Das Projekt "Subproject: The role of mantle plumes in the formation of Large Igneous Provinces: con-straints from noble gases" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum durchgeführt. Large igneous provinces (LIPs) are thought to have formed by magmatism resulting from decompressional melting of plume heads. Mantle plumes are upwellings of mantle material in focused conduits considered to originate from deep within the mantle. Plume heads are the leading ends of such upwellings. However, the evidence for this theory of LIP formation is mixed and has been challenged lately. In this context noble gas isotopes are important as a discriminator of deep-mantle origin because of the large and indicative isotope variations existing between the various terrestrial reservoirs. One of the main arguments for a plume origin of Continental Flood Basalt (CFB) magmas is excess 3He compared to MORB. High 3He/4He ratios have been found, e.g., in the Afar and Columbia River CFB provinces. Noble gas data from the Paraná-Etendeka LIP do not exist and the He isotope data available from the Tristan da Cunha hotspot are not meaningful. Thus we propose a noble gas study of samples from Tristan da Cunha, Etendeka and Paraná to constrain the mantle components involved in the formation of CFB and hotspot lavas and to shed some light on the role of plumes in LIP formation.
Das Projekt "Sub project: Imaging Induced Seismicity at the KTB" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Zentrum für Meeres- und Klimaforschung, Institut für Geophysik durchgeführt. The observation of naturally or artificially generated acoustic emissions (i.e., small earthquakes) by seismic networks is a powerful tool to image transport processes in the earth. During the injection experiments at the KTB a large number of events were observed. The precise spatio-temporal characterization of the seismic events is of utmost importance since all following interpretations (e.g., transport properties) rely entirely on this result. The localization of the events depends on the model used for the localization. The anisotropy of the KTB rocks is a well known feature but was not considered for the localization. Previous studies demonstrate that this leads to severe errors in the location of events. In this study we will first determine the anisotropic elastic features from the comprehensive KTB VSP data sets using 3-D anisotropic tomography for P- and S-waves. This step is essential for the localization. The obtained tomographic anisotropic 3-D model will then be used for the localization of the acoustic emissions of the 2000 and 2004 injection experiments. A newly developed technology based on reversed modelling or time reversed acoustic mirrors will be used to image the events. This techniques does not require picking of events and increases the detection level of the network owing to the stacking character of the method and allows to locate arrivals not visible in the individual seismograms of the network.
Das Projekt "Sub project: Hydrochemical and hydraulic properties of the continental upper crust at the KTB site" wird vom Umweltbundesamt gefördert und von Regierungspräsidium Freiburg, Abteilung 9 - Landesamt für Geologie, Rohstoffe und Bergbau durchgeführt. A constant rate pumping test of one year duration is planed to be carried out in the 4.0 km deep pilot hole of KTB. Watertable fluctuations in the pilot borehole and in the 9.1 km deep main borehole will be monitored as well. A wealth of data (pumping rate, watertable/ pressure, temperature, salinity/electrical conductivity, water samples,....) will become available, some even online. The first objective of the proposed project is to determine the flow system (type of aquifer model). From this deduced hydraulic model follow the hydraulic characteristics (such as: transmissivity, storage coefficient, fracture lengt/ width/aperture, permeability of fractures and matrix,....) describing the properties of the crystalline basement rocks in vicinity of the KTB pilot- and main hole. The length of the expect test radius is some 1000 m. The proposed project intends also to determine the degree of the hydraulic connection between the two holes (having a depth difference of 5.1 km). Additional information, such as water analyses, will be needed in interpreting the hydraulic data. A second major objective is the modelling of water-rock interaction (WRI) processes using the chemical data of KTB fluids. In particular the time series of chemical data will be used to model the kinetic and time dependent processes. We expect as well to see some breakthroughs of 'fresh, clean' crystalline basement water and another breakthrough resulting from fluid stored in the main hole and its surrounding.
Das Projekt "Sub project: The Mid-Miocene 'Monterey Event': A global productivity increase?" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Fachbereich Geowissenschaften, Institut für Geologie durchgeführt. We investigate the Mid-Miocene 'Monterey Event' (Vincent and Berger, 1985), a positive carbon isotope excursion of 4.5 my duration, in order to contribute to a better understanding of the processes that control the distribution of carbon in the terrestrial, atmospheric and marine reservoirs. This delta 13C excursion during a period of extreme warmth has been attributed to the enhanced sequestration of organic carbon in the margins of the northern Pacific ocean (op.cit.). We aim to clarify whether pelagic sediments also reflect increased productivity that might have contributed to the delta 13C shift. If this is the case, we further aim to identify the sources of nutrients responsible for a 4.5 m.y. period of globally increased productivity. Finally, we aim to investigate if productivity variations can be related to pCO2atm variations (as proposed by Pagani et al.(1999)), by means of delta 13C analyses of bulk marine organic matter in our samples by D. Groecke (fractionation between delta 13Ccarb and delta 13Corg).
Das Projekt "Extreme events in the past and future - A comparative assessment for the Hai He river and the Poyang lake basins" wird vom Umweltbundesamt gefördert und von Rheinische Friedrich-Wilhelms-Universität Bonn, Meteorologisches Institut durchgeführt. The impact of future climate change on land-use and water resource management is strongly dependent on the related changes in weather extremes. The future can only be assessed by the use of global climate models, which currently lack the necessary spatial resolution to represent such events. Moreover, global climate models are not able to incorporate all processes leading to extremes because of their low resolution. Thus downscaling of such runs is necessary, and only dynamical downscaling with high-resolution regional models is able to catch the necessary non-linear processes and process chains leading to extremes. The goal of this joint proposal is to provide estimates including their uncertainties of the behaviour of extreme weather events impacting land-use and water management for the 21st century for two climatically very different catchments, namely the Hai He river and the Poyang lake basins. To this goal we will first analyse the past of extreme events in both regions on the basis of observations and reanalysis data sets using state of the art extreme value statistics. Dynamical downscaling of global climate runs will be performed in order to evaluate the future of extreme events in the catchments. This necessitates first an evaluation of simulations of the current climate and its extremes by comparison with observations on a statistical basis. This will enable us to use the most appropriate regional climate model and to select the parametrisation setup most suitable for both regions, which might be different. While the Chinese partners will provide the observation data sets and perform the dynamical downscaling of global climate runs, the German partners will install the dynamical downscaling procedure at the Chinese partner institute, and generate the statistics of extremes both from observations and the simulations. The evaluation towards trends and uncertainties will be performed in close cooperation.
Das Projekt "Sub project: Fault zone damage and chemical reactions at depth in the San Andreas Fault Zone: A study of SAFOD drill core samples" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum durchgeführt. The results of the first funding period, particularly the proof of several weakening and hardening mechanisms operating in the fault gouge of four SAFOD core samples (e.g. amorphous material, nano-scale pore spaces, dissolution-precipitation processes, intracrystalline plasticity) inspired a more detailed study of microstructures in order to specify the cause of mechanical weakness along the San Andreas Fault (SAF). Therefore we applied for and received four additional core samples from different depths and different distances to the fault contact. In particular, we will focus on: - The analysis of dominant microstructures in the new SAFOD samples. Based on our previous experience we will predominantly use the transmission electron microscopy (TEM). These studies have proven to be the most powerful tool for analyzing microstructures. The cutting of foils with the focused ion beam technique (FIB) allows identifying microstructures down to the nm scale without damage. - The observed microstructures will be interpreted in view of their implication for fault weakening mechanisms integrating previous results of the core samples from the first funding period. - The observed agglomeration of flocculated clay particles in previous samples calls for further detailed TEM investigations of clay minerals. - Some vein-calcites show evidence for intense intracrystalline plasticity (deformation twins and dislocation creep). We will measure dislocation and twin densities in calcite veins in the new sample set. The results will be used for stress estimations based on paleo-piezometric relationships. - First results of stable isotope analyses of vein calcites provide indications that the fluids were dominantly derived from deeper sources. We will further analyze stable isotopes with the aim to characterize the origin of fluids penetrating the fault gouge. - Mercury porosimetry and the BET gas adsorption methods will be used to measure the connected rock porosity pore volume and pore surface areas of our new samples. Porosity data will be used to roughly estimate permeability. - SAFOD microstructures will be compared to samples recently obtained from the Taiwan Chelungpu fault Drilling Project (TCDP).
Das Projekt "Sub project: The mobilisation of Platinum-Group Elements in altered oceanic crust from ODP-borehole 1256D for tracing the noble metal flux in the crust" wird vom Umweltbundesamt gefördert und von Karlsruher Institut für Technologie (KIT), Institut für Angewandte Geowissenschaften, Abteilung Mineralogie und Petrologie durchgeführt. Mafic volcanic rocks of different tectonic settings display a wide range of Pt/Pd-ratios lower than that of the primitive mantle (PM) which cannot be accounted for by known partition coefficients of Pd and Pt between sulphide melt and silicate melt. Various processes have been invoked to explain this observation, including hydrothermal rock/water interactions or serpentinisation. However, so far no study has systematically investigated the effects of hydrothermal alteration on the PGE budget for example on a complete section of altered upper oceanic crust. Hence, little is known on Pt-Pd fractionation during alteration. We propose to fill this gap by studying a complete profile of altered upper oceanic crust and the uppermost gabbroic section, formed at the East Pacific Rise some 15 Ma ago and drilled at the multicruise ODP-borehole 1256D (Wilson et al., 2006). Combined measurements of platinum-group elements (PGE) and Cu-Sisotopes in key pool samples, shared with other shipboard party members, will help to evaluate PGE mobility during alteration and to study quantitatively the fractionation behaviour of Pt and Pd along the hydrothermal fluid path in the oceanic crust. These insights are highly relevant for understanding ore forming processes in the oceanic crust, since large PGE deposits are related to mafic volcanism (i.e. Norils'k).
Das Projekt "Long-term Driving Factors & Land Use Policies in Europe" wird vom Umweltbundesamt gefördert und von Forstliche Versuchs- und Forschungsanstalt Baden-Württemberg durchgeführt. The basic and unifying question of this project is to what extent and how ecosystems maintain their resilience towards the different impacting factors (i.e. climate change). This again impinges on biodiversity conservation strategies. Of special interest hereby is how different/similar ecosystems and species react in different vegetation zones and eco-regions under different climatic conditions and disturbance/driving factors? What are the thresholds of the resilience of ecosystems under increasing temperatures due to climatic change, and what will be the response of communities that have not experienced such disturbances in the past? This project will cover the whole northern boreal region using pristine Russian forests as a reference. It would provide a careful evaluation of this long geographical, political and historical gradient of different land-use politics and their biodiversity effects from Russia via the Baltic countries to central Europa. This would be helpful in understanding and predicting the future changes and choosing management strategies. Although there is a great deal of interest in the biological diversity in species/ecosystem and genetic level, it is only recently that researchers have started to investigate the processes that exert parallel influences on these different levels of biodiversity. Policy aimed at conserving biodiversity has focused on species diversity. Loss of genetic diversity, however, can affect population resistance, evolutionary genetic potential, and population fitness. Species diversity and genetic diversity may be correlated as a result of processes acting in parallel at the two levels. However, no intensive studies have been conducted so far to predict the conditions under which different relationships between species diversity and genetic diversity might arise and therefore when one level of diversity may be predicted using the other. In this project all these levels of biodiversity will be included in a interdisciplinated study. This project will address the integration of data depicting long-term landscape history with present day data (such as statistical, GIS and Remote Sensing data, etc.) and models predicting future developments.
Das Projekt "Phosphorus transport along soil pathways in forested catchments" wird vom Umweltbundesamt gefördert und von Technische Universität Dresden, Institut für Bodenkunde und Standortslehre durchgeführt. Phosphorus (P) is an essential nutrient for living organisms. Whereas agriculture avoids P-limitation of primary production through continuous application of P fertilizers, forest ecosystems have developed highly efficient strategies to adapt to low P supply. A main hypothesis of the SPP 1685 is that P depletion of soils drives forest ecosystems from P acquiring system (efficient mobilization of P from the mineral phase) to P recycling systems (highly efficient cycling of P). Regarding P fluxes in soils and from soil to streamwater, this leads to the assumption that recycling systems may have developed strategies to minimize P losses. Further, not only the quantity but also the chemistry (P forms) of transported or accumulated P will differ between the ecosystems. In our project, we will therefore experimentally test the relevance of the two contrasting hypothetical nutritional strategies for P transport processes through the soil and into streamwater. As transport processes will occur especially during heavy rainfall events, when preferential flow pathways (PFPs) are connected, we will focus on identifying those subsurface transport paths. The chemical P fractionation in PFPs will be analyzed to draw conclusions on P accumulation and transport mechanism in soils differing in their availability of mineral bound P (SPP core sites). The second approach is an intensive streamwater monitoring to detect P losses from soil to water. The understanding of P transport processes and P fluxes at small catchment scale is fundamental for estimating the P exports of forest soils into streams. With a hydrological model we will simulate soil water fluxes and estimate P export fluxes for the different ecosystems based on these simulations.
Das Projekt "Sub project: Seismic site characterization in and around the COSC-1 drillhole" wird vom Umweltbundesamt gefördert und von Technische Universität (TU) Bergakademie Freiberg, Institut für Geophysik und Geoinformatik durchgeführt. The project COSC (Collisional Orogeny in the Scandinavian Caledonides) focuses on the mid Paleozoic Caledonide Orogen in Scandinavia in order to better understand orogenic processes, both in the past and in recent active mountain belts (Gee et al., 2010). The Scandinavian Caledonides provide a well preserved example of Paleozoic plate collision, where the surface geology in combination with geophysical data provide control of the geometry of the Caledonian structure, both of the allochthon and the underlying autochthon, including a shallow W-dipping décollement surface on a thin skin of Cambrian black shales beneath the Caledonian thrust sheets. The structure of the basement underneath the décollement is highly reflective and apparently dominated by mafic sheets intruded into either late Paleoproterozoic granites or Mesoproterozoic volcanics and sandstones. The COSC project will examine the structure and physical conditions of these units, in particular the Caledonian nappes ('hot' allochthon) and the underlying basement, with two approximately 2.5 km deep drillholes, located near Åre and Mörsil in western Jämtland (http://www.sddp.se/COSC). In addition to that, the drillholes will provide unique information about the present temperature gradient in the Caledonides, the porosity and permeability of the rock formations, and the petrophysical properties of the rocks at depth. Existing regional seismic and magnetotelluric data have imaged the geometry of the upper crust, and pre-site seismic reflection survey were preformed in 2010 and 2011 to better define the exact drill site locations (Hedin et al., 2012). This present proposal is dedicated to complement these surface seismic measurements by drillhole-based investigations to better resolve and define the small-scale structures (including lithological boundaries, steeply dipping fault segments, fracture sets, etc.) around the drillhole COSC-1. This will be achieved by a combination of seismic transmission and reflection experiments using a 3C borehole geophone system and complemented by 3C geophones at the surface, where sources and surface receivers will be aligned at different azimuths and centred around the borehole location. The data processing will employ recently developed advanced imaging techniques and will focus on, amongst other things, the analysis of anisotropic effects caused by aligned fractures and faults and their relation to the stress regime. The results of our investigations will be high-resolution images of the fine-scale structure of faults and fractures around the borehole. This information is vital not only for a reliable spatial extrapolation of the structural and petrophysical properties observed in the borehole, but also for a thorough understanding of the tectonic and geodynamic setting, including, but not limited to, the past and present stress regime.
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