Sellafield, UK, reprocessing plants. Between 1970 and 1990 peak activity concentrations measured in winter along the Rhine Rift in Freiburg are often higher than at Mt Schauinsland, due to emissions from the operating pilot reprocessing plant in Karlsruhe - approximately 130 km to the north - and large-scale inversions that inhibit exchange of air masses within the Rhine Rift with those at higher altitudes. From the early 1990s onwards, after the shut-down of the pilot plant, differences between Freiburg and Schauinsland are much smaller. Activity concentrations measured at Jungfraujoch are generally lower and close to baseline levels, due to its location in the free troposphere. Weekly baseline and average 85Kr activity concentration in the atmosphere in Central Europe were modelled from almost 12,000 individual measurements at 11 stations. The baseline and average have continuously increased, interrupted by a relatively stable period between 2009 and the end of 2014 with a baseline activity concentration of about 1.39 Bq/m3. Depending on the geographical location and hydrological conditions, the modelled baseline or average 85Kr activity concentration time series can be used as input functions for the dating of young groundwater.

Understanding atmospheric aerosol particles with improved particle identification and quantification by single-particle mass spectrometry

Abstract. Single-particle mass spectrometry (SPMS) is a widely used tool to determine chemical composition and mixing state of aerosol particles in the atmosphere. During a 6-week field campaign in summer 2016 at a rural site in the upper Rhine valley, near the city of Karlsruhe in southwest Germany, ∼3.7×105 single particles were analysed using a laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF). Combining fuzzy classification, marker peaks, typical peak ratios, and laboratory-based reference spectra, seven major particle classes were identified. With the precise particle identification and well-characterized laboratory-derived overall detection efficiency (ODE) for this instrument, particle similarity can be transferred into corrected number and mass fractions without the need of a reference instrument in the field. Considering the entire measurement period, aged-biomass-burning and soil-dust-like particles dominated the particle number (45.0 % number fraction) and mass (31.8 % mass fraction); sodium-salt-like particles were the second lowest in number (3.4 %) but the second dominating class in terms of particle mass (30.1 %). This difference demonstrates the crucial role of particle number counts' correction for mass quantification using SPMS data. Using corrections for size-resolved and chemically resolved ODE, the total mass of the particles measured by LAAPTOF accounts for 23 %–68 % of the total mass measured by an aerosol mass spectrometer (AMS) depending on the measurement periods. These two mass spectrometers show a good correlation (Pearson's correlation coefficient γ>0.6) regarding total mass for more than 85 % of the measurement time, indicating non-refractory species measured by AMS may originate from particles consisting of internally mixed non-refractory and refractory components. In addition, specific relationships of LAAPTOF ion intensities and AMS mass concentrations for non-refractory compounds were found for specific measurement periods, especially for the fraction of org ∕ (org + nitrate). Furthermore, our approach allows the non-refractory compounds measured by AMS to be assigned to different particle classes. Overall AMS nitrate mainly arose from sodium-salt-like particles, while aged-biomass-burning particles were dominant during events with high organic aerosol particle concentrations.

Human and animal deposits in circular pits of the 5th millennium between the Rhine and the Danube

On account of recent developments in the absolute chronology of circular-shaped grave deposits from Bavaria, new bibliographic research and a series of discoveries in the south of the Upper Rhine Plain, we can now advance the hypothesis of an origin of this phenomenon in Central Europe, between the Czech Republic and Bavaria. These regions have yielded the earliest deposits with typologies encompassing all of the defined categories: burials in conventional or non-conventional positions, asymmetrical deposits, mixed deposits, anatomic segments, etc. The introduction of this practice in the south of the Upper Rhine Plain and in the Neckar Valley, undoubtedly under the direct influence of Munchshofen, occurs in the second third of the 5th millennium: it is illustrated in particular by mixed deposits, anatomic segments, isolated individuals in conventional or non-conventional positions, singular deposits with a warrior connotation and deposits of animals. The Michelsberg culture, attested in Lower Alsace at the end of the millennium, perpetuates this practice which undergoes a new development during the middle stage of this culture and a direct diffusion towards Upper Alsace. To the east, in Slovakia, it is possible that the group from Ludanice, affected by the phenomenon during the last centuries of the 5th millennium, played a relay role in diffusion towards early Trichterbecherkultur groups.Thus, rather than a progressive diffusion of the phenomenon from the Chassean towards Michelsberg, then towards the Danubian regions, we propose a polycentric model in which South and Central Europe evolve separately without necessarily interacting.

Deposits of bodies in circular pits in the Neolithic period (mid-fifth to the mid-fourth millennium BCE)

Among the numerous human remains found in circular pits belonging to the fourth millennium BCE cultures north of the Alps, there are many examples of bodies laid in random (or unconventional) positions. Some of these remains in irregular configurations, interred alongside an individual in a conventional flexed position, can be considered as a ‘funerary accompaniment’. Other burials, of isolated individuals or multiple individuals buried in unconventional positions, suggest the existence of burial practices outside of the otherwise strict framework of funerary rites. The focus of this article is the evidence recently arising from excavation and anthropological studies from the Upper Rhine Plain (Michelsberg and Munzingen cultures). We assume that these bodies in unconventional positions were not dumped as trash, but that they were a part of the final act of a complex ritual. It is hypothesised that these bodies, interpreted here as ritual waste, were sacrificial victims, and a number of possible explanations, including ‘peripheral accompaniment’ or victims of acts of war, are debated.

Influence of the Main Border Faults on the 3D Hydraulic Field of the Central Upper Rhine Graben

The Upper Rhine Graben (URG) is an active rift with a high geothermal potential. Despite being a well-studied area, the three-dimensional interaction of the main controlling factors of the thermal and hydraulic regime is still not fully understood. Therefore, we have used a data-based 3D structural model of the lithological configuration of the central URG for some conceptual numerical experiments of 3D coupled simulations of fluid and heat transport. To assess the influence of the main faults bordering the graben on the hydraulic and the deep thermal field, we carried out a sensitivity analysis on fault width and permeability. Depending on the assigned width and permeability of the main border faults, fluid velocity and temperatures are affected only in the direct proximity of the respective border faults. Hence, the hydraulic characteristics of these major faults do not significantly influence the graben-wide groundwater flow patterns. Instead, the different scenarios tested provide a consistent image of the main characteristics of fluid and heat transport as they have in common: (1) a topography-driven basin-wide fluid flow perpendicular to the rift axis from the graben shoulders to the rift center, (2) a N/NE-directed flow parallel to the rift axis in the center of the rift and, (3) a pronounced upflow of hot fluids along the rift central axis, where the streams from both sides of the rift merge. This upflow axis is predicted to occur predominantly in the center of the URG (northern and southern model area) and shifted towards the eastern boundary fault (central model area).

Reconstructing Paleofluid Circulation at the Hercynian Basement/Mesozoic Sedimentary Cover Interface in the Upper Rhine Graben

In this paper, we focus on paleocirculation at the Hercynian basement/sedimentary cover interface in the tectonic environment of the Upper Rhine graben. The goal is to increase our understanding of the behavior of the fracture-fault network and the origin of the hydrothermal fluids. We studied orientations, mineral fillings, and fluid origins of fractures that crosscut the Hercynian granitic basement and the Permo-Triassic formations in relation to the major tectonic events. Because the Mesozoic formations and the Hercynian basement on the graben flanks and inside the graben do not have the same evolution after uplift, our study includes 20 outcrops on both graben flanks and cores of the Soultz-sous-Forêts geothermal wells located inside the graben. The Hercynian granitic basement and Permo-Triassic formations were affected by several brittle phases associated with fluid circulation pulses related to graben formation during the Tertiary. We distinguished at least four stages: (1) reactivation of Hercynian structures associated with pre-rift tectonics during the early Eocene and descending meteoric waters, characterized by shearing/cataclasis textures and precipitation of illite and microquartz; (2) initiation of convective circulation of deep hot brines mixed with descending meteoric waters at the Hercynian basement/sedimentary cover interface during this first stage of Eocene rifting, characterized by dolomite and barite fillings in reactivated Hercynian fractures; (3) N-S tension fractures associated with rift tectonics just prior to uplift of the graben shoulders during Oligocene extension and descending meteoric waters, characterized by cataclastic textures and precipitation of quartz, illite, hematite, and barite; and (4) current convective circulation of deep hot brines mixed with descending meteoric waters at the Hercynian basement/sedimentary cover interface, characterized by calcite and barite fillings within the graben. This convective circulation is today present in deep geothermal wells in the western part of the Rhine graben.

First report of Phytophthora cinnamomi in forest stands in Germany

AbstractPhytophthora cinnamomi was repeatedly isolated from the rhizosphere of recently dead sweet chestnut trees in the upper Rhine valley. Identification was genetically confirmed by RFLP and sequencing of the ITS‐region. This is the first record of P. cinnamomi on forest land in Germany. Mode of introduction of this invasive species and potential factors favouring establishment are discussed.

Triaxial testing and hydraulic\u2013mechanical modeling of sandstone reservoir rock in the Upper Rhine Graben

The Upper Rhine Graben (URG) is a highly favorable location for deep geothermal energy utilization. One of the main reservoir horizons is the lower Triassic Buntsandstein formation. While quantification of thermal and hydraulic parameters and their coupling is common, geomechanical factors are often neglected due to high costs and the expense in gathering data. Equivalent experiments with analog rocks, like triaxial tests, can help to improve this knowledge. Triaxial tests have been performed and evaluated on two different Buntsandstein rock examples as analogs to quantify the mechanical behavior under stress conditions found in the Buntsandstein of the URG. Both samples, Tennenbach (TenSst) and Pfinztal (PfSst) Sandstone, show high Young’s moduli under axial loading. With confining pressures up to 90 MPa, the axial failure strength is up to 448 (TenSst) and 561 (PfSst) MPa. The results demonstrate the usability of linear elasticity for the expected stress range in the Buntsandstein reservoir of the URG. The deformation behavior is described and a linear failure criterion is derived, predicting failure strength with a high accuracy. These experimental results can be further employed as calibration parameters for a hydro-mechanical evaluation of the deformation processes.

Impact of rift dynamics on palaeoenvironmental conditions and hydrocarbon system development (northern Upper Rhine Graben, SW Germany)

The Upper Rhine Graben (URG), a classical hydrocarbon (HC) province, is part of the European Cenozoic Rift System. The rift graben development has led to a complex basin fill of terrestrial and marine Cenozoic deposits, providing several HC source and reservoir units. The aim of this study is the multidisciplinary analysis of the palaeoenvironmental conditions and source-rock development within the transgressive marine intervals, and the palaeothermal history of the graben system to improve the understanding of the HC system development. Palaeoenvironmental conditions are strongly influenced by rift-related tectonic activity. Transgressive marine intervals in times of major subsidence show high terrestrial input from the graben shoulders, leading to mainly terrigenous gas-prone kerogen, while transgressive marine intervals during weak tectonic activity are dominated by marine–brackish palaeoenvironments and oil-prone kerogen. This differs clearly from the previously suggested HC potential of these intervals. Thermal maturation analysis shows nearly constant maturation with depth, which is atypical for burial-controlled maturation. It indicates significant secondary thermal overprinting related to long-lasting very hot hydrothermal fluid systems, concentrated along fault zones. Therefore the development of the depositional setting, kerogen composition, thermal maturation and the HC potential is directly linked to the dynamics of the rift system development. Supplementary material: detailed results of all three wells are available at https://doi.org/10.6084/m9.figshare.c.4183106