Burschil T.,Leibniz Institute for Applied Geophysics |
Scheer W.,Geological Survey of Germany |
Kirsch R.,Geological Survey of Germany |
Wiederhold H.,Leibniz Institute for Applied Geophysics
Hydrology and Earth System Sciences | Year: 2012
Within the scope of climatic change and associated sea level rise, coastal aquifers are endangered and are becoming more a focus of research to ensure the future water supply in coastal areas. For groundwater modelling a good understanding of the geological/hydrogeological situation and the aquifer behavior is necessary. In preparation of groundwater modelling and assessment of climate change impacts on coastal water resources, we setup a geological/hydrogeological model for the North Sea Island of Föhr.
Data from different geophysical methods applied from the air, the surface and in boreholes contribute to the 3-D model, e.g. airborne electromagnetics (SkyTEM) for spatial mapping the resistivity of the entire island, seismic reflections for detailed cross-sections in the groundwater catchment area, and geophysical borehole logging for calibration of these measurements. An iterative and integrated evaluation of the results from the different geophysical methods contributes to reliable data as input for the 3-D model covering the whole island and not just the well fields.
The complex subsurface structure of the island is revealed. The local waterworks use a freshwater body embedded in saline groundwater. Several glaciations reordered the youngest Tertiary and Quaternary sediments by glaciotectonic thrust faulting, as well as incision and refill of glacial valleys. Both subsurface structures have a strong impact on the distribution of freshwater-bearing aquifers. A digital geological 3-D model reproduces the hydrogeological structure of the island as a base for a groundwater model. In the course of the data interpretation, we deliver a basis for rock identification.
We demonstrate that geophysical investigation provide petrophysical parameters and improve the understanding of the subsurface and the groundwater system. The main benefit of our work is that the successful combination of electromagnetic, seismic and borehole data reveals the complex geology of a glacially-affected island. A sound understanding of the subsurface structure and the compilation of a 3-D model is imperative and the basis for a groundwater flow model to predict climate change effects on future water resources. © 2012 Author(s).
Dutta S.,Indian Institute of Technology Bombay |
Hartkopf-Froder C.,Geological Survey of Germany |
Witte K.,FH Aachen |
Brocke R.,Senckenberg Institute |
Mann U.,Jülich Research Center
International Journal of Coal Geology | Year: 2013
Transmission micro-FTIR spectroscopy has been conducted to elucidate the macromolecular structure of well-preserved fossil palynomorphs including prasinophycean algae, megaspores, chitinozoans, and scolecodonts. Plant and arthropod cuticles which may be present in palynological residues have also been investigated. Important differences are noted among these palynomorph groups regarding the intensities of CHx, CO and aromatic CC absorptions. Tasmanites, Leiosphaeridia, and plant cuticles are characterized by stronger aliphatic CHx stretching (3000-2800cm-1), strong CH3 (1460-1450cm-1), and intense CO group (1710-1700cm-1) absorptions. Aromatic CC stretching (1610-1560cm-1) absorptions are less intense and aromatic CH out of plane (900-750cm-1) absorptions are absent. In contrast, chitinozoans, scolecodonts, and arthropod cuticles show intense aromatic CC stretching (1620-1560cm-1) and aromatic CH out of plane (900-750cm-1) absorptions. Aliphatic CHx stretching (3000-2800cm-1) and CO group (1710-1700cm-1) absorptions are less intense. Megaspores are characterized by stronger aliphatic CHx stretching (3000-2800cm-1), strong CH3 (1460-1450cm-1), and moderate aromatic CC stretching (1610-1560cm-1) and CO group (1710-1700cm-1) absorptions. The CH2/CH3 intensity ratio has been used to assess the relative chain length and degree of branching. The aliphatic components in Tasmanites, Leiosphaeridia, and plant cuticles are longest chained and least branched whereas those in chitinozoans, scolecodonts, and arthropod cuticles are shortest chained and most branched. Megaspores show intermediate CH2/CH3 ratio. The present study demonstrates that palynomorphs differ in functional group chemistry and this spectroscopic technique can be useful to assign biological affinity of enigmatic palynomorphs. Furthermore, micro-FTIR spectroscopy provides insights into the hydrocarbon generating potential of different fossil palynomorph groups. © 2013 Elsevier B.V.
Salamon M.,Geological Survey of Germany |
Konigshof P.,Senckenberg Institute
Gondwana Research | Year: 2010
The Rheinisches Schiefergebirge in the Rheno-Hercynian zone of the mid-European Variscides was geographically situated on Laurussia's southern shelf during the Devonian. In its eastern part (Lahn-Dill area), Givetian coarse clastic sediments, formerly misinterpreted as transgressional conglomerates, are recognised as olistostrome deposits intercalated in basinal sediments that document a phase of rifting on the southern shelf of Laurussia. The clastic components, redeposited as olistolithes and rounded boulders, are locally derived rocks of Emsian and Givetian age. The olistostromes show facies patterns comparable with other syn-rift deposits. The proximal facies is characterised by olistolithes and slideflow debrites, overlain by debrites and intercalated with turbidites. The distal facies is represented by intercalation of debrites and turbidites. Both grade upwards into basinal sedimentation. Based on conodont stratigraphy, the redeposition lasted from the Middle varcus Zone to the disparilis Zone. During the Middle varcus Zone footwall uplift raised the sedimentary column of the source area by about 500 m above, which brought it above sea level. Rifting of the Laurussian shelf as a result of hinterland transtension and extension caused by the oblique collision of Peri-Gondwana with Laurussia provides the most plausible explanation for the development of the olistostromes, olistolithes and slideflow debrites in the eastern Rheinisches Schiefergebirge. © 2009 Elsevier B.V. All rights reserved.
Lehmann K.,Geological Survey of Germany
Journal of Applied Geophysics | Year: 2010
Correction concepts for the elimination of environmental influences on gamma-ray logs have been published in a number of articles and in guidelines by service companies. However, these widely-used processing rules for open- and cased-hole measurement conditions have been presented in different forms using different assumptions. For a detailed comparison, these concepts were reduced to simple analytical formula with the application of the same units and scaling to common, standardised conditions. For geological and technical drilling, environmental influences like borehole geometry, casing configuration and material, as well as mud density have turned out to represent the most important effects for a characterisation of environmental conditions. Typical case histories show that correction processing may lead to differing results, depending on the chosen presumptions. A thorough analysis of different types of influences and a careful choice of adequate correction procedures substantially improve the quality of gamma-ray log data. Further implications of these analytical correction rules permit also the quantitative interpretation of logs in dry cased-hole intervals and with the presence of tool joints or casing collars. The latter effect is widely underrated but is proven here to be a necessary step in precise gamma-ray log processing. © 2009 Elsevier B.V. All rights reserved.
Bocker J.,RWTH Aachen |
Littke R.,RWTH Aachen |
Hartkopf-Froder C.,Geological Survey of Germany |
Jasper K.,Helmholtz Center Potsdam |
Schwarzbauer J.,RWTH Aachen
International Journal of Coal Geology | Year: 2013
The molecular composition of 58 Duckmantian Ruhr coals and adjacent sedimentary rocks has been analyzed using organic-geochemical investigations representing a maturity range from 0.74 to 0.98% vitrinite reflectance. In addition eight samples of higher maturity (1.46 to 3.55% vitrinite reflectance) were studied for comparison. The composition of coals depends primarily on plant input into the peat swamps, but also to a large extent on thermal maturity. Several maturity-related parameters have been applied in this study such as MPI, DMAI, and diverse hopanoid-based maturity ratios. Especially diamantane-based parameters proved to be excellent for characterizing high rank samples, whereas hopane- and phenanthrene-based parameters are well-suited for the lower maturity range. Various specific biomarkers reflect the composition of the Duckmantian coals concerning the floral differences and floral shift during the Westphalian. The dominating n-alkanes, hopanes, and bicyclic sesquiterpanes show only marginal differences and reveal a quite homogenous floral composition within the six coal seams. Tetracyclic diterpanes, as approved markers for modern as well as Paleozoic conifers and "pre-gymnosperms", have been identified in all six coal seams, but in low concentration (one order of magnitude lower than bicyclic sesquiterpanes). A slight increase of the tetracyclic diterpane ent-beyerane in the younger seams indicates an increase in abundance of "pre-gymnosperms" (cordaites) during the Duckmantian. Significantly increased proportions of diverse compounds like bicyclic sesquiterpanes (eudesmane) or tetracyclic terpanes clearly testify an origin from higher land plants. The major part of the Duckmantian coal swamps biomass with its vitrinite rich coals originated presumably from barks of arborescent lycopods. High concentrations of hopanes mirror the input of bacterial organic matter and a strong microbial reworking of the deposited terrestrial plant organic matter. © 2012 Elsevier B.V.
Diepolder G.W.,Geological Survey of Germany |
Pamer R.,Geological Survey of Germany
Rendiconti Online Societa Geologica Italiana | Year: 2014
The Alpine Foreland Basins bear a multitude of natural subsurface resources (geopotentials) which can contribute substantially to boost green energy. Sustainable planning and management of geopotentials requires a holistic, transnational and three-dimensional evaluation of the geological fundamentals. Facing different data availability and policy in the Geological Survey Organizations (GSOs) in charge, transnational collaboration calls for a maximum of coordination from the very beginning of the data preparation and the 3D modeling processes, based on concerted proceedings and best practice in seismic processing and interpretation, 3D modeling and geopotential assessment, and demands a geo data infrastructure for full interoperability among the partners and the dissemination of seamless results. This article outlines the objectives and scope of the GeoMol project and summarizes the state of the art of its achievements to provide cross-border harmonized information via a web accessible exchange and information system. © Società Geologica Italiana, Roma 2014.
Ebel B.A.,Geological Survey of Germany
Vadose Zone Journal | Year: 2012
Wildfire is one of the most significant disturbances in mountainous landscapes and can affect soil temperature, which can in turn impact ecologic and geomorphologic processes. This study measured the temperature in near-surface soil (i.e., top 30 cm) during the first summer after a wildfire. In mountainous environments, aspect can also affect soil temperature so north- vs. south-facing aspects were compared using a fully factorial experimental design to explore the effects of both wildfire and aspect on soil temperature. The data showed major wildfire impacts on soil temperatures on north-facing aspects (unburned ~4-5°C cooler, on average) but little impact on south-facing aspects. Differences in soil temperatures between north-facing and south-facing unburned aspects (north ~5°C cooler, on average) were also observed. The data led to the conclusion that, for this field site during the summer period, the forest canopy and litter and dufflayers on north-facing slopes (when unburned) substantially decreased mean soil temperatures and temperature variability. The sparse trees on south-facing slopes caused little to no difference in soil temperatures following wildfire in south-facing soils for unburned compared with burned conditions. The results indicate that wildfire can reduce or even remove aspect impacts on soil temperature by combusting the forest canopy and litter and dufflayers, which then homogenizes soil temperatures across the landscape. © Soil Science Society of America.
Jasper K.,RWTH Aachen |
Hartkopf-Froder C.,Geological Survey of Germany |
Flajs G.,RWTH Aachen |
Littke R.,RWTH Aachen
International Journal of Coal Geology | Year: 2010
This study focuses on the reconstruction of the environment during peat swamp development. Eight coal and sedimentary organic rock bearing seam successions were examined all belonging to the Duckmantian (Pennsylvanian, Late Carboniferous). 410 samples were analysed with coal petrographical methods, 155 of these also by palynological methods. In addition, on 55 samples organic geochemical investigations were carried out with respect to n-alkanes and iso-alkanes. The established coal petrographical parameters gelification index (GI), tissue preservation index (TPI), groundwater index (GWI) and vegetation index (VI) were used to characterize different periods of peat swamp development. Furthermore, the new index WCI (= Water Cover Index) was introduced to reflect water level conditions by using the ratio between hydrophilous/hygrophilous and mesophilous plants. In this study the index is based on palynological data but can be equally applied when quantitative macrofloral counts are available. GI versus TPI values show two general trends of peat swamp evolution: low GI and TPI values as indicator for drier swamp conditions like ombrogenous mires and high GI and TPI values which show a trend to water covered environments like topogenous mires. In addition, ash yields and GWI versus VI data also emphasize a general trend from topogenous to ombrogenous mires. A decrease in water level towards the top of the seams and thus resulting in the development of domed mires is reflected by the newly introduced WCI. Hence, these parameters show recurrent peat swamp successions, characterized by mineral- and vitrinite-rich coals, typical for topogenous swamps and an evolution towards inertinite/liptinite-rich coals with low ash yield, typical for ombrogenous swamps.n-alkane ratios like the carbon preference index (CPI), pristane/n-C 17, phytane/n-C 18, pristane/phytane and the n-C 17/n-C 27 relationship indicate a strong correlation of these parameters with thermal maturity, e.g. CPI values correlate with vitrinite reflectance. Sulphur/organic carbon (S/TOC) ratios are quite uniform in clastic rocks with low to moderate TOC contents, but highly variable in coals, probably reflecting variable sulphate availability during deposition of peats. Sphenophyll-rich floral assemblages are restricted to low sulphur environments. © 2010 Elsevier B.V.
Banning A.,RWTH Aachen |
Rude T.R.,RWTH Aachen |
Dolling B.,Geological Survey of Germany
Journal of Hazardous Materials | Year: 2013
Cretaceous shallow marine sediments from northwestern Germany exhibit a distinct colour and geochemical boundary in a depth of several decametres, witnessing a terrestrial oxidative paleo redox process which resulted in cement loss and oxidation of Fe(II) phases. Sediment samples were obtained from boreholes drilled in near-coastal and further basinward paleo environments, including both reduced and oxidized redox facies, to characterize As and Fe occurrence in unaltered layers and redistributional consequences of the redox event. Geochemical and mineralogical composition and As fractionation were assessed. Arsenic resides in pyrite in the reduced section with a bulk rock maximum concentration of 39μgg-1, calculated Aspyrite is ~0.2wt.%. Siderite concretions in the fine sands do not function as As sinks, neither does glauconite whose general As/Fe leaching behaviour was characterized. In the zone of redox transition, reduced and oxidized phases coexist and elevated As concentrations (up to 73μgg-1) with high proportions of reactive As were detected. Arsenic behaviour changes from relatively homogeneous Fe sulphide-control in the unaltered sediments to very heterogeneous Fe hydroxide-control above the paleo redox boundary. The studied characteristics determine recent As availability in the subsurface and must be considered during groundwater extraction from this highly important aquifer. © 2012 Elsevier B.V.
Dustira A.M.,University of Tromsø |
Wignall P.B.,University of Leeds |
Joachimski M.,Friedrich - Alexander - University, Erlangen - Nuremberg |
Blomeier D.,Norwegian Polar Institute |
And 2 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2013
The Permian-Triassic extinction event is considered to be the most devastating environmental crisis of the Phanerozoic. With many coinciding factors involved, the role of marine anoxia during the extinction is still poorly understood. In this study a boreal Permian-Triassic Boundary (PTB) section from Svalbard, Norway has been investigated with the aim of better understanding the timing and nature of local marine anoxia onset and extinction events across the PTB. The section comprises the Kapp Starostin and Vikinghøgda formations; δ13Corg values indicate the PTB is located within the lower part of the Vikinghøgda Formation. Lag deposits at the top of the Kapp Starostin Formation indicate a marine hiatus and ensuing transgression during the Late Permian shortly before the extinction event, implying concurrence of major ecological changes and sea-level rise. Pyrite framboid size distributions and total organic carbon (TOC) were used to evaluate bottom water oxygen conditions, and show that changes in bottom water redox conditions and extinction are clearly linked. Oxic to dysoxic bottom water conditions prevailed during deposition of Kapp Starostin Formation sediments and changed to anoxic to euxinic conditions above the formation boundary. The onset of anoxia is not abrupt but rather shows a gradual increase within the Kapp Starostin Formation during the Late Permian. The tipping point where bottom waters reach a long-term state of anoxia to euxinia coincides with the final extinction event, though changes in biotic assemblages at the top of the Kapp Starostin Formation indicate a marine ecosystem crisis prior to this. Oxygen depletion in the boreal region, as seen in our study section and correlating to Greenland and Arctic Canada, seems to be consistently more severe than in lower latitude settings. © 2013 Elsevier B.V.