ALBERT

Description: Magmatic-hydrothermal systems form a variety of ore deposits at different proximities to upper-crustal hydrous magma chambers, ranging from greisenization in the roof zone of the intrusion, porphyry mineralization at intermediate depths to epithermal vein deposits near the surface. The physical transport processes and chemical precipitation mechanisms vary between deposit types and are often still debated. For this study, we investigate the fluid evolution from proximal to distal settings at the Pirquitas and Chinchillas Mines in NW Argentina and the Sweet Home Mine, Colorado. New results from fluid inclusion and isotopic analyses indicate a contribution of magmatic fluids in the formation of the SnAg Pirquitas Mine, even though no direct association to a magmatic intrusion is visible. Therefore, this deposit may represent a rather distal setting. In contrast, the Ag-Pb-Zn Chinchillas Mine is hosted in volcanic extrusive units and is directly associated to an underlying dacite diatreme. In that respect, this deposit is proximal to a volcanic complex, but due to its shallow emplacement is distal to an inferred magmatic intrusion at depth. The Ag-polymetallic Sweet Home Mine (currently mined for gemmy rhodochrosite) is related to an assumed hidden Mo porphyry, but may be located more proximal to a magmatic intrusion as compared to the other deposits. Performing fluid inclusion analysis, Raman spectroscopy, noble gas isotopic compositions and LA-ICPMS measurements as well as the analysis of stable (H, O, S) and radiogenic (Pb, Sr) isotopic compositions, we aim to reconstruct the evolution and P-T-x properties of the ore-forming fluids in the respective ore deposits. As all studied deposits are characterized by a distinct sulfide mineralization stage, we also investigate whether this stage has formed by mixing of magmatic fluids with variable amounts of externally derived fluids. Furthermore, numerical modelling of the transition from a porphyry to an epithermal environment, considering country rock permeability, fluid pressure distribution, fluid temperatures, and varying locations of the magmatic plume, is used to build a quantitative model for the formation of these types of epithermal deposits.

Description: Microbial decomposition of thawed permafrost carbon in thermokarst lakes leads to the release of ancient carbon as the greenhouse gas methane (CH4), yet potential mitigating processes are not understood. Here, we report δ 13C–CH4 signatures in the pore water of a thermokarst lake sediment core that points towards in situ occurrence of anaerobic oxidation of methane (AOM). Analysis of the microbial communities showed a natural enrichment in CH4-oxidizing archaeal communities that occur in sediment horizons at temperatures near 0 °C. These archaea also showed high rates of AOM in laboratory incubations. Calculation of the stable isotopes suggests that 41 to 83% of in situ dissolved CH4 is consumed anaerobically. Quantification of functional genes (mcrA) for anaerobic methanotrophic communities revealed up to 6.7 ± 0.7 × 105 copy numbers g−1 wet weight and showed similar abundances to bacterial 16S rRNA gene sequences in the sediment layers with the highest AOM rates. We conclude that these AOM communities are fueled by CH4 produced from permafrost organic matter degradation in the underlying sediments that represent the radially expanding permafrost thaw front beneath the lake. If these communities are widespread in thermokarst environments, they could have a major mitigating effect on the global CH4 emissions.

Description: Satellite laser ranging (SLR) constitutes a fundamental space geodetic technique providing global geodetic parameters, such as geocenter coordinates, Earth rotation parameters, and low-degree gravity field coefficients. The tropospheric delay correction is one of the crucial corrections that have to be taken into account when processing SLR data. Current conventional models of the troposphere delays assume a full symmetry of the atmosphere above SLR stations. Neglecting horizontal gradients in SLR solutions introduces a systematic error in SLR products, especially for the observations at low elevation angles, and leads to a deterioration of the consistency between SLR and other space geodetic techniques, such as global navigational satellite systems and very-long-baseline interferometry. We derive new mapping function coefficients, as well as first- and second-order horizontal gradients, all of which are based on numerical weather models, in order to properly consider the azimuthal asymmetry in SLR solutions. We test the enhanced mapping function and horizontal gradients on the solutions based on 11 years of SLR observations to LAGEOS-1/2 satellites and 1 year of SLR observations to Sentinel-3A. The consideration of azimuthal asymmetry of the atmosphere above the SLR stations has a systematic effect on SLR-derived products, such as station and geocenter coordinates and pole coordinates. Horizontal gradients in SLR solutions improve the consistency between SLR-derived pole coordinates and the combined IERS-C04 series by means of reducing the offset for the X and Y pole coordinates by 20 μas. The second-order horizontal gradients are negligible in SLR solutions; thus, including first-order gradients is sufficient for SLR solutions.

Description: At extensional volcanic arcs, faulting often acts to localize magmatism. Santorini is located on the extended continental crust of the Aegean microplate and is one of the most active volcanoes of the Hellenic arc, but the relationship between tectonism and magmatism remains poorly constrained. As part of the Plumbing Reservoirs Of The Earth Under Santorini experiment, seismic data were acquired across the Santorini caldera and the surrounding region using a dense amphibious array of 〉14,300 marine sound sources and 156 short‐period seismometers, covering an area 120 km by 45 km. Here a P wave velocity model of the shallow, upper‐crustal structure (〈3‐km depth), obtained using travel time tomography, is used to delineate fault zones, sedimentary basins, and tectono‐magmatic lineaments. Our interpretation of tectonic boundaries and regional faults are consistent with prior geophysical studies, including the location of basin margins and E‐W oriented basement faults within the Christiana Basin west of Santorini. Reduced seismic velocities within the basement east of Santorini, near the Anydros and Anafi Basins, are coincident with a region of extensive NE‐SW faulting and active seismicity. The structural differences between the eastern and western sides of Santorini are in agreement with previously proposed models of regional tectonic evolution. Additionally, we find that regional magmatism has been localized in NE‐SW trending basin‐like structures that connect the Christiana, Santorini, and Kolumbo volcanic centers. At Santorini itself, we find that magmatism has been localized along NE‐SW trending lineaments that are subparallel to dikes, active faults, and regional volcanic chains. These results show strong interaction between magmatism and active deformation.

Description: Power-to-Gas (PtG) is a chemical energy storage technology that converts electrical energy into a high-energy density combustible gas. This technology alleviates the contradiction between power supply and demand due to the intermittent electricity production from environment-friendly renewable energy. Hydrogen (H2), produced by electrolysis, can be used to produce synthetic methane (CH4) by reacting with carbon dioxide (CO2) that is captured from carbon emission sources. Subsurface gas storage is one of the most important processes in a PtG system. However, nearly a half of the total stored gas is used as cushion gas to maintain a suitable reservoir pressure, indicating large amounts of CH4 might be wasted and trapped in geological formations. Based on a PtG system, CO2 can be a promising choice as a cushion gas due to its high effective compressibility near its critical conditions. In this paper, a numerical model is established based on the theory of the fluid flow and molecular diffusion to study the role of CO2 as a cushion gas in increasing the gas storage capacity. The accuracy of this model is verified by comparing with that of Curtis M. Oldenburg. However, because of the declining purity of recovered gas induced by the convection and diffusion of two kinds of gases in the same reservoir. The influences of reservoir thickness on the distribution of mixed region are discussed. The results show that thicker reservoir would be a better choice for the geological storage of CH4 with CO2 as a cushion gas.

Description: The migrating fluid-mineral interface provides an opportunity for the uptake of trace elements as solid solutions in the newly formed crystal lattice during the non-equilibrium growth of the crystal. However, mineral nanoparticles could precipitate directly from the interfacial fluid when it evolves to a supersaturated situation. To better understand the role of mineral nanoparticles in this scenario, this study focuses on a well-documented magnetite with oscillatory zoning from a skarn deposit by using high-resolution transmission electron microscopy (TEM). Our results show that the Al concentration in magnetite measured on a micrometer-scale is caused by three different effects: Al solid solution, Al-rich nanometer-sized lamellae, and zinc spinel nanoparticles in the host magnetite. Here, we propose a genetic relationship among the three different phases mentioned above. At first, a continuous increase of the Al concentration in the interfacial fluid can be incorporated into the crystal lattice of magnetite forming a solid solution. During cooling in a later stage, aluminum in magnetite is oversaturated and exsolution of hercynite (Al-rich lamellae) occurs from the host magnetite. If the Al concentration at the fluid-magnetite interface still increases during further growth of magnetite, the substitution of Fe by Al has gradually reached saturation so that aluminum cannot be incorporated in the magnetite crystal structure any longer. Using the magnetite lattice as a template, nucleation of abundant zinc spinel nanoparticles occurs. This will, in turn, lead to a gradual depletion of Al concentration in the interfacial fluid until the available ions for zinc spinel nucleation and growth have been used up. As a result, the migrating fluid-magnetite interface will enrich the Al concentration in the interfacial fluid until the available ion concentration is sufficient for nucleation of zinc spinel phase again. The fluid-mineral interface in this mechanism has been repeatedly utilized during crystal growth, providing an efficient way for the uptake of trace element from a related undersaturated bulk fluid.

Description: The aperiodic nature of geomagnetic field variations, both in intensity and direction, can aid in dating archaeological artefacts, volcanic rocks, and sediment records that carry a palaeomagnetic signal. The success of palaeomagnetic dating relies upon our knowledge of past field variations at specific locations. Regional archaeo- and palaeomagnetic reference curves and predictions from global geomagnetic field models provide our best description of field variations through the Holocene. State-of-the-art palaeomagnetic laboratory practices and accurate independent age controls are prerequisites for deriving reliable reference curves and models from archaeological, volcanic, and sedimentary palaeomagnetic data. In this review paper we give an overview of these prerequisites and the available reference curves and models, discuss techniques for palaeomagnetic dating, and outline its limitations. In particular, palaeomagnetic dating on its own cannot give unique results, but rather serves to refine or confirm ages obtained by other methods. Owing to the non-uniform character of magnetic field variations in different regions, care is required when choosing a palaeomagnetic dating curve, so that the distance between the dating curve and the record to be dated is not too large. Accurate reporting and incorporation of new, independently dated archaeo- and palaeomagnetic results into databases will help to improve reference curves and global models for all regions on Earth.

Description: QuantumFrontiers_HLSST_SLR_COMB2019s is a series of monthly gravity field models based on high-low satellite-to-satellite (HLSST) tracking and satellite laser ranging (SLR) data up to degree and order 60. The combination of HLSST and SLR data is done on the normal equation level using Variance Component Estimation. The series spans from 2003 to 2018 and thus covers the entire period between GRACE and GRACE Follow-On. It is therefore a prime candidate to bridge the data gap between these two satellite mission considering long-wavelength features on a global scale. The model has been developed with data contributions from the Astronomical Institute, University Bern (AIUB), the Institute of Geodesy, Theoretical Geodesy and Satellite Geodesy, Graz University of Technology, the Institute for Geodesy, Leibniz University Hannover and the European Space Agency. More details on the processing can be found in "Time-Variable Gravity Signal in Greenland Revealed by High-Low Satellite-to-Satellite Tracking" (Weigelt et al, 2013, https://doi.org/10.1002/jgrb.50283) Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers – 390837967.

Description: Magmatic-hydrothermal systems form a variety of ore deposits at different proximities to upper-crustal hydrous magma chambers, ranging from greisenization in the roof zone of the intrusion, porphyry mineralization at intermediate depths to epithermal vein deposits near the surface. The physical transport processes and chemical precipitation mechanisms vary between deposit types and are often still debated. For this study, we investigate the fluid evolution from proximal to distal settings at the Pirquitas and Chinchillas Mines in NW Argentina and the Sweet Home Mine, Colorado. New results from fluid inclusion and isotopic analyses indicate a contribution of magmatic fluids in the formation of the SnAg Pirquitas Mine, even though no direct association to a magmatic intrusion is visible. Therefore, this deposit may represent a rather distal setting. In contrast, the Ag-Pb-Zn Chinchillas Mine is hosted in volcanic extrusive units and is directly associated to an underlying dacite diatreme. In that respect, this deposit is proximal to a volcanic complex, but due to its shallow emplacement is distal to an inferred magmatic intrusion at depth. The Ag-polymetallic Sweet Home Mine (currently mined for gemmy rhodochrosite) is related to an assumed hidden Mo porphyry, but may be located more proximal to a magmatic intrusion as compared to the other deposits. Performing fluid inclusion analysis, Raman spectroscopy, noble gas isotopic compositions and LA-ICPMS measurements as well as the analysis of stable (H, O, S) and radiogenic (Pb, Sr) isotopic compositions, we aim to reconstruct the evolution and P-T-x properties of the ore-forming fluids in the respective ore deposits. As all studied deposits are characterized by a distinct sulfide mineralization stage, we also investigate whether this stage has formed by mixing of magmatic fluids with variable amounts of externally derived fluids. Furthermore, numerical modelling of the transition from a porphyry to an epithermal environment, considering country rock permeability, fluid pressure distribution, fluid temperatures, and varying locations of the magmatic plume, is used to build a quantitative model for the formation of these types of epithermal deposits.

Description: Samples of the Cu2Cd x Zn1−x SnS4 solid solution series were synthesized by a mechanochemical process, exhibiting high crystallinity due to an annealing step under flowing H2S gas. The composition-dependent structural transition between the kesterite- and stannite-type phases was determined for Cd content close to x Cd ≈ 0.4 by means of x-ray diffraction and Raman spectroscopic probes, in excellent agreement with earlier investigations. Our DFT calculations predicted a critical Cd concentration value of x Cd = 0.5 as the 'border' between the stannite- and kesterite-type structure in the Cu2Cd x Zn1−x SnS4 solid solution series. The somewhat higher calculated Cd content value compared to the experimental case can be accounted by partial Cu/Zn disorder present in the synthesized samples. The measured optical band gaps E g of the Cu2Cd x Zn1−x SnS4 solid solution series decrease by ~0.3 eV upon immediate introduction of Cd into the lattice, with E g being almost constant with varying Cd concentration. All of our observations are interpreted within the framework of earlier reports on composition-dependent kesterite-to-stannite transition, where local structural variations due to the Zn2+ substitution by the larger Cd2+ cations appear to dictate the transition process.

Description: Nataliakulikite, Ca4Ti2(Fe3+,Fe2+)(Si,Fe3+,Al)O11, is a mineral intermediate between perovskite CaTiO3 and brownmillerite Ca2(Fe,Al)2O5. It was discovered as a minor mineral in a high-temperature pyrometamorphic larnite-gehlenite rock at the Nahal Morag Canyon of the Hatrurim Basin, Israel. Nataliakulikite is associated with larnite, flamite, gehlenite, magnesioferrite, Fe3+-rich perovskite, fluorapatite, barite, Hashemite, and retrograde phases (afwillite, hillebrandite, portlandite, calcite, ettringite, hydrogarnet, and other hydrated Ca-silicates). The mineral forms brown subhedral or prismatic grains (up to 20 µm) and their intergrowths (up to 50 μm). Its empirical formula (n = 47) is (Ca3.992Sr0.014U0.004)(Ti1.933Zr0.030Nb0.002) (Fe3+0.610Fe2+0.405Cr0.005Mn0.005)(Si0.447Fe3+0.337Al0.216)O11 and shows Si predominance in tetrahedral site. The unit-cell parameters (HRTEM data) and space group are: a = 5.254, b = 30.302, c = 5.488 Å, V = 873.7 Å3, Pnma, Z = 4. These dimensions and Electron backscatter diffraction (EBSD) data strongly support the structural identity between nataliakulikite and synthetic Ca4Ti2Fe3+2O11 (2CaTiO3∙Ca2Fe3+2O5), an intermediate compound in the system CaTiO3-Ca2Fe3+2O5. In general, this mineral is a Si-Fe2+-rich natural analog of synthetic Ca4Ti2Fe3+2O11. The X-ray powder diffraction data (CuKα -radiation), calculated from unit-cell dimensions, show the strongest lines {d [Å], (Icalc)} at: 2.681(100), 1.898(30), 2.627(26), 2.744(23), 1.894(22), 15.151(19), 1.572(14), 3.795(8). The calculated density is 4.006 g/cm3. The crystal structure of nataliakulikite has not been refined because of small sizes of grains. The Raman spectrum shows strong bands at 128, 223, 274, 562, and 790 cm−1. Nataliakulikite from the Hatrurim Basin crystallized under the conditions of combustion metamorphism at high temperatures (1160–1200 °C) and low pressures (HT-region of the spurrite-merwinite facies).

Description: The chemistry of organic compounds is based on carbon, the fifteenth most abundant element in the crust. Deriving from mainly biological systems, organic compounds can be incorporated into sedimentary rocks, and remain within the lithosphere for extended geological time periods, undergoing lengthy exposure to elevated temperatures and pressures which results in chemical transformations and physical redistributions. Ultimately these compounds are returned to the Earth’s surface and atmosphere where they are oxidized back to CO2. This is the carbon cycle. While dissolved organic matter (DOM) has been studied extensively in the early parts of that cycle, very little is known about the occurrence and composition of DOM in organic-rich sedimentary rocks such as black shales and coals. The aim of this thesis was to quantitatively and molecularly characterize DOM of black shales and coals in order to examine factors controlling its liberation and composition. Simulated water extraction experiments have been performed using four Type II marine shales namely the Posidonia, Duvernay, Bakken, and Alum shales and Type III New Zealand coals. Different chromatographic and mass spectrometric methods, namely liquid chromatography-organic carbon detection (LC-OCD), ion chromatography (IC), gas chromatography-mass spectrometry (GC-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) were employed in unravelling the composition and concentration of the extracted DOM in the water extracts. Furthermore, Rock-Eval pyrolysis, pyrolysis - gas chromatography (Py-GC) were also carried out to examine the organic matter properties of the original samples. Using LC-OCD, the DOC yields of all the samples have been found to decrease steeply with increasing diagenesis and remain low throughout catagenesis. When normalized to TOC, the concentrations of DOC are comparable for the coal and shale samples with the same maturity. Using size exclusion chromatography (SEC), the extracted DOM was divided into four different fractions: Macro-2, Macro-3, Acids and Neutrals. Relatively high amounts of Macro-2 and Macro-3 fractions can be observed in the extracted DOM of the immature samples while the extracted DOM of the mature and overmature samples are featured by high amount of Neutrals. The Macro-2 and Macro-3 fractions in the extracted DOM of coals tend to contain more aromatic compounds and the molecular masses of most constituents within these two fractions are higher than for the shale extracts. With the analysis of IC, formate and acetate have been identified as the two main low molecular weight organic acids (LMWOAs) in the extracted DOM. The concentrations of formate and acetate decrease with increasing maturation of most shale samples and remain low after reaching the oil window except for the three overmature Posidonia shales from the Haddessen well. High acetate concentrations observed in the overmature samples are speculated to be caused by the hydrothermal brines. The brines might provide water and heat source to enhance the generation of acetate. To get further insights into the molecular composition of the extracted DOM, FT-ICR-MS has been applied to the solid-phase extractable DOM of New Zealand coals and Posidonia shales. In the extracted DOM of the coals, Ox class is the prominent elemental class with more than 80% TMIA. The distributions of the Ox class and the DBE of each oxygen class are quite similar for the extracted DOM of the two lignites, and show big differences to those of the three bituminous coals. The variations of average DBE of the oxygen classes have been calculated to infer the oxygen-containing functional groups. More hydroxyl and ether groups are involved in the O1-5 classes and more carboxyl and carbonyl functional groups are involved in O9-16 classes. The low abundance of O9-16 in the extracts of the bituminous coals compared to the extracts of lignites is likely due to the loss of oxygen via eliminations of carboxyl and carbonyl groups during the zone of organic diagenesis (〈 0.5% Ro). The oxygen-containing compounds in the extracted DOM of the bituminous coal are more aromatic than that of the lignites as evaluated by a newly developed aromaticity index (AIcoal). Different from the coal extracts, the extracted DOM of the Posidonia shales is dominated by the SzOx elemental class followed by the Ox class. The relative intensities of S1Ox classes show a Gaussian distribution with the highest intensity in S1O5 or S1O6 class, while the distribution of relative intensities of Ox classes varies for the shale samples with different maturity. Based on the DBE distributions and the carbon number distributions of Ox and S1Ox classes, the molecular core structure of most compounds in the mature shale extracts are speculated to contain an additional benzene ring compared to the immature shale extracts. Sulfonic acid function has been deduced to be the common functional group in S1O≥3 classes. The general composition of DOM in the water extracts is compared with that of the solvent extracts of the same samples, and the enormous differences indicate that the extracted DOM composition is strongly determined by the polarity of the organic compounds.

Description: Die Chemie organischer Verbindungen ist geprägt durch das Element Kohlenstoff, das in der Häufigkeitsverteilung der Elemente in der Erdkruste an 15. Stelle steht. Aus biologischen Systemen stammend werden organische Verbindungen in Sedimentgesteine eingebaut und verbleiben über geologische Zeiträume in der Lithosphäre und durchlaufen dabei chemische Prozesse und physikalische Umverteilungen in Abhängigkeit von erhöhten Temperaturen und Drücken. Letztendlich gelangen organische Verbindungen wieder an die Erdoberfläche und in die Atmosphäre, wo sie zu CO2 oxidiert werden. Dies ist der Kohlenstoffkreislauf. Während gelöstes organisches Material (dissolved organic matter – DOM) in den frühen Phasen dieses Kreislaufes bereits intensiv untersucht wurden, ist wenig bekannt über das Vorkommen und die Zusammensetzung des DOM in Sedimentgesteinen mit hohem Anteil an organischen Verbindungen wie Schwarzschiefer und Kohlen. Das Ziel der vorliegenden Arbeit war es das DOM aus Schiefer und Kohlen quantitativ und in seiner molekularen Zusammensetzung zu charakterisieren um die wichtigsten Einflussfaktoren für die Freisetzung und Zusammensetzung bestimmen zu können. Im Labor wurden Extraktionsexperimente durchgeführt mit Proben von vier verschiedenen Schiefergesteinen mariner Herkunft (Kerogentyp II – Posidonienschiefer, Duvernay, Bakken und Alum) und Kohleproben aus Neuseeland (Kerogentyp III). Mit verschiedenen chromatographischen und massenspektrometrischen Methoden – namentlich Flüssigkeitschromatographie-Kohlenstoffdetektion (LC-OCD), Ionenchromatographie (IC), Gaschromatographie-Massenspektrometrie (GC-MS) und Fouriertransformation-Ionenzyklotronresonanz-Massenspektrometrie (FT-ICR-MS) – wurden die Zusammensetzung und die Konzentrationen organischer Verbindungen in den wässrigen Extrakten aufgeklärt. Zusätzlich wurden die Eigenschaften des natürlichen organischen Materials in den Sedimentgesteinen mittels Rock-Eval-Pyrolyse und Pyrolyse-Gaschromatographie (Py-GC) untersucht. Mittels LC-OCD konnte festgestellt werden, dass die Gehalte an gelöstem organischem Kohlenstoff (DOC) in den Wasserextrakten mit der Diagenese des Sedimentgesteins stark zurückgehen und während der Katagenese auf geringem Niveau bleiben. Wenn die DOC-Konzentrationen auf den Gehalt an organischem Kohlenstoff im Sedimentgestein normiert wurden, ergaben sich übereinstimmende Werte für Schiefergestein und Kohlen in Abhängigkeit von der thermischen Reife des organischen Materials. Mit der Molekülgrößenausschlusschromatographie (size exclusion chromatography – SEC) konnte das extrahierte DOM in vier verschiedene Fraktionen unterteilt werden: Makro-2, Makro-3, Säuren und Neutralstoffe. In dem extrahierten DOM der unreifen Sedimentgesteine konnten relativ hohe Gehalte der Fraktionen Makro-2 und Makro-3 nachgewiesen werden, wohingegen das extrahierbare DOM aus reifen bzw. sehr reifen Proben durch hohe Anteile an Neutralstoffen charakterisiert war. In den Wasserextrakten der Kohleproben gab es in den Makro-2 und Makro-3 Fraktionen mehr aromatische Verbindungen und höhere Molekülmassen als in den Wasserextrakten der Schiefergesteine. Mit der IC wurden Formiat und Acetat als die Hauptvertreter der niedermolekularen organischen Säuren im extrahierten DOM nachgewiesen. Für die meisten Schiefergesteine zeigte sich ein Rückgang der Konzentrationen von Formiat und Acetat im extrahierten DOM in Abhängigkeit von der zunehmenden Reife des organischen Materials und sehr geringe Konzentrationen innerhalb des Ölfensters. Nur die Proben des Posidonienschiefers aus der Haddessen-Bohrung zeigten einen Anstieg der Acetat-Konzentrationen im extrahierten DOM der überreifen Gesteine, welcher mit dem Einfluss hydrothermaler Wässer im Zusammenhang stehen kann. Die hydrothermalen Wässer können als Wasser- und Energiequelle zur Bildung von Acetat beigetragen haben. Um einen tieferen Einblick in die molekulare Zusammensetzung des extrahierten DOM zu erhalten wurden die Extrakte des Posidonienschiefers und der Kohlen mit FT-ICR-MS untersucht. Der extrahierte DOM der Kohlen wird zu mehr als 80% dominiert von sauerstoffhaltigen organischen Verbindungen (Ox-Verbindungen). Die Verteilung der Ox-Verbindungen und der Doppelbindungsäquivalente (DBÄ) für jede Ox-Klasse ist ähnlich für das extrahierte DOM aus den beiden Braunkohlen jedoch deutlich verschieden für das extrahierte DOM der bituminösen Kohlen. Das berechnete durchschnittliche DBÄ (DBEaverage) der Ox-Verbindungen wurde genutzt um Annahmen über die möglichen sauerstoffhaltigen funktionellen Gruppen abzuleiten. Bei den O1-5 Verbindungen liegen vermutlich mehr Hydroxyl- und Etherfunktionalitäten vor, wohingegen die O9-16 Verbindungen eher durch Carboxyl- und Carbonylfunktionalitäten geprägt sein werden. Die geringe Häufigkeit von O9-16 Verbindungen in den wässrigen Extrakten der bituminösen Kohlen kann die Abspaltung von Carboxyl- und Carbonylfunktionalitäten während der Diagenese (〈0,5% Ro) verdeutlichen. Mit Hilfe des neu modifizierten Aromatizitätsindexes (AIcoal) konnte gezeigt werden dass die Ox-Verbindungen im extrahierten DOM der bituminösen Kohlen stärker aromatisch sind als die Ox-Verbindungen im extrahierten DOM der Braunkohlen. Im Gegensatz zu den Kohleextrakten ist das extrahierte DOM der Posidonienschiefer dominiert durch SzOx-Verbindungen, gefolgt von den Ox-Verbindungen. Die relativen Intensitäten der S1Ox-Verbindungen zeigte eine Gaußsche Verteilung mit dem Maximum bei den S1O5 bzw. den S1O6 Verbindungen, wohingegen die relativen Intensitäten der Ox-Verbindungen in ihrer Verteilung deutlich reifeabhängig sind. Anhand der Verteilungen der DBÄ und der Kohlenstoffanzahl wurden für die Ox-Verbindungen und die S1Ox-Verbindungen Rückschlüsse auf mögliche Strukturen bzw. Bestandteile der Strukturen gezogen. Das extrahierte DOM der reifen Posidonienschiefer scheint sich durch einen zusätzlichen Benzolring vom extrahierten DOM der unreifen Posidonienschiefer zu unterscheiden. Bei den S1O〉3-Verbindungen scheint die Sulfonsäure eine vorherrschende Struktur darzustellen. Die molekulare Zusammensetzung des extrahierten DOM unterscheidet sich vor allem durch die Polarität der organischen Verbindungen von der Zusammensetzung der Lösungsmittel-Extrakte der gleichen Posidonienschiefer.

Description: Skarn deposits are found on every continents and were formed at different times from Precambrian to Tertiary. Typically, the formation of a skarn is induced by a granitic intrusion in carbonates-rich sedimentary rocks. During contact metamorphism, fluids derived from the granite interact with the sedimentary host rocks, which results in the formation of calc-silicate minerals at the expense of carbonates. Those newly formed minerals generally develop in a metamorphic zoned aureole with garnet in the proximal and pyroxene in the distal zone. Ore elements contained in magmatic fluids are precipitated due to the change in fluid composition. The temperature decrease of the entire system, due to the cooling of magmatic fluids and the entering of meteoric water, allows retrogression of some prograde minerals. The Hämmerlein skarn deposit has a multi-stage history with a skarn formation during regional metamorphism and a retrogression of primary skarn minerals during the granitic intrusion. Tin was mobilized during both events. The 340 Ma old tin-bearing skarn minerals show that tin was present in sediments before the granite intrusion, and that the first Sn enrichment occurred during the skarn formation by regional metamorphism fluids. In a second step at ca. 320 Ma, tin-bearing fluids were produced with the intrusion of the Eibenstock granite. Tin, which has been added by the granite and remobilized from skarn calc-silicates, precipitated as cassiterite. Compared to clay or marl, the skarn is enriched in Sn, W, In, Zn, and Cu. These metals have been supplied during both regional metamorphism and granite emplacement. In addition, the several isotopic and chemical data of skarn samples show that the granite selectively added elements such as Sn, and that there was no visible granitic contribution to the sedimentary signature of the skarn The example of Hämmerlein shows that it is possible to form a tin-rich skarn without associated granite when tin has already been transported from tin-bearing sediments during regional metamorphism by aqueous metamorphic fluids. These skarns are economically not interesting if tin is only contained in the skarn minerals. Later alteration of the skarn (the heat and fluid source is not necessarily a granite), however, can lead to the formation of secondary cassiterite (SnO2), with which the skarn can become economically highly interesting.

Description: Skarn-Lagerstätten befinden sich auf allen Kontinenten und wurden zu unterschiedlichen Zeiten vom Präkambrium bis zum Tertiär gebildet. Typischerweise wird die Bildung eines Skarns durch die Intrusion eines Granits in karbonatreiche Sedimentgesteine induziert. Während der Kontaktmetamorphose reagieren die Fluide aus dem Granit mit dem sedimentären Wirtgestein, was zur Bildung von Kalksilikaten auf Kosten von Karbonaten führt. Diese neu gebildeten Minerale entwickeln sich im Allgemeinen in einer metamorph zonierten Aureole mit Granat im proximalen und Pyroxen im distalen Bereich. Erzelemente die in magmatischen Fluiden enthalten sind werden aufgrund der veränderten Fluidzusammensetzung ausgefällt. Die Temperaturabsenkung des gesamten Systems, hervorgerufen durch die Abkühlung von magmatischen Fluiden sowie durch das Eindringen meteorischen Wassers, führen zu teilweisen oder vollständigen Umwandlung prograder Minerale. Die Skarn-Lagerstätte Hämmerlein hat eine mehrstufige Geschichte mit Skarnsbildung während der regionalen Metamorphose und Retrogression der primären Skarn-Minerale während der Intrusion von Graniten. Zinn wurde während beiden Ereignissen mobilisiert. Die 340 Ma alten zinnhaltigen Skarnminerale zeigen, dass Zinn in Sedimenten bereits vor dem Graniteintrag vorhanden war, und dass die erste Sn-Anreicherung während der Bildung des Skarns durch Fluide der Regionalmetamorphose stattfand. In einem zweiten Schritt um 320 Ma wurden Zinn-haltige Fluide durch die Intrusion des Eibenstockgranits freigesetzt. Diese Fluide überprägten den Skarn. Das freisetzen und das neu zugefügte Zinn ist in Kassiterit gebunden und führten dem System zusätzliches Zinn zu, wobei Zinn aus den Skarn-Kalksilikaten remobilisiert wurde. Im Vergleich zu Tonstein oder Mergel sind die Skarn mit Sn, W, In, Zn, und Cu angereichet. Diese Metalle sind während der Regionalmetamorphose und der Granitplatznahme zu unterschiedlichen Teilen zugeführt worden. Darüber hinaus zeigen die verschiedenen isotopen und chemischen Daten der Skarn-Proben, dass der Granit selektiv einige Elemente wie Sn hinzugefügt, und dass es keinen sichtbar granitischen Beitrag zur sedimentären Signatur des Skarns gab. Das Beispiel Hämmerlein zeigt, dass es möglich ist einen zinnreichen Skarn ohne zugehörigen Granit zu bilden, wenn Zinn von zinnhaltigen Sedimenten während einer Regionalmetamorphose mit wässrigen metamorphen Fluiden transportiert worden ist. Diese Skarne sind wirtschaftlich uninterssant wenn das Zinn nur in den Skarn-Mineralen enthalten ist. Spätere Umwandlung des Skarns (die Quelle der Wärme und Fluiden ist nicht unbedingt ein Granit) kann jedoch zur Bildung von sekundärem Kassiterite (SnO2) führen, womit der Skarn plötzlich wirtschaftlich hoch interessant sein kann.

Description: A detailed and precise knowledge of ocean bottom topography is essential in many geoscientific and oceanographic applications. Shipborne echo sounding provides the only direct bathymetric method. However, even after decades of applying this technique only a fraction of the global ocean could be covered. Alternatively, gravity data inversion is a feasible method to infer ocean bottom topography since the gravity field correlates with topography at short to medium wavelengths. Gravity field observables are globally provided by dedicated satellite missions like GOCE, GRACE and GRACE-FO and, over the oceans, by satellite altimetry. Regional and local measurements are realised by means of ground-based, shipborne and airborne gravimetry. For the first time in Europe a jet aircraft was used for airborne gravimetry. During the GEOHALO flight campaign over Italy and the Tyrrhenian, Ionian and Adriatic seas in June 2012, the German research aircraft HALO carried an entire suite of geodetic-geophysical instrumentation, including gravity metres. The careful processing of the gravity data acquired by the CHEKAN-AM instrument of the German Research Centre for Geosciences allowed to achieve an accuracy at the mGal level. Subsequently, the Parker–Oldenburg inversion was applied to predict ocean bottom topography along the GEOHALO profiles flown over the ocean. To constrain the parameter space in the inversion we used the Crust1.0 model. Finally, the obtained results were compared to the General Bathymetric Chart of the Oceans in order to estimate the performance of the method. Our study demonstrates that airborne gravimetry aboard a jet aircraft is capable to provide valuable data for regional geoscientific studies.

Description: The advances in modern geodetic techniques such as the global navigation satellite system (GNSS) and synthetic aperture radar (SAR) provide surface deformation measurements with an unprecedented accuracy and temporal and spatial resolutions even at most remote volcanoes on Earth. Modelling of the high-quality geodetic data is crucial for understanding the underlying physics of volcano deformation processes. Among various approaches, mathematical models are the most effective for establishing a quantitative link between the surface displacements and the shape and strength of deformation sources. Advancing the geodetic data analyses and hence, the knowledge on the Earth’s interior processes, demands sophisticated and efficient deformation modelling approaches. Yet the majority of these models rely on simplistic assumptions for deformation source geometries and ignore complexities such as the Earth’s surface topography and interactions between multiple sources. This thesis addresses this problem in the context of analytical and numerical volcano deformation modelling. In the first part, new analytical solutions for triangular dislocations (TDs) in uniform infinite and semi-infinite elastic media have been developed. Through a comprehensive investigation, the locations and causes of artefact singularities and numerical instabilities associated with TDs have been determined and these long-standing drawbacks have been addressed thoroughly. This approach has then been extended to rectangular dislocations (RDs) with full rotational degrees of freedom. Using this solution in a configuration of three orthogonal RDs a compound dislocation model (CDM) has been developed. The CDM can represent generalized volumetric and planar deformation sources efficiently. Thus, the CDM is relevant for rapid inversions in early warning systems and can also be used for detailed deformation analyses. In order to account for complex source geometries and realistic topography in the deformation models, in this thesis the boundary element method (BEM) has been applied to the new solutions for TDs. In this scheme, complex surfaces are simulated as a continuous mesh of TDs that may possess any displacement or stress boundary conditions in the BEM calculations. In the second part of this thesis, the developed modelling techniques have been applied to five different real-world deformation scenarios. As the first and second case studies the deformation sources associated with the 2015 Calbuco eruption and 2013–2016 Copahue inflation period have been constrained by using the CDM. The highly anisotropic source geometries in these two cases highlight the importance of using generalized deformation models such as the CDM, for geodetic data inversions. The other three case studies in this thesis involve high-resolution dislocation models and BEM calculations. As the third case, the 2013 pre-explosive inflation of Volcán de Colima has been simulated by using two ellipsoidal cavities, which locate zones of pressurization in the volcano’s lava dome. The fourth case study, which serves as an example for volcanotectonics interactions, the 3-D kinematics of an active ring-fault at Tendürek volcano has been investigated through modelling displacement time series over the 2003–2010 time period. As the fifth example, the deformation sources associated with North Korea’s underground nuclear test in September 2017 have been constrained. These examples demonstrate the advancement and increasing level of complexity and the general applicability of the developed dislocation modelling techniques. This thesis establishes a unified framework for rapid and high-resolution dislocation modelling, which in addition to volcano deformations can also be applied to tectonic and humanmade deformations.

Description: Fortschritte in modernen geodätischen Techniken wie dem globalen Navigationssatellitensystem (GNSS) und dem Synthetic Apertur Radar (SAR), liefern Messungen der Oberflächenverformung mit einer beispiellosen Genauigkeit sowie zeitlichen und räumlichen Auflösungen, selbst an abgelegensten Vulkanen. Die Modellierung von hochqualitativen geodätischen Daten ist entscheidend für das Verständnis der zugrundeliegenden Physik der Verformungsprozesse an diesen Vulkanen. Um eine quantitative Verbindung zwischen den Oberflächenverschiebungen und der Form und Stärke von Verformungsquellen herzustellen, sind mathematische Modelle am effektivsten. Die Fortschnitte in geodätischen Datenanalysen und damit das Wissen über die Prozesse im Inneren der Erde erfordern ausgefeilte und effiziente Ansätze der Verformungsmodellierung. Die meisten dieser Modelle beruhen jedoch auf vereinfachten Annahmen der Geometrien der Verformungsquellen und ignorieren Komplexitäten wie die Erdoberflächentopographie und Wechselwirkungen zwischen mehreren Quellen. Diese Doktorarbeit befasst sich mit diesem Problem im Kontext der analytischen und numerischen Vulkanverformungsmodellierung. Im ersten Schritt wurden neue analytische Lösungen für dreieckige Dislokationen (triangular dislocation-TD) im gleichförmigen elastischen Voll- und Halbraum entwickelt. Durch eine umfassende Untersuchung wurden die Orte und Ursachen von TDs verbundenen Artefaktsingularitäten und numerischen Instabilitäten identifiziert und diese Problematik gelöst. Dieser Ansatz wurde dann auf rechteckige Dislokationen (rectangular dislocation-RD) mit vollen Rotationsfreiheitsgraden erweitert. Unter Verwendung dieser Lösung in einer Konfiguration von drei orthogonalen RDs wurde ein “Zusammengesetztes Dislokationsmodel” (compound dislocation model-CDM) entwickelt. Das CDM kann verallgemeinerte volumetrische und planare Verformungsquellen effizient darstellen. Somit ist das CDM für schnelle Inversionen in Frühwarnungssystemen relevant und kann auch für detaillierte Verformungsanalysen verwendet werden. Um komplexe Quellengeometrien und eine realistische Topographie in den Verformungsmodellen dieser Untersuchung zu berücksichtigen, wurde die Randelementmethode (REM) auf die neuen Lösungen für TDs angewendet. In diesem Schema werden komplexe Oberflächen als ein kontinuierliches Netz von DVs simuliert, die in den REM-Berechnungen beliebige Verschiebungs- oder Spannungsgrenzbedingungen aufweisen können. Als Beispiele wurden die entwickelten Modellierungstechniken auf fünf verschiedene reale Verformungsszenarien angewendet. Das erste und zweite Beispiel, die Calbuco-Eruption 2015 und die 2013–2016 Copahue-Aufwölbungsperiode, wurden durch die Verwendung des CDM näher beschrieben. Die hoch anisotropen Quellengeometrien in diesen beiden Fällen unterstreichen die Bedeutung der Verwendung verallgemeinerter Verformungsmodelle wie dem CDM für geodätische Dateninversionen. Weitere Fallstudien dieser Doktorarbeit umfassen hochauflösende Versetzungsmodelle und REM-Berechnungen. Die Aufwölbung 2013 am Volcán de Colima wurde simuliert, indem zwei ellipsoidale Quellen verwendet wurden, die Druckzonen im Lavadom des Vulkans lokalisieren. Danach, als Beispiel für Vulkantektonik-Interaktionen, wurde die 3-D-Kinematik einer aktiven Ringstörung am Tendürek-Vulkan durch Modellierung von InSAR-Zeitreihen über die Zeitperiode 2003–2010 simuliert. Als letztes Beispiel wurden die Verformungsquellen, die im Zusammenhang mit Nordkoreas unterirdischem Atomtest im September 2017 stehen, simuliert und der Einsatz der verwendeten Methoden auch in nicht vulkanischen Terrain gezeigt. Diese Beispiele zeigen den Fortschritt und das zunehmende Niveau der Komplexität und die allgemeine Anwendbarkeit der entwickelten Dislokationsmodellierungstechniken. Diese Doktorarbeit unterstreicht die Anwendung von neuer schneller und hochauflösender Dislokationsmodellierung, die neben Vulkanverformungen auch auf tektonische und vom Menschen verursachte Verformungen angewendet werden kann.

Description: Earthquake swarms are characterized by large numbers of events occurring in a short period of time within a confined source volume and without significant mainshock aftershock pattern as opposed to tectonic sequences. Intraplate swarms in the absence of active volcanism usually occur in continental rifts as for example in the Eger Rift zone in North West Bohemia, Czech Republic. A common hypothesis links event triggering to pressurized fluids. However, the exact causal chain is often poorly understood since the underlying geotectonic processes are slow compared to tectonic sequences. The high event rate during active periods challenges standard seismological routines as these are often designed for single events and therefore costly in terms of human resources when working with phase picks or computationally costly when exploiting full waveforms. This methodological thesis develops new approaches to analyze earthquake swarm seismicity as well as the underlying seismogenic volume. It focuses on the region of North West (NW) Bohemia, a well studied, well monitored earthquake swarm region. In this work I develop and test an innovative approach to detect and locate earthquakes using deep convolutional neural networks. This technology offers great potential as it allows to efficiently process large amounts of data which becomes increasingly important given that seismological data storage grows at increasing pace. The proposed deep neural network trained on NW Bohemian earthquake swarm records is able to locate 1000 events in less than 1 second using full waveforms while approaching precision of double difference relocated catalogs. A further technological novelty is that the trained filters of the deep neural network’s first layer can be repurposed to function as a pattern matching event detector without additional training on noise datasets. For further methodological development and benchmarking, I present a new toolbox to generate realistic earthquake cluster catalogs as well as synthetic full waveforms of those clusters in an automated fashion. The input is parameterized using constraints on source volume geometry, nucleation and frequency-magnitude relations. It harnesses recorded noise to produce highly realistic synthetic data for benchmarking and development. This tool is used to study and assess detection performance in terms of magnitude of completeness Mc of a full waveform detector applied to synthetic data of a hydrofracturing experiment at the Wysin site, Poland. Finally, I present and demonstrate a novel approach to overcome the masking effects of wave propagation between earthquake and stations and to determine source volume attenuation directly in the source volume where clustered earthquakes occur. The new event couple spectral ratio approach exploits high frequency spectral slopes of two events sharing the greater part of their rays. Synthetic tests based on the toolbox mentioned before show that this method is able to infer seismic wave attenuation within the source volume at high spatial resolution. Furthermore, it is independent from the distance towards a station as well as the complexity of the attenuation and velocity structure outside of the source volume of swarms. The application to recordings of the NW Bohemian earthquake swarm shows increased P phase attenuation within the source volume (Qp 〈 100) based on results at a station located close to the village Luby (LBC). The recordings of a station located in epicentral proximity, close to Nový Kostel (NKC), show a relatively high complexity indicating that waves arriving at that station experience more scattering than signals recorded at other stations. The high level of complexity destabilizes the inversion. Therefore, the Q estimate at NKC is not reliable and an independent proof of the high attenuation finding given the geometrical and frequency constraints is still to be done. However, a high attenuation in the source volume of NW Bohemian swarms has been postulated before in relation to an expected, highly damaged zone bearing CO 2 at high pressure. The methods developed in the course of this thesis yield the potential to improve our understanding regarding the role of fluids and gases in intraplate event clustering.

Description: Erdbebenschwärme zeichnen sich durch eine große Anzahl an Ereignissen in einem relativ kleinen Zeitraum und Volumen aus. Im Gegensatz zu tektonischen Sequenzen ist in der Regel keine signifikantes Muster von Vor- und Nachbeben erkennbar. In Abwesenheit aktiven Vulkanismusses, kommen Erdbebenschwärme innerhalb kontinentaler Platten häufg an kontinentalen Verwerfungen vor, wie Beispielsweise im Bereich des Egergrabens im nordböhmischen Becken (Tschechien). Eine übliche Hypothese verbindet den Erdbebenentstehungsprozess mit Hochdruckfluiden. Der exakte kausale Zusammenhang ist jedoch häufig enigmatisch, da die zugrundeliegenden geotektonischen Prozesse im Vergleich zu tektonischen Sequenzen relativ langsam sind. Die hohe Erdbebenrate während aktiver Phasen stellt hohe Anforderungen an etablierte seismologische Routinen da diese häufg für Einzelereignisse konzipiert sind. So können sie einen hohen Aufwand bei manueller Selektion seismischer Phasen (picking) bedeuten oder rechenerisch aufwändig sein wenn volle Wellenformen verarbeitet werden sollen. Im Rahmen dieser methodologischen Thesis werden neue Ansätze zur Analyse seismischer Schwärme, sowie des zugrundeliegenden seismogenen Volumens entwickelt. Der Fokus liegt hierbei auf der gut untersuchten und überwachten nordböhmischen Schwarmregion. Ich entwickle und teste in dieser Arbeit einen innovativen Ansatz zur Detektion und Lokalisation von Erdbeben basierend auf einem tiefen konvolvierenden neuronalen Netzwerk. Diese Technologie bietet großes Potential da sie es erlaubt große Datenmengen effizient zu verarbeiten was durch die zunehmenden Datenmengen seismologischer Datenzentren immer weiter an Bedeutung gewinnt. Das entwickelte tiefe neuronale Netzwerk, trainiert auf Aufnahmen nordböhmischer Erdbebenschwärme, ist in der Lage 1000 Eregnisse in weniger als 1 Sekunde bei Verwendung voller Wellenformen zu lokalisieren und erreicht eine Präzision die vergleichbar ist mit der Genauigkeit eines Katalogs, der mittels Doppelte Differenzen Methode relokalisiert wurde. Eine weitere technologische Neuheit ist, dass die trainierten Filter der ersten Schicht des tiefen neuronalen Netzwerkes als Mustererkennungsfilter umfunktioniert werden und damit als Ereignisdetektor dienen können, ohne, dass zuvor explizit auf Rauschdaten trainiert werden muss. Für die weitere technologische Entwicklung stelle ich ein neues, automatisiertes Werkzeug für die synthetisierung realistischer Erdbebenschwarmkataloge, sowie hierauf basierender synthetischer voller Wollenform vor. Die Eingabeparameter werden durch die Geometrie des Quellvolumens, der Nukleationscharakteristik und Magnitude-Häufigkeitsverteilung definiert. Weiter können Rauschsignale realer Daten verwendet werden um äußerst realistische synthetische Daten zu generieren. Dieses Werkzeug wird verwendet um die Vollständigkeitmagnitude eines Detektors für volle Wellenformen anhand synthetischer Daten zu evaluieren. Die synthetisierten Daten sind Motiviert durch ein Hydrofrackingexperiment in Wysin (Polen). Des Weiteren stelle ich einen neuen Ansatz vor, der die Effekte der Wellenausbreitung zwischen Erdbeben und Stationen ausblendet und die Bestimmung der Dämpfung unmittelbar im Quellvolumen von Schwarmerdbeben erlaubt. Diese neue Methode benutzt das hochfrequente spektrale Verhältnis von Ereignispaaren mit gemeinsamen Strahlenwegen. Synthetische Tests zeigen, dass die Methode in der Lage ist die Dämpfung innerhalb des Quellvolumens mit hoher räumlicher Genauigkeit zu bestimmen. Weiter ist sie im Einzelnen unabhängig von der Entfernung zwischen Ereignis und Station als auch von der Komplexität der Dämpfungs und Geschwindigkeitsstruktur außerhalb des Quellvolumens. Die Anwendung auf Daten des nordböhmischen Erdbebenschwarms zeigt eine erhöhte P Phasen Dämpfung im Quellvolumen (Qp 〈 100) basierend auf Daten einer Station in der Nähe des Dorfes Luby (LBC). Die Wellenformen einer Station in unmittelbarer epizentraler Nähe, bei Novy Kostel (NKC), weisen eine relativ hohe Komplexität auf, was darauf hindeutet, dass seismische Wellen, die diese Station erreichen relativ stark gestreut werden im Vergleich zu anderen Stationen. Das hohe Maß an Komplexität destabilisiert die Methode und führt zu ungenauen Schätzungen an der Station NKC. Daher bedarf es einer weiteren unabhängigen Validierung der hohen Dämpfung bei gegebenen geometrischen und spektralen Voraussetzungen. Nichtsdestoweniger wurde bereits eine hohe Dämpfung im Quellvolumen der nordböhmischen Schwärme postuliert und erwartet, insbesondere im Zusammenhang mit einer Zone hoher Brüchigkeit die CO2 bei hohen Drücken beinhaltet. Die Methoden die im Rahmen dieser Thesis entwickelt werden haben das Potential unser Verständnis bezüglich der Rolle von Fluiden und Gasen bei Erdbebenschärmen innerhalb kontinentaler Platten zu verbessern.

Description: Photosynthesis is one of the most fundamental processes on Earth fuelling life by providing food and energy. Moreover, terrestrial vegetation is a key element in the climate system as it importantly affects exchange processes of carbon, water and energy between the land surface and the atmosphere. In times of a changing climate there is urgent need for detailed knowledge on the factors driving plant activity and for reliable observational systems of the terrestrial vegetation. Satellite remote sensing is the only means to obtain measurements with global coverage, including remote and inaccessible regions, in a spatially and temporally continuous manner. This thesis presents an assess- ment of our current observational capabilities of vegetation dynamics from space. Three complementary approaches of spaceborne ecosystem monitoring are inter-compared: 1) Spectral measurements of the land surface reflectance in the optical range give an indica- tion of the amount of green biomass (as an integrative signal of leaf quantity and quality) and hence of the potential to perform photosynthesis. 2) In the red and far-red spectral regions, satellite instruments register a very small additive signal to the reflected radiance which originates from photosynthetically active chlorophyll pigments, termed sun-induced chlorophyll fluorescence (SIF). 3) Carbon fluxes measured in-situ are upscaled to a global data set of model gross photosynthetic carbon uptake (known as GPP - gross primary production) using empirical relationships with remotely sensed land surface and environ- mental variables. Three case studies focus i) on the spring phenology in boreal forests, ii) on the peak growing season in circumpolar treeless regions, and iii) on phenological changes in ecosystems with varying abundances of trees globally in times of fluctuations in soil moisture availability. The results of all three case studies highlight the intrinsic differences between greenness on the one hand and photosynthetic activity on the other hand. Specifically – for the first time on synoptic scales – a decoupling of photosynthesis (as indicated by SIF and model GPP) and greenness (approximated by various indices derived from spectral reflectance measurements) could be observed in evergreen needleleaf forests during spring recovery. Similarly, a temporal mismatch occurs in northern hemi- sphere forests during the growing season. There, changes in incoming light co-vary with soil moisture and immediately affect photosynthetic performance but barely greenness. Moreover, it has emerged that the timing of peak photosynthesis and peak greenness are asynchronous in tundra areas, which is indicative of differing dynamics. Conversely, there is high consistency between the three approaches regarding the length of growing season in deciduous forests and moisture-related phenological shifts in non-forested ecosystems. The work in this thesis demonstrates that SIF represents an asset for the monitoring of the dynamics of photosynthesis and carbon uptake compared to greenness-based ap- proaches. There are further indications of SIF to track changes in photosynthetic yields. However, despite these promising results for the accurate tracking of photosynthesis from space, further research is required to provide higher resolution data sets with clearer sig- nals. Further, ground-based validation efforts are necessary to improve our mechanistic understanding of physiological and radiative transfer processes controlling the SIF signal.

Description: Partial melting is a first order process for the chemical differentiation of the crust (Vielzeuf et al., 1990). Redistribution of chemical elements during melt generation crucially influences the composition of the lower and upper crust and provides a mechanism to concentrate and transport chemical elements that may also be of economic interest. Understanding of the diverse processes and their controlling factors is therefore not only of scientific interest but also of high economic importance to cover the demand for rare metals. The redistribution of major and trace elements during partial melting represents a central step for the understanding how granite-bound mineralization develops (Hedenquist and Lowenstern, 1994). The partial melt generation and mobilization of ore elements (e.g. Sn, W, Nb, Ta) into the melt depends on the composition of the sedimentary source and melting conditions. Distinct source rocks have different compositions reflecting their deposition and alteration histories. This specific chemical “memory” results in different mineral assemblages and melting reactions for different protolith compositions during prograde metamorphism (Brown and Fyfe, 1970; Thompson, 1982; Vielzeuf and Holloway, 1988). These factors do not only exert an important influence on the distribution of chemical elements during melt generation, they also influence the volume of melt that is produced, extraction of the melt from its source, and its ascent through the crust (Le Breton and Thompson, 1988). On a larger scale, protolith distribution and chemical alteration (weathering), prograde metamorphism with partial melting, melt extraction, and granite emplacement are ultimately depending on a (plate-)tectonic control (Romer and Kroner, 2016). Comprehension of the individual stages and their interaction is crucial in understanding how granite-related mineralization forms, thereby allowing estimation of the mineralization potential of certain areas. Partial melting also influences the isotope systematics of melt and restite. Radiogenic and stable isotopes of magmatic rocks are commonly used to trace back the source of intrusions or to quantify mixing of magmas from different sources with distinct isotopic signatures (DePaolo and Wasserburg, 1979; Lesher, 1990; Chappell, 1996). These applications are based on the fundamental requirement that the isotopic signature in the melt reflects that of the bulk source from which it is derived. Different minerals in a protolith may have isotopic compositions of radiogenic isotopes that deviate from their whole rock signature (Ayres and Harris, 1997; Knesel and Davidson, 2002). In particular, old minerals with a distinct parent-to-daughter (P/D) ratio are expected to have a specific radiogenic isotope signature. As the partial melting reaction only involves selective phases in a protolith, the isotopic signature of the melt reflects that of the minerals involved in the melting reaction and, therefore, should be different from the bulk source signature. Similar considerations hold true for stable isotopes.

Description: Partielle Schmelzbildung ist ein zentraler Prozess für die geochemische Differentiation der Erdkruste (Vielzeuf et al., 1990). Die Umverteilung chemischer Elemente während der Schmelzbildung beeinflusst die Zusammensetzung der oberen und unteren Erdkruste entscheidend und stellt einen Mechanismus zur Konzentration und zum Transport chemischer Elemente dar. Das Verständnis der diversen Prozesse und der kontrollierenden Faktoren ist deshalb nicht nur von wissenschaftlichem Interesse sondern auch von ökonomischer Bedeutung um die Nachfrage für seltene Metalle zu decken. Die Umverteilung von Haupt- und Spurenelementen während des partiellen Aufschmelzens ist ein entscheidender Schritt für das Verständnis wie sich granitgebundene Lagerstätten bilden (Hedenquist and Lowenstern, 1994). Die Schmelzbildung und die Mobilisierung von Erz-Elementen (z. B. Sn, W, Nb, Ta) in die Schmelze hängt von der Zusammensetzung der sedimentären Ausgangsgesteine und den Schmelzbedingungen ab. Verschiedene Ausgangsgesteine haben aufgrund ihrer Ablagerungs- und Verwitterungsgeschichte unterschiedliche Zusammensetzungen. Dieses spezifische geochemische „Gedächtnis“ resultiert in unterschiedlichen Mineralparagenesen und Schmelzreaktionen in verschiedenen Ausgangsgesteinen während der prograden Metamorphose. (Brown and Fyfe, 1970; Thompson, 1982; Vielzeuf and Holloway, 1988). Diese Faktoren haben nicht nur einen wichtigen Einfluss auf die Verteilung chemischer Elemente während der Schmelzbildung, sie beeinflussen auch das Volumen an Schmelze, die Extraktion der Schmelze aus dem Ausgangsgestein und deren Aufstieg durch die Erdkruste (Le Breton and Thompson, 1988). Auf einer grösseren Skala unterliegen die Verteilung der Ausgangsgesteine und deren chemische Alteration (Verwitterung), die prograde Metamorphose mit partieller Schmelzbildung, Schmelzextraktion und die Platznahme granitischer Intrusionen einer plattentektonischen Kontrolle. Das Verständnis der einzelnen Schritte und deren Wechselwirkungen ist entscheidend um zu verstehen wie granitgebunden Lagerstätten entstehen und erlaubt es, das Mineralisierungspotential bestimmter Gebiete abzuschätzen. Partielles Aufschmelzen beeinflusst auch die Isotopensystematik der Schmelze und des Restites. Die Zusammensetzungen radiogener und stabiler Isotopen von magmatischen Gesteinen werden im Allgemeinen dazu verwendet um deren Ursprungsgesteine zu identifizieren oder um Mischungsprozesses von Magmen unterschiedlichen Ursprunges zu quantifizieren (DePaolo and Wasserburg, 1979; Lesher, 1990; Chappell, 1996). Diese Anwendungen basieren auf der fundamentalen Annahme, dass die Isotopenzusammensetzung der Schmelze derjenigen des Ausgangsgesteines entspricht. Unterschiedliche Minerale in einem Gestein können unterschiedliche, vom Gesamtgestein abweichende, Isotopenzusammensetzungen haben (Ayres and Harris, 1997; Knesel and Davidson, 2002). Insbesondere für alte Minerale, mit einem unterschiedlichen Mutter-Tochter Nuklidverhältnis, ist eine spezifische Isotopenzusammensetzung zu erwarten. Da im partiellen Schmelzprozess nur bestimmte Minerale eines Gesteines involviert sind, entspricht die Isotopenzusammensetzung der Schmelze derjenigen der Minerale welche an der Schmelzreaktion teilnehmen. Daher sollte die Isotopenzusammensetzung der Schmelze von derjenigen des Ursprungsgesteines abweichen. Ähnliche Überlegungen treffen auch für stabile Isotopen zu.

Description: The Central Andes host large reserves of base and precious metals. The region represented, in 2017, an important part of the worldwide mining activity. Three principal types of deposits have been identified and studied: 1) porphyry type deposits extending from central Chile and Argentina to Bolivia, and Northern Peru, 2) iron oxide-copper-gold (IOCG) deposits, extending from central Peru to central Chile, and 3) epithermal tin polymetallic deposits extending from Southern Peru to Northern Argentina, which compose a large part of the deposits of the Bolivian Tin Belt (BTB). Deposits in the BTB can be divided into two major types: (1) tin-tungsten-zinc pluton-related polymetallic deposits, and (2) tin-silver-lead-zinc epithermal polymetallic vein deposits. Mina Pirquitas is a tin-silver-lead-zinc epithermal polymetallic vein deposit, located in north-west Argentina, that used to be one of the most important tin-silver producing mine of the country. It was interpreted to be part of the BTB and it shares similar mineral associations with southern pluton related BTB epithermal deposits. Two major mineralization events related to three pulses of magmatic fluids mixed with meteoric water have been identified. The first event can be divided in two stages: 1) stage I-1 with quartz, pyrite, and cassiterite precipitating from fluids between 233 and 370 °C and salinity between 0 and 7.5 wt%, corresponding to a first pulse of fluids, and 2) stage I-2 with sphalerite and tin-silver-lead-antimony sulfosalts precipitating from fluids between 213 and 274 °C with salinity up to 10.6 wt%, corresponding to a new pulse of magmatic fluids in the hydrothermal system. The mineralization event II deposited the richest silver ores at Pirquitas. Event II fluids temperatures and salinities range between 190 and 252 °C and between 0.9 and 4.3 wt% respectively. This corresponds to the waning supply of magmatic fluids. Noble gas isotopic compositions and concentrations in ore-hosted fluid inclusions demonstrate a significant contribution of magmatic fluids to the Pirquitas mineralization although no intrusive rocks are exposed in the mine area. Lead and sulfur isotopic measurements on ore minerals show that Pirquitas shares a similar signature with southern pluton related polymetallic deposits in the BTB. Furthermore, the major part of the sulfur isotopic values of sulfide and sulfosalt minerals from Pirquitas ranges in the field for sulfur derived from igneous rocks. This suggests that the main contribution of sulfur to the hydrothermal system at Pirquitas is likely to be magma-derived. The precise age of the deposit is still unknown but the results of wolframite dating of 2.9 ± 9.1 Ma and local structural observations suggest that the late mineralization event is younger than 12 Ma.

Description: Die zentralen Anden beherbergen große Reserven von unedlen und Edelmetallen. Die Region war 2017 ein wichtiger Teil der weltweiten Bergbautätigkeit. Bisher wurden drei Hauptlagerstätten identifiziert und untersucht: 1) Porphyr-Lagerstätten, die sich von Zentralchile und Argentinien bis Bolivien und Nord-Peru erstrecken; 2) Eisenoxid-Kupfer-Gold-Lagerstätten (IOCG), die sich von Zentralperu bis Zentralchile ausdehnen, sowie 3) polymetallische epithermale Zinnlagerstätten, die sich von Südperu bis nach Nordargentinien erstrecken und einen Großteil der Lagerstätten des bolivianischen Zinngürtels (Bolivian Tin Belt - BTB) bilden. Lagerstätten im BTB können in zwei Haupttypen unterteilt werden: (1) polymetallische Lagerstätten aus Zinn-Wolfram-Zink im Zusammenhang mit Plutonen und (2) polymetallische Zinn-Silber-Blei-zink Anlagerungen in epithermalen gangförmigen Lagerstätten. Mina Pirquitas ist eine epithermale Zinn-Silber-Blei-Zink-Polymetallvenenlagerstätte im Nordwesten Argentiniens, die früher eine der wichtigsten Zinnsilber-Mine meines Landes war. Es wurde als Teil der BTB interpretiert und hat ähnliche Mineralstoffverbände mit südlichen Pluton-bezogenen BTB-Epithermalvorkommen. Es wurden zwei bedeutende Mineralisierungsereignisse identifiziert, die sich auf drei mit meteorischem Wasser gemischte magmatische Fluide beziehen. Das erste Ereignis kann in zwei Stufen unterteilt werden: 1) Stufe I-1, wobei Quarz, Pyrit und Cassiterit aus Fluiden zwischen 233 und 370 ° C und einem Salzgehalt zwischen 0 und 7,5 Gew .-% ausfallen, entsprechend einem ersten Flüssigkeitsimpuls, und 2) Stufe I-2 mit Sphalerit und Zinn-Silber-Blei-Antimonsulfosalzen, die aus Fluiden zwischen 213 und 274 ° C mit einem Salzgehalt von bis zu 10,6 Gew .-% ausfallen, was einem neuen Impuls magmatischer Fluiden im hydrothermalen System entspricht. Durch die Mineralisierung II wurden die reichsten Silbererze bei Pirquitas abgelagert. Die Temperaturen und Salzgehalte von Event II liegen zwischen 190 und 252 ° C bzw. zwischen 0,9 und 4,3 Gew .-%. Dies entspricht der abnehmenden Versorgung mit magmatischen Fluiden. Edelgasisotopenzusammensetzungen und -konzentrationen in mit Erz beherbergten Flüssigkeitseinschlüssen zeigen einen signifikanten Beitrag magmatischer Fluiden zur Pirquitas-Mineralisierung, obwohl keine intrusiven Gesteine im Minengebiet exponiert sind. Messungen von Blei- und Schwefelisotopen an Erzmineralien zeigen, dass Pirquitas eine ähnliche Signatur mit südlichen Pluton-verwandten polymetallischen Lagerstätten in der BTB teilt. Darüber hinaus liegt der größte Teil der Schwefelisotopenwerte von Sulfid- und Sulfosaltmineralien aus Pirquitas im Bereich von Schwefel aus magmatischem Gestein. Dies deutet darauf hin, dass der Hauptbeitrag von Schwefel zum hydrothermalen System bei Pirquitas wahrscheinlich aus Magma stammt. Das genaue Alter der Lagerstätte ist noch nicht bekannt, aber die Ergebnisse der Wolframit-Datierung von 2,9 ± 9,1 Ma und lokalen Strukturbeobachtungen legen nahe, dass die späten Mineralisierungsereignisse jünger als 12 Ma sind.

Description: Several hydraulic fracturing tests were performed in boreholes located in central Hungary in order to determine the in-situ stress for a geological site investigation. At a depth of about 540 m, the observed pressure versus time curves in mica schist with low dip angle foliation shows atypical pressure versus time results. After each pressurization cycle, the fracture breakdown pressure in the first fracturing cycle is lower than the refracturing or reopening pressure in the subsequent pressurizations. It is assumed that the viscosity of the drilling mud and observed foliation of the mica schist have a significant influence on the pressure values. In order to study this problem, numerical modeling was performed using the distinct element code particle flow code, which has been proven to be a valuable tool to investigate rock engineering problems such as hydraulic fracturing. The two-dimensional version of the code applied in this study can simulate hydro-mechanically coupled fluid flow in crystalline rock with low porosity and pre-existing fractures. In this study, the effect of foliation angle and fluid viscosity on the peak pressure is tested. The atypical characteristics of the pressure behaviour are interpreted so that mud with higher viscosity penetrates the sub-horizontal foliation plane, blocks the plane of weakness and makes the partly opened fracture tight and increase the pore pressure which decreases slowly with time. We see this viscous blocking effect as one explanation for the observed increase in fracture reopening pressure in subsequent pressurization cycles.

Description: In this study we investigate the longitudinal variations in the mean densities of field-aligned currents (FACs) at high latitudes in different seasons, by using high resolution magnetic field data from SWARM A and C satellites. Longitudinal variations are about a factor of 1.2~3.2 larger in the Southern Hemisphere than in the Northern Hemisphere. A tidal analysis is applied to FACs. D0 and DW2 are the dominant non-migrating components. DW2 is larger than D0 in summer and equinox. The longitudinal variations in solar illumination can explain D0 wave in FACs, with more solar illumination at near pole longitudes than at far-from-pole longitude. Factors like the geomagnetic field strength and dipole tilt angle might contribute to the observed DW2 features in FACs. The FACs simulated by the global ionosphere and thermosphere model only show D0 wave. The theoretical study reveals that the role of neutral wind is comparable to that of the electric field in the formation of D0 wave.

Description: EnMAP (Environmental Mapping and Analysis Program, www.enmap.org) is a German, Earth observing, imaging spectroscopy, spaceborne mission planned for launch in 2020. The data products will cover the spectral range from 420 nm to 2450 nm with a spectral sampling distance between 5 and 12 nm with an expected signal-to-noise-ratio of 400:1 in the visible near-infrared and 180:1 in the shortwave infrared parts of the electro-magnetic spectrum. The resulting images will cover an area of 30 km in the across- track direction with a ground sampling distance of 30 m. The across-track tilt-capability of 30° enables revisit times of less than four days. The resulting data products will be freely available to the scientific user community for measuring, deriving, and analyzing diagnostic parameters, which describe vital processes on the Earth's surface comprising agriculture, forestry, soil and geological environments, as well as coastal zones and inland waters. This work concentrates on the description of activities performed and facilities involved for the preparation of these products. It starts out by the description of the User Portals for observation requests and acquisition planning, touches the aspects of creating the time-lines, the commanding and controlling of the satellite, the downlink of the telemetry and payload data, the design of the processing chain and the archiving of data plus a set of activities flanking the above for the provision of high-quality data products.

Description: In this study we derive the stress tensor and its local variations throughout the Marmara region, Turkey. Based on a recently compiled 10-year earthquake catalogue, we directly invert first-motion polarity data and quantify confidence intervals for the principal stress orientations. We find a combined strike-slip and normal faulting stress field for the Marmara region generally reflecting the overall transtensional setting. However, the results clearly show moderate local variations of the stress field. The largest (σ1) and intermediate (σ2) principal stresses show an average regional trend of N125∘E and locally varying plunges. The least principal stress (σ3) is well resolved in its confidence interval and consistent throughout the region with an average trend of ∼ N35∘E and a subhorizontal plunge. The eastern Sea of Marmara shows local stress field orientations with pronounced strike-slip (northern part) and normal faulting (southern part) components. Along the central Marmara region, normal faulting tends to dominate, while a well resolved strike-slip stress regime is found in the western Sea of Marmara region. Regarding the faulting mechanism of an earthquake with magnitude up to 7.4 which is expected in this area in direct vicinity of the Istanbul metropolitan region, our results imply that neither strike-slip nor normal faulting kinematics can be excluded.

Description: Satellite gravimetry allows for determining large scale mass transport in the system Earth and to quantify ice mass change in polar regions. We provide, evaluate and compare a long time-series of monthly gravity field solutions derived either by satellite laser ranging (SLR) to geodetic satellites, by GPS and K-band observations of the GRACE mission, or by GPS observations of the three Swarm satellites. While GRACE provides gravity signal at the highest spatial resolution, SLR sheds light on mass transport in polar regions at larger scales also in the pre- and post-GRACE era. To bridge the gap between GRACE and GRACE Follow-On, we also derive monthly gravity fields using Swarm data and perform a combination with SLR. To correctly take all correlations into account, this combination is performed on the normal equation level. Validating the Swarm/SLR combination against GRACE during the overlapping period January 2015 to June 2016, the best fit is achieved when down-weighting Swarm compared to the weights determined by variance component estimation. While between 2014 and 2017 SLR alone slightly overestimates mass loss in Greenland compared to GRACE, the combined gravity fields match significantly better in the overlapping time period and the RMS of the differences is reduced by almost 100 Gt. After 2017, both SLR and Swarm indicate moderate mass gain in Greenland.

Description: Adjustment of median ground motion prediction equations (GMPEs) from one region to another region is one of the major challenges within the current practice of seismic hazard analysis. In our approach of generating response spectra, we derive two separate empirical models for a) Fourier amplitude spectrum (FAS) and b) duration of ground motion. To calculate response spectra, the two models are combined within the random vibration theory (RVT) framework. The models are calibrated on recordings obtained from shallow crustal earthquakes in active tectonic regions. We use a subset of NGA-West2 database with M3.2–7.9 earthquakes at distances 0–300 km. The NGA-West2 database expanded over a wide magnitude and distance range facilitates a better constraint over derived models. A frequency-dependent duration model is derived to obtain adjustable response spectral ordinates. Excellent comparison of our approach with other NGA-West2 models implies that it can also be used as a stand-alone model.

Description: Deliverable D5.2 presents the experimental outcome of jetting experiments at simulated reservoir conditions. Different rock types are tested under various conditions with the use of three different types of test bench. At first jetting experiments are conducted under submerged conditions in order to derive a better understanding of the governing erosion mechanism. Therefore pitting tests are combined with PIV measurements in order to derive and explain the erosion pattern of the occurring cavitation erosion and why the rock is more like to be eroded by the stagnation pressure of the impinging jet. Second, jetting experiments under pressure controlled conditions are performed. Rate of penetrations (ROP) of up to 100 m/h can be achieved which proofs the successful application of RJD technology especially in sand stone reservoir rock types. Especially the rotating nozzle design bears the highest potential for jetting operations where the static nozzle designs tend to fail, especially when pore pressure increases. The third experimental series under application of a bi- axial stress field show that the current RJD technology, as being used by project partner WSG, is not able to penetrate harder sandstone rock types (e.g. Dortmund sandstone) when field operating conditions are applied. The induced stress in the specimen does not initiate or enhance ROP. A second experiment thereby shows that higher nozzle exit speeds can lead to massive breakouts. Fourth, experiments are performed under a tri-axial stress field in collaboration with TU DELFT. Rock cubes are tested under different and very severely stress regimes while jetting into them. Compared to tests at atmospheric conditions it can be stated that the application of a stress field does not enhance the erosion of rock. At last experiments are conducted with the project partner WSG in order to determine the jetability of the Icelandic Basalt rock type and Icelandic inter basalt sediment layer. The experiments show that already higher pump pressures result in higher jetting performance, hence making them jetable as previously not expected. Furthermore the experiments approved the feasibility of the planned field test in Iceland when the soft sediment layer is the target zone. All in all the experiments conducted with the RJD technology show different results at simulated reservoir conditions compared to those at atmospheric which are described in deliverable D5.1 (Hahn & Wittig, 2017). Therefor, further testing at conditions representing the reservoir conditions more closer are needed in order to better understand and analyze the jetting process downhole.

Description: In this deliverable, the objectives of the Imperial College team are to consider jetted boreholes in the context of conventional borehole wall-rock stability analysis and to utilise an in-house advanced combined finite-discrete element code to examine the wall-rock failure process for jetted holes. The geomechanical modelling of Lateral Stability in D7.2 presented here is in addition to the main focus on modelling the water-jetting breakdown of the rock itself, reported in D7.1.

Description: The aim of this research is to investigate the failure mechanism for different types of rock in the context of water jet drilling and to predict the jet-ability or assess the radial jet drilling (RJD) performance prior to drilling and at the well petrophysical analysis stage. The main approach is to numerically simulate the water jet drilling for different types of rock using ICL’s in-house fluid-solid coupling codes. The rock properties, CT-scan data and jetting results obtained from D4.1 (Bakker et al., 2018) and D5.1 (Hahn et al., 2017) provide a good foundation for the related numerical results.

Description: Satellite remote sensing has been widely used in the last decades for agricultural applications, both for assessing vegetation condition and for subsequent yield prediction. Existing remote sensing-based methods to estimate gross primary productivity (GPP), which is an important variable to indicate crop photosynthetic function and stress, typically rely on empirical or semi-empirical approaches, which tend to over-simplify photosynthetic mechanisms. In this work, we take advantage of all parallel developments in mechanistic photosynthesis modeling and satellite data availability for an advanced monitoring of crop productivity. In particular, we combine process-based modeling with the soil-canopy energy balance radiative transfer model (SCOPE) with Sentinel-2 and Landsat 8 optical remote sensing data and machine learning methods in order to estimate crop GPP. With this approach, we by-pass the need for an intermediate step to retrieve the set of vegetation biophysical parameters needed to accurately model photosynthesis, while still accounting for the complex processes of the original physically-based model. Several implementations of the machine learning models are tested and validated using simulated and flux tower-based GPP data. Our final neural network model is able to estimate GPP at the tested flux tower sites with r2 of 0.92 and RMSE of 1.38 gC d−1 m−2, which outperforms empirical models based on vegetation indices. The first test of applicability of this model to Landsat 8 data showed good results (r2 of 0.82 and RMSE of 1.97 gC d−1 m−2), which suggests that our approach can be further applied to other sensors. Modeling and testing is restricted to C3 crops in this study, but can be extended to C4 crops by producing a new training dataset with SCOPE that accounts for the different photosynthetic pathways. Our model successfully estimates GPP across a variety of C3 crop types and environmental conditions even though it does not use any local information from the corresponding sites. This highlights its potential to map crop productivity from new satellite sensors at a global scale with the help of current Earth observation cloud computing platforms.

Description: After developing a wind speed retrieval algorithm, derived winds from measurements of UK TechDemoSat-1 (TDS-1), from May 2015 to July 2017, are compared to wind products of Advanced Scatterometer showing a reliable performance, especially during rain events. However, a rain signature in GNSS-R observations, a decrease in the value of the bistatic radar cross section at low winds, is demonstrated, which can potentially enable the technique to detect precipitation over oceans induced by low-to-moderate winds. This phenomenon is investigated and finally characterized as the rain splash effect altering the ocean surface roughness. To improve the quality of derived winds, a machine learning technique is implemented for the wind speed inversion as a geophysical model function. The trained feedforward neural network shows a significant improvement of 17% in the wind speed RMSE compared to the LS approach. In the end, one can conclude that space-borne ocean monitoring is evolving existing products with a potential for novel geophysical applications.

Description: The climate is a complex dynamical system involving interactions and feedbacks among different processes at multiple temporal and spatial scales. Although numerous studies have attempted to understand the climate system, nonetheless, the studies investigating the multiscale characteristics of the climate are scarce. Further, the present set of techniques are limited in their ability to unravel the multi-scale variability of the climate system. It is completely plausible that extreme events and abrupt transitions, which are of great interest to climate community, are resultant of interactions among processes operating at multi-scale. For instance, storms, weather patterns, seasonal irregularities such as El Niño, floods and droughts, and decades-long climate variations can be better understood and even predicted by quantifying their multi-scale dynamics. This makes a strong argument to unravel the interaction and patterns of climatic processes at different scales. With this background, the thesis aims at developing measures to understand and quantify multi-scale interactions within the climate system. In the first part of the thesis, I proposed two new methods, viz, multi-scale event synchronization (MSES) and wavelet multi-scale correlation (WMC) to capture the scale-specific features present in the climatic processes. The proposed methods were tested on various synthetic and real-world time series in order to check their applicability and replicability. The results indicate that both methods (WMC and MSES) are able to capture scale-specific associations that exist between processes at different time scales in a more detailed manner as compared to the traditional single scale counterparts. In the second part of the thesis, the proposed multi-scale similarity measures were used in constructing climate networks to investigate the evolution of spatial connections within climatic processes at multiple timescales. The proposed methods WMC and MSES, together with complex network were applied to two different datasets. In the first application, climate networks based on WMC were constructed for the univariate global sea surface temperature (SST) data to identify and visualize the SSTs patterns that develop very similarly over time and distinguish them from those that have long-range teleconnections to other ocean regions. Further investigations of climate networks on different timescales revealed (i) various high variability and co-variability regions, and (ii) short and long-range teleconnection regions with varying spatial distance. The outcomes of the study not only re-confirmed the existing knowledge on the link between SST patterns like El Niño Southern Oscillation and the Pacific Decadal Oscillation, but also suggested new insights into the characteristics and origins of long-range teleconnections. In the second application, I used the developed non-linear MSES similarity measure to quantify the multivariate teleconnections between extreme Indian precipitation and climatic patterns with the highest relevance for Indian sub-continent. The results confirmed significant non-linear influences that were not well captured by the traditional methods. Further, there was a substantial variation in the strength and nature of teleconnection across India, and across time scales. Overall, the results from investigations conducted in the thesis strongly highlight the need for considering the multi-scale aspects in climatic processes, and the proposed methods provide robust framework for quantifying the multi-scale characteristics.

Description: Das Klima ist ein komplexes Zusammenspiel verschiedener Mechanismen und Rückkopplungen auf mehreren zeitlichen und räumlichen Skalen. Viele Studien beschäftigten sich mit dem diesem System, nur wenige jedoch konzentrierten sich auf das Multiskalenverhalten des Klimas. Vor allem die bis dato verfügbaren Techniken schränkten eine vertiefte Analyse der Klimavariabilität auf unterschiedlichen Skalen ein. Von großen Interesse in der aktuellen Klimaforschung sind Extremereignisse und plötzliche Veränderungen, welche höchstwahrscheinlich aus dem Zusammenwirken von Prozessen auf unterschiedlichen Skalen hervorgehen. Um Stürme, wiederkehrende Wetterlagen, jahreszeitliche Phänomene wie El Niño, Fluten, Dürren oder Klimaschwankungen über Jahrzehnte besser zu verstehen oder sogar vorhersagen zu können, müssen wir deren Dynamik auf unterschiedlichen Skalen quantifizieren. In der vorliegenden Arbeit werden Mittel und Wege präsentiert um das Zusammenwirken auf verschiedenen Skalen im Klimasystem besser zu verstehen und zu quantifizieren. Im ersten Teil dieser Arbeit stelle ich zwei Methoden, multi-scale event synchronization (MSES) und wavelet multi-scale correlation (WMC) vor, welche skalenspezifischen Eigenschaften in klimatischen Prozessen abbilden. Die vorgestellte Methode wurde mit mehreren synthetischen und realen Zeitreihen getestet um ihre Anwendbarkeit und Reproduzierbarkeit zu überprüfen. Die Ergebnisse zeigen, dass beide Methoden Beziehungen auf unterschiedlichen zeitlichen Skalen detaillierter als traditionelle Ansätze abbilden können. Im zweiten Teil dieser Arbeit bilde ich klimatische Netzwerke mithilfe eines Maßes zur Ähnlichkeit auf Multiskalen. Dabei untersuche ich die Entwicklung von räumlichen Beziehungen um klimatische Prozesse auf mehreren Zeitskalen zu verstehen. Die Methoden WMC und MSES werden zusammen mit komplexen Netzwerken auf zwei Datensätze angewendet. In der ersten Anwendung werden klimatische Netzwerke mit WMC für univariate globale Meeresoberflächentemperaturen gebildet. Auf unterschiedlichen Zeitskalen sollen dabei kurze und lange Fernwirkungen, welche andernfalls auf einer einzigen Zeitskale unerkannt blieben, entdeckt werden. In diesem Klimanetzwerk ließ sich eine starke Variabilität über die Zeit feststellen, was auf eine skalenfreie und kleinräumige Netzstruktur auf großem, beziehungsweise kleinem Maßstab schließen lässt. Weitere Untersuchungen von Klimanetzwerken auf unterschiedlichen Zeitskalen zeigte (i) hohe Variabilität und Co-Variabilität in Regionen, und (ii) Fernbeziehungen auf kurzen und langen Entfernungen mit variabler räumlicher Distanz. Die Ergebnisse bestätigen bekannte physikalischen Wechselwirkungen und daher auch die Stärken meines Ansatzes. Dadurch ergeben sich neue Einblicke in die Klimatologie von Ozeanen, sodass beispielsweise konvektive Prozesse in der Atmosphäre eine Abhängigkeit über weite Entfernungen aufweisen können. In der zweiten Anwendung verwendeten wir das von mir entwickelte, nicht-lineare MSES Ähnlichkeitsmaß um multivariate Fernbeziehungen zwischen Starkniederschlägen und klimatischen Mustern über Indien zu quantifizieren. Unsere Ergebnisse bestätigen signifikante, nicht-lineare Einflüsse, welche von traditionellen Methoden bisher unzureichend abgebildet wurden. Des Weiteren fanden wir deutliche Schwankungen in der Stärke und in der Ausprägung von Fernbeziehungen über Indien und über Zeitskalen. Zusammenfassend zeigen die Ergebnisse dieser Fallstudien, dass Multiskalen in Klimaprozessen entschieden berücksichtigt werden müssen und dass der entwickelte methodische Rahmen adäquat die charakteristischen Prozesse quantifizieren kann.

Description: The C-band synthetic aperture radar (SAR) satellites of Sentinel-1 with capability to obtain acquisition in Terrain Observation with Progressive Scan (TOPS) mode have brought new opportunities for large-scale monitoring of the ground surface deformation using interferometric SAR (InSAR) technique. However, despite the potential to generate large-scale interferograms, the highly spatiotemporal variability in troposphere, limits InSAR measurements accuracy. In addition, the measurement accuracy might be degraded by the signals due to the ionosphere, which is not negligible even at C-band data. One way for the atmospheric delay correction in interferograms is using external sources such as the global navigation satellite system (GNSS). The total electron content (TEC) and the zenith total delay (ZTD) values measured from a dense network of the GNSS receivers can be used to retrieve the ionospheric and tropospheric contributions to the interferometric phase, respectively. However, interpolation of the data is a big challenge, as we need to find a suitable function to predict the delay for the whole interferogram, which is challenging for large-scale Sentine-1 interferograms. In this study, we propose a new technique based on machine learning (ML) regression approach using the combination of small-baseline interferograms and the GNSS derived TEC and ZTD values to mitigate the atmospheric contributions. The technique produces the differential atmospheric (using the TEC and ZTD values) map for short-interval intergerograms based on the phase-atmosphere relation by this assumption that the deformation contribution to the interferometric phase is negligible in the short intervals. It then estimates the differential atmospheric maps for the longer-interval interferograms using the atmospheric maps with short intervals. The technique facilitates the corrections, as we do not need to deal with finding a suitable function for interpolation of distributed external observations. We implement our method on 12 concatenated frames of Sentinel-1 images acquired between May-October 2016 along a track over Norway to correct the interferograms from the atmospheric effects. Then, we apply the small baseline subset (SBAS) approach on the atmospherically corrected interferograms. The results on the stack of large-scale Sentinel-1 interferograms show that the ML-based method largely removes the ionospheric and tropospheric effects and thus improves the InSAR time series analysis results. To validate the results we compare the displacement time-series derived by small-baseline interferograms corrected by our method with the displacement time-series observed by GNSS receivers.

Description: In a first aspect, a method for monitoring a material and/or a device in a borehole using a fiber optic measurement cable is provided, and, in a second aspect, a system for carrying out the method is provided. The system includes a fiber optic measurement cable which is present introduced into a borehole, wherein a material and a device are present in the borehole

Description: Calcium sulfate minerals are found in nature as three hydrates: gypsum (CaSO4·2H2O), bassanite (CaSO4·0.5H2O), and anhydrite (CaSO4). Due to their relevance in natural and industrial processes, the formation pathways of calcium sulfates from aqueous solution have been the subject of intensive research, and there is a growing body of literature, suggesting that calcium sulfates form through nonclassical nanoparticle-mediated crystallization processes. We showed earlier (Stawski et al. Nat. Commun.2016, 7, 11177) that at the early stages in the precipitation reaction, calcium sulfate nanocrystals nucleate through the reorganization and coalescence of aggregates rather than through classical unit addition. Here, we used low-dose dark field (DF) transmission electron microscopy (TEM) and electron diffraction and document that these restructuring processes do not continue until a final near-perfectly homogeneous single crystal is obtained. Instead, we show that the growth process yields a final imperfect mesocrystal with an overall morphology resembling that of a single crystal, yet composed of smaller nanodomains. Our data reveal that organic-free calcium sulfate mesocrystals grown by a particle mediated-pathway may preserve in the final crystal structure a “memory” or “imprint” of their nonclassical nucleation process, something that has been overlooked until now. Furthermore, the nanoscale misalignment of the structural subunits within these crystals might propagate through the length-scales, which is potentially expressed macroscopically as misaligned zones/domains in large single crystals. This is akin to observations in some of the giant crystals from the Naica Mine, Chihuahua, Mexico.

Description: Jasmine Kaur Sandhu, Maria-Theresia Walach, Hayley Allison and Clare Watt report on the RAS meeting The Global Response of the Terrestrial Magnetosphere during Storms and Substorms.

Description: Abstract Observations of the electron radiation belts have shown links between increases in the low-energy seed population and enhancements in the 〉1-MeV flux. During active times, low-energy electrons are introduced to the radiation belt region before being accelerated to higher energies via a range of mechanisms. The impact of variations in the seed population on the 1-MeV flux level were explored using the British Antarctic Survey Radiation Belt Model. We find that, for a period from the 21 April to 9 May 2013, the increase in the low-energy electron flux was vital to recreate the observed 1-MeV flux enhancement on the 1 May but was less important for the 1-MeV enhancement on the 27 April 2013. To better understand the relationships between the different energy populations, a series of idealized experiments with the 2-D British Antarctic Survey Radiation Belt Model were performed, which highlight a careful balance between losses and acceleration from chorus waves. Seed population enhancements alter this balance by increasing the phase space density gradient, and consequently, the rate of energy diffusion, allowing acceleration to surpass loss. Additionally, we demonstrate that even with the same chorus diffusion coefficients and the same low-energy boundary condition, the flux of ∼500-keV to 1-MeV electrons increased when starting with a hard spectrum but decreased for a soft initial spectrum. This suggests that initial energy gradients in the phase space density were important to determine whether 〉500-keV electrons were enhanced due to chorus wave acceleration.

Description: The experimental measurement of frame-dragging or the Lense-Thirring (LT) effect based on Satellite Laser Ranging (SLR) observations to the LAGEOS satellites was successfully demonstrated with an accuracy of about 10%. Here we look in detail into the effect of the node drift induced by the time variable part of the C(2,0) term of the gravity field model describing the flattening of the Earth. We demonstrate that errors in C(2,0) can effectively be taken care of by analyzing two satellites for the LT measurement. We also adopt some recent gravity field models in order to independently repeat and extend the LT experiments so far. The gravity field models used for this are derived either partly depending on LAGEOS SLR observations or completely independent from LAGEOS, and based on dedicated gravity field satellite missions like CHAMP, GRACE and GOCE. It turns out that from all the gravity field models tested the claimed accuracy of 10% of the LT measurement can be confirmed.

Description: The Internet and the expansion of digital technology have opened up new opportunities for the dissemination and exchange of knowledge and information for science. In addition to the concepts of Open Science and Open Access, the accessibility and reusability of research data have become sources of debate. Peter Schirmbacher has focused in his research and teaching on the relevance, design and use of information infrastructures for research data in the digital age. Schirmbacher has made pioneering contributions to development of these services for the benefit of scientific activities. This contribution provides an overview of these information infrastructures and their potential, and situates them in the current context of Open Science debates.

Description: Understanding the gypsum (CaSO4·2H2O) formation pathway from aqueous solution has been the subject of intensive research in the past years. This interest stems from the fact that gypsum appears to fall into a broader category of crystalline materials whose formation does not follow classical nucleation and growth theories. The pathways involve transitory precursor cluster species, yet the actual structural properties of such clusters are not very well understood. Here, we show how in situ high-energy X-ray diffraction experiments and molecular dynamics (MD) simulations can be combined to derive the structure of small CaSO4 clusters, which are precursors of crystalline gypsum. We fitted several plausible structures to the derived pair distribution functions and explored their dynamic properties using unbiased MD simulations based on both rigid ion and polarizable force fields. Determination of the structure and (meta)stability of the primary species is important from both a fundamental and applied perspective; for example, this will allow for an improved design of additives for greater control of the nucleation pathway.

Description: Central European climate is strongly influenced by North Atlantic (Westerlies) and Siberian High circulation patterns, which govern precipitation and temperature dynamics and induce heterogeneous climatic conditions, with distinct boundaries between climate zones. These climate boundaries are not stationary and shift geographically, depending on long-term atmospheric conditions. So far, little is known about past shifts of these climate boundaries and the local to regional environmental response prior to the instrumental era. High resolution multi-proxy data (stable oxygen and carbon isotope ratios, S/Ca and Sr/Ca) from two Holocene stalagmites from Bleßberg Cave (Thuringia) are used here to differentiate local and pan-regional environmental and climatic conditions Central Germany through the Holocene. Carbon isotope and S/Ca and Sr/Ca ratios inform us on local Holocene environmental changes in and around the cave, while δ18O (when combined with independent records) serves as proxy for (pan-)regional atmospheric conditions. The stable carbon isotope record suggests repeated changes in vegetation density (open vs. dense forest), and increasing forest cover in the late Holocene. Concurrently, decreasing S/Ca values indicate more effective sulfur retention in better developed soils, with a stabilization in the mid-Holocene. This goes in hand with changes in effective summer infiltration, reflected in the Sr/Ca profile. Highest Sr/Ca values between 4 ka and 1 ka BP indicate intensified prior calcite precipitation resulting from reduced effective moisture supply. The region of Bleßberg Cave is sensitive to shifts of the boundary between maritime (Cfb) and continental (Dfb) climate and ideally suited to reconstruct past meridional shifts of this divide. We combined the Bleßberg Cave δ18O time series with δ18O data from Bunker Cave (western Germany) and a North Atlantic Oscillation (NAO) record from lake SS1220 (SW Greenland) to reconstruct the mean position of the Cfb-Dfb climate boundary. We further estimate the dynamic interplay of the North Atlantic Oscillation and the Siberian High and their influence on Central European climate. Repeated shifts of the Cfb-Dfb boundary over the last 4000 years might explain previously observed discrepancies between proxy records from Europe. Detailed correlation analyses reveal multi-centennial scale alternations of maritime and continental climate and, concurrently, waning and waxing influences of Siberian High and NAO on Central Europe.

Description: GRACE/GRACE-FO Level-3 product based on GFZ RL06 Level-2B products (Dahle & Murböck, 2019) representing Ocean Bottom Pressure (OBP) variations provided at 1° latitude-longitude grids as defined over ocean areas. The OBP grids are provided in NetCDF format divided into yearly batches. The files each contain seven different variables: 1) 'barslv': gravity-based barystatic sea-level pressure 2) 'std_barslv': gravity-based barystatic sea-level pressure uncertainties 3) 'resobp': gravity-based residual ocean circulation pressure resobp 4) 'std_resobp': gravity-based residual ocean circulation pressure uncertainties 5) 'leakage': apparent gravity-based bottom pressure due to continental leakage 6) 'model_ocean': background-model ocean circulation pressure 7) 'model_atmosphere': background-model atmospheric surface pressure These Level-3 products are visualized at GFZ's web portal GravIS (http://gravis.gfz-potsdam.de). Link to data products: ftp://isdcftp.gfz-potsdam.de/grace/GravIS/GFZ/Level-3/OBP

Description: The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides real-time seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. Like all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.

Description: Advancements in the Global Geodetic Observing System (GGOS) have enabled us to investigate the effects of lateral heterogeneities in the internal Earth structure on long-term surface deformations caused by the Glacial Isostatic Adjustment (GIA). Many theories have been developed so far to consider such effects based on analytical and numerical approaches, and 3D viscosity distributions have been inferred. On the other hand, fewer studies have been conducted to assess the effects of lateral heterogeneities on short-term, elastic deformations excited by surface fluids, with 1D laterally homogeneous theories being frequently used. In this paper, we show that a spectral finite-element method is applicable to calculate the elastic deformation of an axisymmetric spherical Earth. We demonstrate the effects of laterally heterogeneous moduli with horizontal scales of several hundred kilometers in the upper mantle on the vertical response to a relatively large-scale surface load. We found that errors due to adopting a 1D Green’s function based on a local structure could amount to 2–3% when estimating the displacement outside the heterogeneity. Moreover, we confirmed that the mode coupling between higher-degree spherical harmonics needs to be considered for simulating smaller-scale heterogeneities, which agreed with results of previous studies.

Description: One of the lowest geoid anomalies on Earth lies in the Indian Ocean just south of the Indian peninsula. Several theories have been proposed to explain this negative geoid anomaly, most of which invoke past subduction. Some recent studies have argued that high-velocity anomalies in the lower mantle coupled with low-velocity anomalies in the upper mantle are responsible for these geoid lows. However, there is no general agreement regarding the source of the geoid low in the Indian Ocean. We investigate the source of this anomaly by using instantaneous models of density-driven mantle convection. Our study is the first to successfully explain the presence of this anomaly using a global convection model driven by present-day density anomalies derived from seismic tomography. We test various tomography models in our flow calculations using different radial and lateral viscosity variations. Although quite a few of them produce a fairly high correlation to the observed geoid globally, only a few (SMEAN2, GyPSuM, SEMUCB, and LLNL-JPS) could match the exact location and pattern of the geoid low in the Indian Ocean. The source of this low is a low-density anomaly stretching from a depth of 300 km down to ∼900 km in the northern Indian Ocean region. This density anomaly potentially originates from plume material rising along the edge of the African Large Low Shear Velocity Province, which moves toward the northeast, along with the movement of the Indian plate in the same direction.

Description: Volcanic and seismic activities produce a variety of phenomena that put population at risk. In order to assess the seismic and volcanic hazard, many instruments are deployed around active volcanoes and seismic fault zones. Their records are useful to observe the activity of the volcanoes and faults in order to understand better their behaviour and issue warnings to authorities in charge of the public security. In this study, we used optical cables around Etna volcano to observe seismic and pressure signals associated with volcanic activity. The 2018 expedition consisted of three experiments. Firstly, we used a 4-km long telecom line in Zafferana and recorded all geodynamic and other activities for about 20 days. At this site, the fibre is known to cross active faults that are linked to the eastern volcano flank slowly sliding towards the sea. Secondly, we tested a 40 km-long cable from an internet provider at the western side of the volcano. Thirdly, we used a fibre cable deployed at the summit area of the volcano to test its ability to detect small volcanic events. In each of the three parts, a DAS system (iDASTM interrogator provided by Silixa) sent repeatedly coherent light pulses with a gauge length of 10 m and deduced the strain rate from interferometric measurements of the back-scattered light. We were able to measure every 2 metres the strain rate associated with several volcanic event types, earthquakes and many other signals from human activity. We validated the optical records with records from additional sensors such as seismic broadband stations, geophones and infrasound sensors. We present results from all experiments.

Description: In natural coastal wetlands, high supplies of marine sulfate suppress methanogenesis. Coastal wetlands are, however, often subject to disturbance by diking and drainage for agricultural use and can turn to potent methane sources when rewetted for remediation. This suggests that preceding land use measures can suspend the sulfate-related methane suppressing mechanisms. Here, we unravel the hydrological relocation and biogeochemical S and C transformation processes that induced high methane emissions in a disturbed and rewetted peatland despite former brackish impact. The underlying processes were investigated along a transect of increasing distance to the coastline using a combination of concentration patterns, stable isotope partitioning, and analysis of the microbial community structure. We found that diking and freshwater rewetting caused a distinct freshening and an efficient depletion of the brackish sulfate reservoir by dissimilatory sulfate reduction (DSR). Despite some legacy effects of brackish impact expressed as high amounts of sedimentary S and elevated electrical conductivities, contemporary metabolic processes operated mainly under sulfate-limited conditions. This opened up favorable conditions for the establishment of a prospering methanogenic community in the top 30–40 cm of peat, the structure and physiology of which resemble those of terrestrial organic-rich environments. Locally, high amounts of sulfate persisted in deeper peat layers through the inhibition of DSR, probably by competitive electron acceptors of terrestrial origin, for example Fe(III). However, as sulfate occurred only in peat layers below 30–40 cm, it did not interfere with high methane emissions on an ecosystem scale. Our results indicate that the climate effect of disturbed and remediated coastal wetlands cannot simply be derived by analogy with their natural counterparts. From a greenhouse gas perspective, the re-exposure of diked wetlands to natural coastal dynamics would literally open up the floodgates for a replenishment of the marine sulfate pool and therefore constitute an efficient measure to reduce methane emissions.

Description: We propose to investigate the structure and evolution of the Main Pamir Thrust (MPT) with a high-density seismological array. The MPT, with its surface expression along the east-west trending Alai Valley, marks the northern boundary of the Pamir. The Alai Valley, separating the Pamir and the Tien Shan, constitutes the last vestige of a formerly continuous basin that linked the Tarim and the Tajik Basins. The MPT manifests itself as a place of high seismic activity with frequently occurred disastrous earthquakes. The array is about 50 km long, consisted of 90 three-component geophones (stations G?? and C??) and 10 Trillium-Compact seismometers (stations T??), and equipped with 100 CUBE dataloggers. We will construct a high-resolution receiver function profile to image the MPT and accurately locate the local earthquakes associated with the MPT. Funded by BMBF, within the framework of CaTeNA project – Climatic and Tectonic Natural Hazards in Central Asia. Waveform data are available from the GEOFON data centre, under network code 7A and are embargoed until Jan 2024.

Description: Despite its unique properties the diffracted seismic wavefield is still rarely exploited in common practice. Although the first works on seismic diffraction date back at least as far as the 1950s, a first rigorous theoretical framework for diffraction imaging only evolved decades later and many important questions still remain unanswered until the present day. While this comparably slow progression can partly be explained by the lack of densely sampled high quality recordings, recent advances in acquisition and dedicated processing suggest we might be at the door step to a paradigm shift in which seismic diffraction could play an important role. Despite the fact that most major progress—in terms of data acquisition and processing—has been achieved for the reflected wavefield, upon closer inspection it becomes obvious that the concept of diffraction is deeply ingrained in migration-type seismic imaging. With the aim of complementing existing contributions on the topic, this chapter is an attempt to provide an intuitive introduction to the process of seismic diffraction. Discussed are the deep conceptual roots in optics, physical links to the Kirchhoff integral as well as diffraction types and their importance in different contexts of application. By means of controlled synthetic and academic as well as industry-scale field data examples, I suggest a simple integrated framework for noninvasive diffraction separation and high-resolution imaging, which remains computationally affordable and can be reproduced by the reader. Different applications suggest that the faint diffracted background wavefield is surprisingly rich and, once it is given a voice, it announces highly resolved features such as faults, fractures, and erosional unconformities, which remain notoriously hard to image conventionally. Extending the dominant theme of high-resolution seismic imaging, I illustrate how the superior illumination due to the uniform radiation of diffraction carries the additional potential for drastically reduced acquisitions and discuss the possibility of a systematic extraction of inter-scatterer traveltimes from coda waves.

Description: Glacial-isotactic adjustment (GIA) is one of the key processes considering relative sea-level (RSL) and paleo-topography during the last glacial cycle. Especially in former ice-covered regions the subsidence of the solid Earth due to ice loads can reach more than 500 m and contributes to the stability of ice-sheets (e.g. position of grounding line and ice-sheet elevation), whereas at the coasts of the world oceans the deformation is governed by global RSL fall of more than 100 m. Because the viscoelastic response of the solid Earth is governed by its viscosity structure, the effect of lateral viscosity variations on deformations due to GIA has to be estimated. The importance was already shown for the differences in earth structure below the glacial ice sheets of Fennoscandia and Laurentide, as well as for a number of peripheral and far-field regions. One open question arises: Can the 3D earth properly be parameterized by locally optimized 1D earth structures? In this study, we apply a 3D Earth structure which we derived from seismic tomography and further geodynamic constraints as an a priori estimation of the Earth viscosity distribution. Applying a standard glaciation history, we compare the response characteristics of 1D and 3D earth parameterizations and discuss the limits of optimized 1D earth parametrizations. We will focus on reconstructions of RSL during the last deglaciation in view of sea level index points which are generally used for validating the GIA process.

Description: Global geoidal undulations are often used as the constraining parameter to model the mantle convection pattern, while gravity data are typically applied to interpret the lithospheric structure. In more recent studies, especially after launching the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite gravity-gradiometry mission, gravity gradient measurements have also been used in various geoscience applications. The main motivation of using gravity gradients is to provide a more conclusive information about a spatial localization of investigated phenomena. In geophysical studies, such implications are particularly related to a probably better detection of investigated lithospheric structures, such as active tectonic margins. In this study, we address this aspect by comparing interpretational characteristics from gravity and gravity gradient information. The Bouguer and mantle gravity gradients are used for this purpose to interpret the lithospheric structure beneath the Indian Ocean as well as the (adjacent) continental lithospheric structures (such as the East African Rift System). Our results confirm that gravity gradient more closely reproduces some tectonic and volcanic features, such as oceanic subductions, volcanic island arcs, and convergent continental tectonic margins. Similarly, mid-oceanic spreading ridges are localized slightly better in the gravity gradient map. Our findings also indicate that the interpretational quality cannot be improved by using directly observed gravity gradients. The reason is that these interpretations require applying gravimetric forward modelling techniques in order to enhance a particular lithospheric structure.

Description: Enclosed topographic depressions are characteristic of karst landscapes on Earth. The developmental relationship between depression types, such as sinkholes (dolines) and uvalas, has been the subject of debate, mainly because the long developmental timescales in classical limestone karst settings impede direct observation. Here we characterize the morphometric properties and spatio-temporal development of ∼1150 sinkholes and five uvalas formed from ∼1980 to 2017 in an evaporite karst setting along the eastern coast of the hypersaline Dead Sea (at Ghor Al-Haditha, Jordan). The development of sinkhole populations and individual uvalas is intertwined in terms of onset, evolution and cessation. The sinkholes commonly develop in clusters, within which they may coalesce to form compound or nested sinkholes. In general, however, the uvalas are not defined by coalescence of sinkholes. Although each uvala usually encloses several clusters of sinkholes, it develops as a larger-scale, gentler and structurally distinct depression. The location of new sinkholes and uvalas shows a marked shoreline-parallel migration with time, followed by a marked shoreline-perpendicular (i.e. seaward) growth with time. These observations are consistent with theoretical predictions of karstification controlled by a laterally migrating interface between saturated and undersaturated groundwater, as induced by the 35 m fall in the Dead Sea water level since 1967. More generally, our observations indicate that uvalas and the sinkhole populations within them, although morphometrically distinct, can develop near-synchronously by subsidence in response to subsurface erosion.

Description: Low‐rate (15 s) and high‐rate (1 s) Global Positioning System (GPS) solutions were employed to investigate the coseismic deformation associated with the 23 January 2018 Mw 7.9 Kodiak, Alaska, offshore earthquake. The coseismic displacements of kinematic (high‐rate observations) and quasi‐kinematic (2 hr of low‐rate observations after the earthquake) GPS solutions are consistent with those derived from static GPS daily solutions, and all three sets conform to the characteristics of a strike‐slip earthquake. A comparison between the static and quasi‐kinematic results suggests that postseismic deformation within the first four days was negligible. We inverted the static displacement field for the slip in a five‐segment model and inferred that the largest slip occurred on right‐lateral south‐southeast‐striking (2.27 m) and left‐lateral northeast‐striking (2.42 m) fault segments. The inverted geodetic moment is M09.66×1020  N⋅m (⁠Mw 7.92). The nine‐month postseismic horizontal displacements at 12 nearby GPS sites we studied are 〈1  cm⁠, and the maximum postseismic deformation is 7.4 mm at site AC26. The postseismic transient was fit slightly better by a logarithmic model with a decay time of 6.4 days than by an exponential model with a decay time of 75.0 days. The postseismic deformation can be explained well by afterslip and/or viscoelastic relaxation.

Description: The CNES/GRGS RL04 Earth gravity models are a set of gravity field solutions based on GRACE and SLR data, provided at different time samplings: (A) CNES/GRGS RL04 time series (A/1) A monthly GRACE+SLR time series of gravity field models (A/2) A 10-day GRACE+SLR time series of gravity field models (B) A mean gravity model EIGEN-GRGS.RL04.MEAN-FIELD, computed from the monthly RL04 GRACE+SLR time series and from GOCE data. (A) CNES/GRGS RL04 time series DATA: The data from the Star Camera Assembly (SCA), Accelerometer (ACC), K-Band Ranging (KBR) and GPS receiver are used. The KBR data is processed in the form of the relative velocity between the spacecrafts: K-Band Range-Rate (KBRR). In addition to the data from GRACE, the data from 5 SLR satellites are also used (Lageos, Lageos-2, Starlette, Stella and Ajisai), in order to provide an accurate and consistent description of the very low degrees of the gravity field (mainly degrees 1 and 2). The version of the GRACE data used for RL04 is L1B-v2 for the ACC and GPS data, L1B-v3 for the SCA and KBR data. INVERSION METHOD: By contrast with the GRACE solutions in spherical harmonics provided by other groups, the CNES/GRGS solutions are not obtained by a simple Cholesky inversion. The normal matrices are first diagonalized, ordered by decreasing order of the Eigen values and only the best defined sets of linear combinations of the spherical harmonics are solved. More details can be found here: https://grace.obs-mip.fr/variable-models-grace-lageos/grace-solutions-release-04/rl04-products-description/ (B) EIGEN-GRGS.RL04.MEAN-FIELD mean model EIGEN-GRGS.RL04.MEAN-FIELD is a mean model of Earth's gravity field spherical harmonics coefficients, based on the RL04 version of the CNES/GRGS time series of monthly gravity field determinations from GRACE & SLR data. EIGEN-GRGS.RL04.MEAN-FIELD is complete to degree and order 300. Between degrees 1 and 90, it contains time-variable gravity (TVG) coefficients ; above degree 90, it is a static field. EIGEN-GRGS.RL04.MEAN-FIELD is based on GOCE-DIR5 for the part between degree 91 and 300. The TVG coefficients between degrees 1 and 90 are obtained from a regression on the GRGS-RL04-v1 monthly time series of solutions (2002/09 – 2016/06). For degrees 1 and 2 this TVG part is temporally extended to 1993/01-2019/02 through the use of a GRGS SLR-only solution based on the data of 5 SLR satellites (Lageos, Lageos-2, Starlette, Stella, Ajisai). Outside of the measurements period (1993/01-2019/02 for degrees 1 and 2, 2002/09-2016/06 for degrees 3 to 90), the gravity field is extrapolated in the following way: - for degrees 1 and 2, before 1993/01 : average slope based on historical SLR data, mean annual and semi-annual periodic signals based on their average value between 1993 and 2019 - for degrees 1 and 2, after 2019/02 : average slope & mean annual and semi-annual periodic signals (based on their average value between 1993 and 2019) - for degrees 3 to 90, before 2002/09 : zero-slope extrapolation, mean annual and semi-annual periodic signals based on their average value between 2002 and 2016 - for degrees 3 to 90, after 2016/06 : average slope & mean annual and semi-annual periodic signals (based on their average value between 1993 and 2019) More details can be found here: https://grace.obs-mip.fr/variable-models-grace-lageos/mean-fields/release-04/

Description: The software package “ClassifyStorms” version 1.0.1 performs a classification of geomagnetic storms according to their interplanetary driving mechanisms based exclusively on magnetometer measurements from ground. In this version two such driver classes are considered for storms dating back to 1930. Class 0 contains storms driven by Corotating or Stream Interaction Regions (C/SIRs) and class 1 contains storms driven by Interplanetary Coronal Mass Ejections (ICMEs). The properties and geomagnetic responses of these two solar wind structures are reviewed, e.g., by Kilpua et al. (2017, http://doi.org/10.1007/s11214-017-0411-3). The classification task is executed by a supervised binary logistic regression model in the framework of python's scikit-learn library. The model is validated mathematically and physically by checking the driver occurrence statistics in dependence on the solar cycle phase and storm intensity. A detailed description of the classification model is given in Pick et al. (2019) to which this software is supplementary material. Under “Files” you can download ClassifyStorms-V1.0.1.zip, which contains the jupyter notebook “ClassifyStorms.ipynb” (https://jupyter.org/) and the python modules “Imports.py”, “Modules.py” and “Plots.py”. Check for an up-to-date release of the software on GitLab via https://gitext.gfz-potsdam.de/pick/public/ClassifyStorms (under Project, Releases). The “Readme.md” file provides all information needed to run or modify “ClassifyStorms” from the GitLab source. The software depends on the input data set “Input.nc”, an xarray Dataset (http://xarray.pydata.org/en/stable) saved in NetCDF format (https://www.unidata.ucar.edu/software/netcdf), which you can also download under “Files”. It contains 1. the HMC index: a three-hour running mean with weights [0.25,0.5,0.25] of the original Hourly Magnetospheric Currents index (HMC index, http://doi.org/10.5880/GFZ.2.3.2018.006). 2. the geomagnetic observatory data: vector geomagnetic disturbances from 34 mid-latitude observatories during 1900-2015 in the Cartesian Centered Dipole coordinate system. The original observatory data was downloaded from the WDC for Geomagnetism, Edinburgh (http://www.wdc.bgs.ac.uk/) and processed as described in section 2.1 of Pick et al. (2019). 3. the “reference” geomagnetic storms: universal time hours of 868 geomagnetic storm peaks together with their interplanetary drivers (class labels 0 or 1, see above) as described in section 2.2 of Pick et al., 2019. These events are taken from published lists (Jian et al., 2006a, 2006b, 2011; Shen et al., 2017; Turner et al., 2009), which are gathered in the separate ASCII file “ReferenceEvents.txt” (under “Files”) for a quick overview. 4. additional quantities for plotting: time series of Kp (since 1932) and Dst (since 1957) geomagnetic indices from the WDC for Geomagnetism, Kyoto (http://wdc.kugi.kyoto-u.ac.jp/wdc/Sec3.html) as well as the yearly mean total sunspot number from WDC-SILSO, Royal Observatory of Belgium, Brussels (http://sidc.be/silso/datafiles). The output of ClassifyStorms is "StormsClassified.csv" (under “Files”). This table lists the Date (Year-Month-Day) and Time (Hour:Minutes:Seconds) of 7546 classified geomagnetic storms together with the predicted interplanetary driver class label (0 or 1) and the corresponding probability (between 0 and 1). Version history: 20 Sep 2019: Version 1.0.1: Correction of plotting mistake in Figure m / Figure S4 (see gitlab repository for details)

Description: Surrogate playground is an automated machine learning approach written for rapidly screening a large number of different models to serve as surrogates for a slow running simulator. This code was written for a reactive transport application where a fluid flow model (hydrodynamics) is coupled to a geochemistry simulator (reactions in time and space) to simulate scenarios such as underground storage of CO2 or hydrogen storage for excess energy from wind farms. The challenge for such applications is that the geochemistry simulator is typically slow compared to fluid dynamics and constitutes the main bottleneck for producing highly detailed simulations of such application scenarios. This approach attempts to find machine learning models that can replace the slow running simulator when trained on input-output data from the geochemistry simulator. The code may be of more general interest as this prototype can be used to screen many different machine learning models for any regression problem in general. To illustrate this it also includes a demonstration example using the Boston housing standard data-set.

Description: Vierzig Prozent der gesamten Klimagas-Emissionen aus der deutschen Landwirtschaft gehen von trockengelegten Mooren aus. Die damit verbundenen gesellschaftlichen Kosten sind höher als der private betriebliche Nutzen. Die Wiedervernässung unserer Moorböden würde einen großen Beitrag zum Klima- und Gewässerschutz leisten. Außerdem würden mehr als 50 landwirtschaftlich nutzbare Pflanzenarten auch auf natürlich erhaltenen Moorböden gedeihen.

Description: The open-source programming language R has gained a central place in the hydrological sciences over the last decade, driven by the availability of diverse hydro-meteorological data archives and the development of open-source computational tools. The growth of R's usage in hydrology is reflected in the number of newly published hydrological packages, the strengthening of online user communities, and the popularity of training courses and events. In this paper, we explore the benefits and advantages of R's usage in hydrology, such as the democratization of data science and numerical literacy, the enhancement of reproducible research and open science, the access to statistical tools, the ease of connecting R to and from other languages, and the support provided by a growing community. This paper provides an overview of a typical hydrological workflow based on reproducible principles and packages for retrieval of hydro-meteorological data, spatial analysis, hydrological modelling, statistics, and the design of static and dynamic visualizations and documents. We discuss some of the challenges that arise when using R in hydrology and useful tools to overcome them, including the use of hydrological libraries, documentation, and vignettes (long-form guides that illustrate how to use packages); the role of integrated development environments (IDEs); and the challenges of big data and parallel computing in hydrology. Lastly, this paper provides a roadmap for R's future within hydrology, with R packages as a driver of progress in the hydrological sciences, application programming interfaces (APIs) providing new avenues for data acquisition and provision, enhanced teaching of hydrology in R, and the continued growth of the community via short courses and events.

Description: Die Arktis erwärmt sich schneller als der Rest der Welt. Damit verringert sich der Temperaturunterschied zwischen Äquator, gemäßigten Breiten auf der einen und Arktis auf der anderen Seite. Dieser Unterschied treibt jedoch das starke Westwindband der Nordhalbkugel an und bestimmt dessen Bahnen und Stärke mit. Der sogenannte Polar-Front-Jetstream hat große Bedeutung für unser Wetter in Deutschland.

Description: Oxygen isotope ratios were measured in zircon by laser fluorination and by SIMS from in over 50 silicic (dacite–rhyolite) volcanic rocks of Triassic to Cretaceous (230-98 Ma) age from the Sierra Nevada batholith, White-Inyo Mountains, and Mojave Desert. These data give broad geographic and temporal context of volcanism in the Mesozoic California arcs system that was previously unobtainable because of secondary hydrothermal exchange that routinely alters original magmatic δ18O values in these rocks (c.f., Sorensen et al. GSAB 1998). SIMS analysis of δ18O using 10 µm spot size, augmented by U-Pb dating by LA-ICP-MS, further allows appraisal of variability within zircon grains and grain populations as potential evidence of assimilation or magma mixing within caldera systems, including mixing during eruptions. Values of δ18O(zircon) in most rocks studied are 5.0–7.5‰, and overlap with values of δ18O in plutonic rocks (6.80±1.85‰, S.D., Lackey et al. 2005,2006,2008,2012). A subset of Late Jurassic (152-148 Ma) tuffs distributed from the Mojave Desert to Mt. Goddard pendant that contain zircons whose δ18O values commonly are 〈5.0‰; such low values are not found in coeval plutonic rocks or dikes of the ca. 148 Ma Independence Dike Swarm. Among these rocks, δ18O values are as low as 2.6‰ and average 4.4±0.8‰; porphyries associated with caldera complexes in the Mojave Desert are similarly low. The restriction of these lower values to volcanic rocks of Late Jurassic age suggests that caldera systems at this time interacted with low-δ18O surface water (meteoric or marine). Such infiltration into caldera environments has not been recognized before or after. The Late Jurassic corresponds to a pronounced but brief transtension event in the arc, which is hypothesized to have impelled mafic mantle melts high into the crust, and also encouraged low-δ18O surface water exchange with arc wall rocks (especially volcanic crust). These two factors thus created a period of low-δ18O magmatism in the upper arc crust that is strikingly mismatched with the δ18O record in coeval plutons. Moreover, the volcanic δ18O record may provide previously unrecognized information about tectonic stress regimes in arc systems as they respond to plate-tectonic reorganizations.

Description: Die Gletscher in Hindukusch, Himalaya oder Karakorum sind bedeutende Eisspeicher. Sie versorgen einige der wichtigsten Flussregionen der Welt wie den Ganges, Indus, Brahmaputra, Mekong oder auch den Irrawaddy mit Wasser. Neue Forschungsergebnisse zeigen, wie sehr die Gletscher in den asiatischen Hochgebirgen gefährdet sind.

Description: Weltweit stiegen die Temperaturen im Permafrost um durchschnittlich 0,30 °C zwischen 2007 bis 2016, dies vor allem im Norden Russlands. Die Erwärmung des Permafrosts hat drastische Folgen für das globale Klima, aber auch für die Infrastruktur in der Arktis und das Auskommen der vier Millionen dort lebenden Menschen.

Description: Worldwide permafrost temperatures rose on average by 0.30°C over a ten year period from 2007 to 2016 most notably in the Russia North. Permafrost warming has drastic consequences for global climate but also for infrastructure in arctic communities and for the livelihood of the four million people that live there.

Description: This paper describes devices to extract α-cellulose from small whole wood samples developed at the Lamont-Doherty Earth Observatory Tree-Ring Lab and explains the procedures for chemical extractions and for the dual analysis of carbon (δ13C) and oxygen (δ18O) stable isotopes. Here, we provide the necessary steps and guidelines for constructing a cellulose extraction system for small amounts of wood and leaves. The system allows the simultaneous extraction of cellulose from 150 samples by means of in-house filter tubes, where chemicals used for the cellulose extraction are exchanged and eliminated in batches. This new implementation diminishes the processing time, minimizes physical sample manipulation and potential errors, increases sample throughput, and reduces the amount of chemicals and analytic costs. We also describe the dual measurement of δ13C and δ18O ratios in tree-ring cellulose using high-temperature pyrolysis in a High Temperature Conversion Elemental Analyzer (TC/EA) interfaced with a Thermo Delta V plus mass spectrometer.

Description: Ocean tides generate electromagnetic (EM) signals that are emitted into space and can be recorded with low-Earth-orbiting satellites. Observations of oceanic EM signals contain aggregated information about global transports of water, heat, and salinity. We utilize an artificial neural network (ANN) as a non-linear inversion scheme and demonstrate how to infer ocean heat content (OHC) estimates from magnetic signals of the lunar semi-diurnal (M2) tide. The ANN is trained using monthly OHC estimates based on oceanographic in-situ data from 1990–2015 and the corresponding computed tidal magnetic fields at satellite altitude. We show that the ANN can closely recover inter-annual and decadal OHC variations from simulated tidal magnetic signals. Using the trained ANN, we present the first OHC estimates from recently extracted tidal magnetic satellite observations. Such space-borne OHC estimates can complement the already existing in-situ measurements of upper ocean temperature and can also allow insights into abyssal OHC, where in-situ data are still very scarce.

Description: Fire regime shifts are driven by climate and natural vegetation changes, but can be strongly affected by human land management. Yet, it is poorly known how humans have influenced fire regimes prior to active wildfire suppression. Among the last 250 years, the human contribution to the global increase in fire occurrence during the mid-19th century is especially unclear, as data sources are limited. Here, we test the extent to which forest management has driven fire regime shifts in a temperate forest landscape. We combine multiple fire proxies (macroscopic charcoal and fire-related biomarkers) derived from highly resolved lake sediments (i.e., 3–5 years per sample), and apply a new statistical approach to classify source area- and temperature-specific fire regimes (biomass burnt, fire episodes). We compare these records with independent climate and vegetation reconstructions. We find two prominent fire regime shifts during the 19th and 20th centuries, driven by an adaptive socio-ecological cycle in human forest management. Although individual fire episodes were triggered mainly by arson (as described in historical documents) during dry summers, the biomass burnt increased unintentionally during the mid-19th century due to the plantation of flammable, fast-growing pine tree monocultures needed for industrialization. State forest management reacted with active fire management and suppression during the 20th century. However, pine cover has been increasing since the 1990s and climate projections predict increasingly dry conditions, suggesting a renewed need for adaptations to reduce the increasing fire risk.