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  • 1
    facet.materialart.
    Unbekannt
    PANGAEA
    In:  Supplement to: Galerne, Christophe; Hasenclever, Jörg (2019): Distinct degassing pulses during magma invasion in the stratified Karoo Basin – New insights from hydrothermal fluid flow modelling. Geochemistry, Geophysics, Geosystems, https://doi.org/10.1029/2018GC008120
    Publikationsdatum: 2023-01-13
    Beschreibung: The movies show the evolution in time of 2-D numerical model calculations investigating hydrothermal fluid flow around a cooling sills in a sedimentary basin. Each movie shows the evolution of a single variable for a specific model setup. The reported variables are: water fraction in the host rock (fH2O), mass of methane (mCH4), permeability (Perm), porosity (Phi), temperature (T), and TOC content of the host rock (TOC). S0: five reference simulations in simplified setups S1-S3 : The basin has been dissected in three regions with different basin depths. Each of these regions was investigated in a specific 2D modelling section which is refered to as setup S1, S2 and S3, respectively.
    Schlagwort(e): File content; File format; File name; File size; Uniform resource locator/link to file
    Materialart: Dataset
    Format: text/tab-separated-values, 24 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    facet.materialart.
    Unbekannt
    PANGAEA
    In:  Supplement to: Hasenclever, Jörg; Knorr, Gregor; Rüpke, Lars H; Köhler, Peter; Morgan, Jason Phipps; Garofalo, Kristin; Barker, Stephen; Lohmann, Gerrit; Hall, Ian R (2017): Sea level fall during glaciation stabilized atmospheric CO2 by enhanced volcanic degassing. Nature Communications, 8, 15867, https://doi.org/10.1038/ncomms15867
    Publikationsdatum: 2023-01-13
    Beschreibung: Paleo-climate records and geodynamic modelling indicate the existence of complex interactions between glacial sea level changes, volcanic degassing, and atmospheric CO2, which may have modulated the climate system's descent into the last ice age. Between ~85-70 ka, during an interval of decreasing axial tilt, the orbital component in global temperature records gradually declined, while atmospheric CO2, instead of continuing is long-term correlation with Antarctic temperature, remained relatively stable. Based on novel global geodynamic models and the joint interpretation of paleo-proxy data as well as biogeochemical simulations, we show that a sea level fall in this interval caused enhanced pressure-release melting in the uppermost mantle, which may have induced a surge in magma and CO2 fluxes from mid-ocean ridges and oceanic hotspot volcanoes. Our results reveal a hitherto unrecognised negative feedback between glaciation and atmospheric CO2 predominantly controlled by marine volcanism on multi-millennial (suborbital) timescales of ~ 5,000-15,000 years.
    Schlagwort(e): File content; File format; File name; File size; Uniform resource locator/link to file
    Materialart: Dataset
    Format: text/tab-separated-values, 10 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Mycopathologia 65 (1978), S. 169-176 
    ISSN: 1573-0832
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Conclusions Iron has a pivotal role in serum inhibition and filamentation. That there may be an inverse relationship between inhibition and filamentation is suggested by the observations that free serum iron abolishes inhibition and stimulates filamentation. Evidence indicates that filamentation results from the interaction of substrates, growth conditions, and temperature, rather than from a single factor. Filamentation occurs during clumping and appears to be necessary for the manifestation of this later process, but any further relationship is unknown. Opsonins seem to be a part of the complement system or their function at least is dependent upon complement activity. Their interaction with surface antigens form chemotactic stimulants but their contribution to the phagocytic destruction of C. Albicans is unclear. All of these serum-Candida interactions are in vitro observations. Although opsonization and phagocytosis probably play a vital role in the in vivo defenses against invading Candida, the contribution of these other interactions to host resistance remain unknown.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 29 (1896), S. 2861-2877 
    ISSN: 0365-9496
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2016-01-21
    Beschreibung: Hydrothermal convection at mid-ocean ridges links the ocean's long term chemical evolution to solid earth processes, forms hydrothermal ore deposits, and sustains the unique chemosynthetic vent fauna. Yet, the depth-extent of hydrothermal cooling and the inseparably connected question of how the lower crust accretes, remain poorly constrained. Here, based on coupled models of crustal accretion and hydrothermal circulation, we provide new insights into which modes of lower crust formation and hydrothermal cooling are thermally viable and most consistent with observations at fast spreading ridges. We integrate numerical models with observations of melt lens depth, thermal structure, and melt fraction. Models matching all these observations always require a deep crustal-scale hydrothermal flow component and less than 50% of the lower crust crystallizing in-situ.
    Print ISSN: 0094-8276
    Digitale ISSN: 1944-8007
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2019
    Beschreibung: Abstract Magma emplacement in organic‐rich sedimentary basins is a main driver of past environmental crises. Using a 2‐D numerical model, we investigate the process of thermal cracking in contact aureoles of cooling sills and subsequent transport and emission of thermogenic methane by hydrothermal fluids. Our model includes a Mohr‐Coulomb failure criterion to initiate hydrofracturing and a dynamic porosity/permeability. We investigate the Karoo Basin, taking into account host‐rock material properties from borehole data, realistic total organic carbon content, and different sill geometries. Consistent with geological observations, we find that thermal plumes quickly rise at the edges of saucer‐shaped sills, guided along vertically fractured high‐permeability pathways. Contrastingly, less focused and slower plumes rise from the edges and the central part of flat‐lying sills. Using a novel upscaling method based on sill‐to‐sediment ratio, we find that degassing of the Karoo Basin occurred in two distinct phases during magma invasion. Rapid degassing triggered by sills emplaced within the top 1.5 km emitted ~1.6·103 Gt of thermogenic methane, while thermal plumes originating from deeper sills, carrying a 13‐times‐greater mass of methane, may not reach the surface. We suggest that these large quantities of methane could be remobilized by the heat provided by neighboring sills. We conclude that the Karoo large igneous province may have emitted as much as ~22.3·103 Gt of thermogenic methane in the half million years of magmatic activity, with emissions up to 3 Gt/year. This quantity of methane and the emission rates can explain the negative δ13C excursion of the Toarcian environmental crisis.
    Digitale ISSN: 1525-2027
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2016-05-01
    Print ISSN: 0167-8655
    Digitale ISSN: 1872-7344
    Thema: Informatik
    Publiziert von Elsevier
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2015-01-01
    Beschreibung: High-temperature (〉300 °C) off-axis hydrothermal systems found along the slow-spreading Mid-Atlantic Ridge are apparently consistently located at outcropping fault zones. While preferential flow of hot fluids along highly permeable, fractured rocks seems intuitive, such efficient flow inevitably leads to the entrainment of cold ambient seawater. The temperature drop this should cause is difficult to reconcile with the observed high-temperature black smoker activity and formation of associated massive sulfide ore deposits. Here we combine newly acquired seismological data from the high-temperature, off-axis Logatchev 1 hydrothermal field (LHF1) with numerical modeling of hydrothermal flow to solve this apparent contradiction. The data show intense off-axis seismicity with focal mechanisms suggesting a fault zone dipping from LHF1 toward the ridge axis. Our simulations predict high-temperature venting at LHF1 only for a limited range of fault widths and permeability contrasts, expressed as the fault’s relative transmissibility (the product of the two parameters). The relative transmissibility must be sufficient to "capture" a rising hydrothermal plume and redirect it toward LHF1 but low enough to prevent extensive mixing with ambient cold fluids. Furthermore, the temperature drop associated with any high permeability zone in heterogeneous crust may explain why a significant part of hydrothermal discharge along slow-spreading ridges occurs at low temperatures.
    Print ISSN: 0091-7613
    Digitale ISSN: 1943-2682
    Thema: Geologie und Paläontologie
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2017-07-07
    Beschreibung: Previous studies have estimated that mantle serpentinization reactions generate H 2 at a rate of 10 10 -10 12 mol per year along the global mid-ocean ridge (MOR) system. Here we present results of 3-D geodynamic simulations that predict rates of additional mantleserpentinization and H 2 production at oceanic transform faults (OTF). We find that the extent and rate of mantle serpentinization increases with OTF length and is maximum at intermediate slip rates of 5 to 10 cm per year.The additional global OTF-relatedproduction of H 2 is found to be between 6.1 and 10.7 x 10 11 mol per year, which is comparable to the predicted background MOR rateof 4.1 – 15.0 x 10 11 mol H 2 /yr.This points tooceanic transform faults as potential sites of intense fluid-rock interaction, where chemosynthetic life could be sustained by serpentinization reactions.
    Print ISSN: 0094-8276
    Digitale ISSN: 1944-8007
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2017-11-13
    Print ISSN: 0169-3913
    Digitale ISSN: 1573-1634
    Thema: Geologie und Paläontologie , Technik allgemein
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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