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  • 1
  • 2
    Monograph available for loan
    Monograph available for loan
    [Edgecumbe, N.Z.] : A. Muller
    Call number: M 15.89146
    Description / Table of Contents: An account of the results of the 2 March 1987 earthquake in the eastern Bay of Plenty and the aftermath's effects on the people and places on the Rangitaiki Plains
    Type of Medium: Monograph available for loan
    Pages: 223 S., , Ill.
    Language: English
    Branch Library: GFZ Library
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  • 3
    Monograph available for loan
    Monograph available for loan
    Garmisch-Partenkirchen : Institut für atmosphärische Umweltforschung der Fraunhofer- Gesellschaft
    Call number: MOP 44829 / Mitte
    Type of Medium: Monograph available for loan
    Pages: 25 S. , graph. Darst.
    Language: English
    Location: MOP - must be ordered
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  • 4
    Call number: 3/S 07.0034(2016)
    In: Annual report
    Type of Medium: Monograph available for loan
    Pages: 51 Seiten
    ISSN: 1865-6439 , 1865-6447
    Parallel Title: Erscheint auch als Annual report ... / Helmholtz Association of German Research Centres
    Language: English
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  • 5
    Journal available for loan
    Journal available for loan
    München : Altop Verlag ; 2007 -
    Call number: Z 19.92410
    Type of Medium: Journal available for loan
    Pages: 30 cm
    ISSN: 1865-4266
    Former Title: Vorg. Nachhaltiges Wirtschaften in Deutschland
    Language: German
    Note: Ungezählte Beil. ab 2010: Special , Ersch. jährl. 4x
    Branch Library: RIFS Library
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  • 6
    Call number: AWI A3-20-93434
    In: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin, Band XXXII, Heft 1
    Type of Medium: Series available for loan
    Pages: 121 Seiten , Illustrationen
    Series Statement: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin 32,1
    Language: German
    Note: Zugleich: Dissertation, Freie Unversität Berlin, [ca. 1963] , INHALTSVERZEICHNIS PROBLEMSTELLUNG UND ZIELSETZUNG 1. BEMERKUNGEN ZUM BEOBACHTUNGSGELÄNDE UND ZUM BEOBACHTUNGSMATERIAL 1.1 Das Beobachtungsgelände 1.2 Das Beobachtungsmaterial 2. HOMOGENITÄTSBETRACHTUNGEN 2.1 Temperatur 2.2 Niederschlag 2.3 Wind 2.4 Sonnenschein und Bewölkung 3. TEMPERATURVERHÄLTNISSE 3.1 Monats- und Jahreswerte 3.2 Tageswerte 3.3 Pentadenwerte 3.4 Häufigkeitsbetrachtungen 3.5 Interdiurne Veränderlichkeit 3.6 Der tägliche Gang 3.7 Vorkommen bestimmter Schwellenwerte 3.71 Frost- und Eistage 3.72 Sommer- und Tropentage 4. DER WASSERGEHALT DER LUFT 4.1 Monats- und Jahreswerte 4.2 Tageswerte 4.3 Häufigkeitsbetrachtungen 4.4 Interdiurne Veränderlichkeit 4.5 Der tägliche Gang 5. BEWÖLKUNGSVERHÄLTNISSE 5.1 Monats- und Jahreswerte 5.2 Tageswerte 5.3 Häufigkeitsbetrachtungen 5.4 Der tägliche Gang 5.5 Heitere und trübe Tage 5.6 Nebel 6. SONNENSCHEIN 6.1 Monats- und Jahreswerte 6.2 Tageswerte 6.3 Der tägliche Gang 7. NIEDERSCHLAGSVERHÄLTNISSE 7.1 Monats- und Jahreswerte 7.2 Niederschlagsbereitschaft 7.3 Tageswerte 7.4 Der tägliche Gang 7.5 Häufigkeitsbetrachtungen 7.6 Niederschlags- und Trockenperioden 7.7 Niederschlag und Wind· 7.8 Schneeverhältnisse 7.81 Schneefall und Schneedecke 7.82 Schneehöhe 7.9 Gewitter 8. WINDVERHÄLTNISSE 8.1 Windrichtung 8.2 Windgeschwindigkeit 8.21 Der jährliche Gang 8.22 Häufigkeitsbetrachtungen 8.23 Sturmtage und Windstillen 8.24 Der tägliche Gang 9.ZUSAMMENFASSUNG VERZEICHNIS DER TEXTTABELLEN VERZEICHNIS DER ABBILDUNGEN LITERATURVERZEICHNIS TABELLENANHANG
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  • 7
    Call number: AWI A3-20-93434-2
    In: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin, Band XXXII, Heft 2
    Type of Medium: Series available for loan
    Pages: 218 Seiten , Illustrationen
    Series Statement: Meteorologische Abhandlungen / Institut für Meteorologie und Geophysik der Freien Universität Berlin 32,2
    Language: German
    Note: Zugleich: Dissertation, Freie Unversität Berlin, [ca. 1963] , INHALTSVERZEICHNIS PROBLEMSTELLUNG UND ZIELSETZUNG 1. BEMERKUNGEN ZUM BEOBACHTUNGSGELÄNDE UND ZUM BEOBACHTUNGSMATERIAL 1.1 Das Beobachtungsgelände 1.2 Das Beobachtungsmaterial 2. HOMOGENITÄTSBETRACHTUNGEN 2.1 Temperatur 2.2 Niederschlag 2.3 Wind 2.4 Sonnenschein und Bewölkung 3. TEMPERATURVERHÄLTNISSE 3.1 Monats- und Jahreswerte 3.2 Tageswerte 3.3 Pentadenwerte 3.4 Häufigkeitsbetrachtungen 3.5 Interdiurne Veränderlichkeit 3.6 Der tägliche Gang 3.7 Vorkommen bestimmter Schwellenwerte 3.71 Frost- und Eistage 3.72 Sommer- und Tropentage 4. DER WASSERGEHALT DER LUFT 4.1 Monats- und Jahreswerte 4.2 Tageswerte 4.3 Häufigkeitsbetrachtungen 4.4 Interdiurne Veränderlichkeit 4.5 Der tägliche Gang 5. BEWÖLKUNGSVERHÄLTNISSE 5.1 Monats- und Jahreswerte 5.2 Tageswerte 5.3 Häufigkeitsbetrachtungen 5.4 Der tägliche Gang 5.5 Heitere und trübe Tage 5.6 Nebel 6. SONNENSCHEIN 6.1 Monats- und Jahreswerte 6.2 Tageswerte 6.3 Der tägliche Gang 7. NIEDERSCHLAGSVERHÄLTNISSE 7.1 Monats- und Jahreswerte 7.2 Niederschlagsbereitschaft 7.3 Tageswerte 7.4 Der tägliche Gang 7.5 Häufigkeitsbetrachtungen 7.6 Niederschlags- und Trockenperioden 7.7 Niederschlag und Wind· 7.8 Schneeverhältnisse 7.81 Schneefall und Schneedecke 7.82 Schneehöhe 7.9 Gewitter 8. WINDVERHÄLTNISSE 8.1 Windrichtung 8.2 Windgeschwindigkeit 8.21 Der jährliche Gang 8.22 Häufigkeitsbetrachtungen 8.23 Sturmtage und Windstillen 8.24 Der tägliche Gang 9.ZUSAMMENFASSUNG VERZEICHNIS DER TEXTTABELLEN VERZEICHNIS DER ABBILDUNGEN LITERATURVERZEICHNIS TABELLENANHANG
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  • 8
    Call number: Z 06.0500
    Type of Medium: Journal available for loan
    Pages: 30 cm
    ISSN: 1824-7741
    Former Title: Vorgänger Geologisch-paläontologische Mitteilungen, Innsbruck
    Language: German , English
    Note: Ersch. unregelmäßig , Beiträge teilweise in Englisch
    Branch Library: GFZ Library
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  • 9
    Call number: IASS 15.89494
    Type of Medium: Monograph available for loan
    Pages: Losebl.-Ausg.
    Edition: Stand: Oktober 2010
    ISBN: 9783768501828
    Language: German
    Branch Library: RIFS Library
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  • 10
    Call number: S 90.0066(162,1)
    In: Geologisches Jahrbuch / A
    Type of Medium: Series available for loan
    Pages: 261 Seiten , Ill., 1 DVD-ROM (12 cm) und 1 Tafel-Beil. ([2] S.)
    ISBN: 9783510968534
    Series Statement: Geologisches Jahrbuch 162
    Classification:
    Engineering Geophysics
    Language: German
    Location: Lower compact magazine
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  • 11
    Monograph non-lending collection
    Monograph non-lending collection
    Leiden : Nijhoff ; 1.2009 -
    Call number: IASS 17.92082
    Type of Medium: Monograph non-lending collection
    ISSN: 1876-8814
    Language: English
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  • 12
    Call number: PIK N 453-17-91096
    Type of Medium: Monograph available for loan
    Pages: 50 Seiten , Illustrationen, Diagramme
    Language: German
    Location: A 18 - must be ordered
    Branch Library: PIK Library
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  • 13
    Monograph available for loan
    Monograph available for loan
    Stuttgart : Schweizerbart Science Publishers ; Volume 1, number 1 (1978)-
    Call number: M 18.91571
    Type of Medium: Monograph available for loan
    Pages: 134 Seiten
    ISSN: 2363-7196
    Series Statement: Global tectonics and metallogeny : special issue Vol. 10/2-4
    Classification:
    Tectonics
    Parallel Title: Erscheint auch als Global tectonics and metallogeny
    Language: English
    Location: Upper compact magazine
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  • 14
    Call number: (DE-599)GBV03709842X
    Type of Medium: Monograph available for loan
    Language: German
    Location: MOP - must be ordered
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  • 15
    Call number: AWI G6-19-92375
    In: Berichte / Christian-Albrechts-Universität zu Kiel, Institut für Geowissenschaften, Nr. 9
    Type of Medium: Monograph available for loan
    Pages: 278 Seiten , Illustrationen
    ISSN: 0175-9302
    Series Statement: Berichte / Christian-Albrechts-Universität zu Kiel, Institut für Geowissenschaften 9
    Language: German
    Note: Zugleich: Dissertation, Christian-Albrechts-Universität zu Kiel, 1999 , INHALTSVERZEICHNIS 1. Einleitung 1.1 Kenntnisstand und offene Fragen 1.2 Fragestellung und Ziele dieser Arbeit 2. Umweltbedingungen in den Arbeitsgebieten 2.1 Hydrographie, Eisverhältnisse und NAO 2.2 Zur Variation von Wassertiefe und Breite der Dänemarkstraße und zur Vereisung Islands während des letzten Glazials 3. Methoden 3.1 Auswahl der Kernstationen 3.2 Probennahme und Analysen (Übersicht) 3.3 Zur Rekonstruktion von Paläobedingungen im Oberflächenwasser Zur Aussage stabiler Isotopenverhältnisse in planktischen Foraminiferen Zur Messung stabiler Isotopenverhältnisse Zur Massenspektrometrie Zur Rekonstruktion von Oberflächentemperaturen Alkane und Alkohole als Maß für Staubeintrag Eistranspmtiertes Material und vulkanische Aschen 3.4 Zur Rekonstruktion von Paläobedingungen im Zwischen-/ Tiefenwasser Häufigkeit von Cibicides- und anderen benthischen Arten (inkl. Taxonomie) Stabile Isotopenverhältnisse in benthischen Foraminiferen 3.5 AMS 14C-Datierungen Probenreinigung 3. 6 Hauptelementanalysen von vulkanischen Asche-Leithorizonten 3. 7 Geomagnetische Meßgrößen und magnetische Suszeptibiltät 3.8 Techniken zur Spektralanalyse 4. Methodische Ergebnisse 4.1 Zum Einfluß der Probenreinigung auf δ18O-/ δ13C-Werte 4.2 Probleme bei der langfristigen Reproduzierbarkeit von δ18O-Zeitreihen 4.3 Einfluß der Korngröße und Artendefinition planktischer Foraminiferen auf SST-Rekonstruktionen in hohen Breiten 4.4 Vergleich der stabilen Isotopenwerte von Cibicides lobatulus und Cibicidoides wuellerstorfi 5. Stratigraphische Grundlagen und Tiefenprofile der Klimasignale 5.1 Stratigraphische Korrelation zwischen parallel-gekernten GKG- und SL-/KL-Profilen 5.2 Flanktische δ18O-/ δ13C-Kurven, 14C-Alter und biostratigraphische Fixpunkte Westliches Islandbecken Kern PS2644 Kern PS2646 Kern PS2647 Kern 23351 Vøring-Plateau Kern 23071 Kern 23074 5.3 Benthische δ18O-/ δ13C-Werte in Kern PS2644 5.4 Siliziklastische Sedimentkomponenten: Eistransportiertes Material Westliches Islandbecken Kern PS2644 Kern PS2646 Kern PS2647 Vøring-Plateau Kern 23071 Kern 23074 5.5 Vulkanische Glasscherben in Kern PS2644: Wind- und Eiseintrag 5.6 Geochemie und Alter einzelner Tephralagen als Leithorizonte Westliches Islandbecken Kern PS2644 Kern PS2646 Kern PS2647 Vøring-Plateau Kern 23071 Kern 23074 5.7 Magnetische Suszeptibilität in den Kernen PS2644, PS2646 und PS2647 Kern PS2644 Kern PS2646 und PS2647 5.8 Geomagnetische Feldintensität und Richtungsänderungen in Kern PS2644 5.9 Variation von Planktonfauna und -flora Westliches Islandbecken: Kern PS2644 Kern PS2646 und PS2647 Vøring-Plateau: Kern 23071 und 23074 5.10 Benthische Foraminiferen in Kern PS2644 6. Entwicklung von Temperatur und Salzgehalt nördlich der Dänemark-Straße 6.1 Variation der Oberflächentemperatur nach Planktonforaminiferen 6.2 Variation der Oberflächentemperatur nach Uk37 6.3 Variation der Oberflächensalinität 7. Die Feinstratigraphie von Kern PS2644 als Basis für eine Eichung der 14C-Altersskala 22 - 55 ka 7.1 Korrelation zwischen den Klimasignalen in Kern PS2644 und der GISP2-Klimakurve zum Kalibrieren der 14C-Alter und Erstellen eines Altersmodells Tephrachronologische Marker Korrelationsparameter und -regeln Sonderfälle/ Probleme bei der Korrelation 7.2 Alters-stratigraphische Korrelation der Klimakurven von Kern 23071 und 23074 7.3 Variation der Altersanomalien zwischen 20 und 55 14C-ka 7.4 Variabilität des planktischen 14C-Reservoiralters in Schmelzwasserbeeinflußten Seegebieten Variation der planktischen 14C-Alter unmittelbar an der Basis von Heinrich-Ereignis 4 Unterschiede zwischen planktischen und benthischen 14C-Altern in der westlichen Islandsee. Zur Erklärung der inversen Altersdifferenzen 7.5 Differenz zwischen 14C- und Kalenderalter: Zeitliche Variation unter Einfluß des Erdmagnetfeldes - Modell und Befund 7.6 Sedimentationsraten der Kerne 23071, 23074 und PS2644 nach dem GISP2-Altersmodell Vøring-Plateau: Kerne 23071 und 23074 Südwest-Islandsee: Kern PS2644 8. Klimaoszillationen im Europäischen Nordmeer in der Zeit und Frequenzdomäne 8.1 "Der Einzelzyklus" in den Klimakurven von Kern PS2644 8.2 Zur Veränderlichkeit der Warm- und Kaltextreme sowie Zyklenlänge Besonderheiten in der Zyklenlänge Variation der Kalt-(Stadiale) Variation der Interstadiale 8.3 Periodizitäten der Klimasignale im Frequenzband der D.-Oe.-Zyklen. Der D.-Oe.-Zyklus von 1470 J., seine Multiplen und harmonischen Schwingungen Weitere Frequenzen: 1000-1150 Jahre- und 490- 510 Jahre-Zyklizitäten Höhere Frequenzen im Bereich von Jahrhunderten und Dekaden 8.4 Phasenbeziehungen und (örtliche) Steuemngsmechanismen der Dansgaard-Oeschger-Zyklen 9. Schlußfolgerungen Danksagung Literaturverzeichnis Anhang
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  • 16
    Call number: MOP 19538/1d-6d
    Type of Medium: Monograph available for loan
    Pages: 111 S.
    ISSN: 0486-2287
    Language: Russian
    Note: In kyrill. Schr.
    Location: MOP - must be ordered
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  • 17
    Monograph available for loan
    Monograph available for loan
    Madrid : Secc
    Call number: PIK N 456-17-90913
    Type of Medium: Monograph available for loan
    Pages: 536 Seiten
    Series Statement: Ministerio de Transportes Turismo Y Comunicaciones : Publicación Serie A 114
    Parallel Title: 1,1=6; 2,1=13 von Publicaciones / D / Ministerio del Aire, Subsecretaria de Aviación Civil, Servicio Meteorológico Nacional
    Language: Spanish
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  • 18
    Monograph available for loan
    Monograph available for loan
    London : Penguin Books
    Type of Medium: Monograph available for loan
    ISBN: 9780141985206
    Language: English
    Branch Library: RIFS Library
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  • 19
    Monograph available for loan
    Monograph available for loan
    Leningrad : Gidrometeorolog. Izd.
    Call number: MOP 33767
    Type of Medium: Monograph available for loan
    Pages: 663 S.
    Language: Russian
    Note: In kyrill. Schr., russ.
    Location: MOP - must be ordered
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  • 20
    Call number: IASS 22.95033
    Type of Medium: Monograph available for loan
    Pages: 378 S , 225 mm x 135 mm
    ISBN: 3899421876 , 978-3-89942-187-3
    Series Statement: Edition panta rei
    Language: German
    Note: Zugl.: Marburg (Lahn), Univ., Habil.-Schr., 2004 u.d.T.: Gutmann, Mathias: Die Medialität des Erfahrens
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  • 21
    Journal available for loan
    Journal available for loan
    Tübingen : Mohr Siebeck ; 1.1884 - 48.1931; N.F. 1.1932/33 - 10.1943/44(1945),3; 11.1948/49(1949) -
    Call number: ZS 22.95039
    Type of Medium: Journal available for loan
    Pages: Online-Ressource
    ISSN: 1614-0974 , 0015-2218 , 0015-2218
    Language: German , English
    Note: N.F. entfällt ab 57.2000. - Volltext auch als Teil einer Datenbank verfügbar , Ersch. ab 2000 in engl. Sprache mit dt. Hauptsacht.
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  • 22
    Type of Medium: Monograph available for loan
    Pages: Bände (Loseblattsammlung)
    ISBN: 9783963144509 , 3963144505
    Subsequent Title: Fortsetzung von EnEV und Energieausweise ...
    Language: German
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  • 23
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 24
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 317 (1993), S. 474-484 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 25
    Publication Date: 2024-02-07
    Description: Biophotonic nanostructures rarely withstand fossilization processes occurring after burial over geologic time. Even more distinctive is a change introduced to the optical properties during diagenetic processes resulting in a different optical appearance. Here, we report and explain the optical appearance of centric diatom frustules obtained from ash-bearing carbonate-cemented concretions on the Greifswalder Oie island (Pomeranian Bay, Germany, southern Baltic Sea). The ultrastructural and mineralogical analysis of the fossil frustules were carried out using electron microscopy techniques and were correlated to the macroscopic and microscopic optical appearance of the frustules before and after acid etching. The unique optical properties of the fossil diatoms were associated with diagenetic nanocrystalline calcite filling the frustules’ areolae. This fill created the macroscopic pale-yellow colour of many frustules, a microscopic iridescence probably associated with diffraction grating behaviour, and microscopic colour rings. The results highlight the unique permineralization process of diatom frustules and might be an addition to the emerging studies on frustule optics and photonics.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 26
    Publication Date: 2024-02-07
    Description: Scientific drilling expeditions offer a unique op- portunity to characterize microbial communities in the sub- surface that have long been isolated from the surface. With subsurface microbial biomass being low in general, biologi- cal contamination from the drilling fluid, sample processing, or molecular work is a major concern. To address this, char- acterization of the contaminant populations in the drilling fluid and negative extraction controls are essential for assess- ing and evaluating such sequencing data. Here, rock cores down to 2250 m depth, groundwater-bearing fractures, and the drilling fluid were sampled for DNA to characterize the microbial communities using a broad genomic approach. However, even after removing potential contaminant popu- lations present in the drilling fluid, notorious contaminants were abundant and mainly affiliated with the bacterial order Burkholderiales. These contaminant microorganisms likely originated from the reagents used for isolating DNA despite stringent quality standards during the molecular work. The detection of strictly anaerobic sulfate reducers such as Candi- datus Desulforudis audaxviator suggested the presence of au- tochthonous deep biosphere taxa in the sequenced libraries, yet these clades represented only a minor fraction of the se- quence counts (〈 0.1 %), hindering further ecological inter- pretations. The described methods and findings emphasize the importance of sequencing extraction controls and can support experimental design for future microbiological stud- ies in conjunction with continental drilling operations.
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  • 27
    Publication Date: 2024-02-07
    Description: Most of in-situ stress data in the Australian continent comes from wellbore stress analysis in deep hydrocarbon reservoirs, and earthquake focal mechanism solutions near the Australian plate boundaries, where geophysical tools facilitate understanding of the present-day stress patterns. This resulted in a paucity of stress information in many other regions such as the northern Bowen Basin, which is an active mining province, but with low seismicity rates and limited deep petroleum exploration. The mining industry runs several hundred kilometres of image logs annually to characterise geotechnical attributes. These logs provide an image from the borehole wall, which facilitates analysis of stress-related borehole deformations for in-situ stress characterisation. This paper examines the orientation of horizontal in-situ stress using different types of image logs in mine boreholes across the northern Bowen Basin. Analyses of 128 km of image logs in 680 vertical boreholes resulted in the interpretation of 9046 pairs of stress-related indicators including 735 drilling induced fractures and 8311 borehole breakouts. Our comprehensive database comprises 890 quality-ranked data records for the orientation of maximum horizontal stress (SHmax), which makes the Bowen Basin as a basin with the highest data density in the world in terms of quality-ranked stress information according to the World Stress Map. Statistical analysis of SHmax orientation reveals that the mean SHmax orientation in northern Bowen Basin is N018◦ ± 16◦. The results show that this orientation is consistent over long distances, which is in contrast with several eastern Australian basins. This uniform stress pattern agrees well with plate-scale geomechanical model predictions, which further highlights the impact of plate boundary forces in the contemporary stress pattern of this region. Detailed image log investigation did not show any systematic rotation of stress; however, some small-scale stress perturbations were observed in the vicinity of sharp stiffness contrasts and geological structures.
    Language: English
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  • 28
    Publication Date: 2024-02-07
    Description: The microbiota is attributed to be important for initial soil formation under extreme climate conditions, but experimental evidence for its relevance is scarce. To fill this gap, we investigated the impact of in situ microbial communities and their interrelationship with biocrust and plants compared to abiotic controls on soil formation in initial arid and semiarid soils. Additionally, we assessed the response of bacterial communities to climate change. Topsoil and subsoil samples from arid and semiarid sites in the Chilean Coastal Cordillera were incubated for 16 weeks under diurnal temperature and moisture variations to simulate humid climate conditions as part of a climate change scenario. Our findings indicate that microorganism-plant interaction intensified aggregate formation and stabilized soil structure, facilitating initial soil formation. Interestingly, microorganisms alone or in conjunction with biocrust showed no discernible patterns compared to abiotic controls, potentially due to watermasking effects. Arid soils displayed reduced bacterial diversity and developed a new community structure dominated by Proteobacteria, Actinobacteriota, and Planctomycetota, while semiarid soils maintained a consistently dominant community of Acidobacteriota and Proteobacteria. This highlighted a sensitive and specialized bacterial community in arid soils, while semiarid soils exhibited a more complex and stable community. We conclude that microorganism-plant interaction has measurable impacts on initial soil formation in arid and semiarid regions on short time scales under climate change. Additionally, we propose that soil and climate legacies are decisive for the present soil microbial community structure and interactions, future soil development, and microbial responses.
    Language: English
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  • 29
    Publication Date: 2024-02-08
    Description: Inland water bodies play a vital role at all scales in the terrestrial water balance and Earth’s climate variability. Thus, an inventory of inland waters is crucially important for hydrologic and ecological studies and management. Therefore, the main aim of this study was to develop a deep learning-based method for inventorying and mapping inland water bodies using the RGB band of high-resolution satellite imagery automatically and accurately. The Sentinel-2 Harmonized dataset, together with ZABAGED-validated ground truth, was used as the main dataset for the model training step. Three different deep learning algorithms based on U-Net architecture were employed to segment inland waters, including a simple U-Net, Residual Attention U-Net, and VGG16-U-Net. All three algorithms were trained using a combination of Sentinel-2 visible bands (Red [B04; 665nm], Green [B03; 560nm], and Blue [B02; 490 nm]) at a 10-meter spatial resolution. The Residual Attention U-Net achieved the highest computational cost due to the increased number of trainable parameters. The VGG16-U-Net had the shortest run time and the lowest number of trainable parameters, attributed to its architecture compared to the simple and Residual Attention U-Net architectures, respectively. As a result, the VGG16-U-Net provided the best segmentation results with a mean-IoU score of 0.9850, a slight improvement compared to other proposed U-Net-based architectures. Although the accuracy of the model based on VGG16-U-Net does not make a difference from Residual Attention U-Net, the computation costs for training VGG16-U-Net were dramatically lower than Residual Attention U-Net.
    Language: English
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  • 30
    Publication Date: 2024-02-08
    Description: Adequate tools for evaluating the Sustainable Intensification of Agriculture (SIA) level are crucial, especially in drylands with limited resources. Based on emergy indices and environmental footprints, We propose an evaluation framework for the case of major crop intensification in Xinjiang, China, and examine the local SIA from 2001 to 2020. The results show that increases in emergy input (EI) of the crop system were achieved with simultaneous increases in water consumption and carbon emissions. The most EI to the system is from economically non-free non-renewable resources (75.1 %), and only 5.4 % from environmentally free renewable resources. The emergy output (EO) of cotton was less than 80 % of wheat and maize, but the carbon footprint (CF) and water footprint (WF) of cotton were much higher than wheat and maize (〉1.18 times and 〉 5.01 times, respectively). We group historical results covering emergy indices, CF, WF, and other production indicators into five dimensions and comprehensively evaluate the level of SIA in Xinjiang according to the changes in the five dimensions. It was found that raising the SIA depended on improving management, productivity, and environmental impact dimension from 2000 to 2005. After 2005, the SIA’s down-turning was due to the trade-offs between management, environmental dimensions, and their indicators and the continuous reduction of sustainability of other dimensions. In addition, the progress and realization of SDG 2, SDG 6, SDG 7, SDG 8, SDG 11, and SDG 12 can effectively improve the SIA. Our study serves as a helpful example for evaluating the level of sustainability of intensive agricultural policies not just in Xinjiang but also in other drylands of the world.
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  • 31
    Publication Date: 2024-02-08
    Description: Rewetting drained peatlands is recognized as a leading and effective natural solution to curb greenhouse gas emissions. However, rewetting creates novel ecosystems whose emission behaviors are not adequately captured by currently used emission factors. These emission factors are applied immediately after rewetting, thus do not reflect the temporal dynamics of greenhouse gas emissions during the period wherein there is a transition to a rewetted steady-state. Here, we provide long-term data showing a mismatch between actual emissions and default emission factors and revealing the temporal patterns of annual carbon dioxide and methane fluxes in a rewetted peatland site in northeastern Germany. We show that site-level annual emissions of carbon dioxide and methane approach the IPCC default emission factors and those suggested for the German national inventory report only between 13 to 16 years after rewetting. Over the entire study period, we observed a source-to-sink transition of annual carbon dioxide fluxes with a decreasing trend of −0.36 t CO2-C ha−1 yr−1 and a decrease in annual methane emissions of −23.6 kg CH4 ha−1 yr−1. Our results indicate that emission factors should represent the temporally dynamic nature of peatlands post-rewetting and consider the effect of site characteristics to better estimate associated annual emissions.
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  • 32
    Publication Date: 2024-02-08
    Description: We present the first sequential structural restoration with flexural backstripping of the Gulf of Mexico US-Mexico conjugate margin salt basin. We construct four large-scale (100s of km) balanced, sequential structural restorations to investigate spatio-temporal patterns of subsidence, geometry of the original salt basin, feedbacks between post-salt structural and stratigraphic evolution, paleo-bathymetry, and crustal configurations. The restorations are based on interpretations of 2D and 3D seismic data, and include sequential sedimentary decompaction, flexural isostatic backstripping, and thermal isostatic corrections. The spatially variable crustal thinning factor is directly measured from seismic data, and lithologic parameters are determined by well penetrations. We present a model for the original salt basin and discuss evidence for and implications of a deep water salt basin setting for the GoM. Our analysis suggests a salt basin that contained ∼1–2 km thick salt in a basin 175–390 km across with ∼1 km of bathymetry after salt deposition. The base of salt is mostly smooth with 〈1 km of local relief in the form of normal faults that disrupt a pre-salt sedimentary section. We find that supra-salt extension and shortening are not balanced, with measurable extension exceeding shortening by 18–30 km on each cross-section. Our subsidence analysis reveals anomalous subsidence totaling 1–2 km during Late Jurassic and Early Cretaceous times that may reflect dynamic topography or depth-dependent thinning. We offer an interpretation of crustal breakup invoking pre-salt clastic sedimentation, salt deposition in a deep water syn-thinning basin, and post-salt lower-crustal exhumation.
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  • 33
    Publication Date: 2024-01-19
    Description: The vapor pressure deficit reflects the difference between how much moisture the atmosphere could and actually does hold, a factor that fundamentally affects evapotranspiration, ecosystem functioning, and vegetation carbon uptake. Its spatial variability and long-term trends under natural versus human-influenced climate are poorly known despite being essential for predicting future effects on natural ecosystems and human societies such as crop yield, wildfires, and health. Here we combine regionally distinct reconstructions of pre-industrial summer vapor pressure deficit variability from Europe’s largest oxygen-isotope network of tree-ring cellulose with observational records and Earth system model simulations with and without human forcing included. We demonstrate that an intensification of atmospheric drying during the recent decades across different European target regions is unprecedented in a pre-industrial context and that it is attributed to human influence with more than 98% probability. The magnitude of this trend is largest in Western and Central Europe, the Alps and Pyrenees region, and the smallest in southern Fennoscandia. In view of the extreme drought and compound events of the recent years, further atmospheric drying poses an enhanced risk to vegetation, specifically in the densely populated areas of the European temperate lowlands.
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  • 34
    Publication Date: 2024-01-19
    Description: The accurate estimation of flood probability is crucial for designing water storage and flood retention structures. However, the assumption of identical distribution in flood samples is unrealistic, given the influence of various flood mechanisms. To address this challenge, we proposed a novel framework based on flood clustering and data pooling that encompasses the key steps such as 1) flood event separation based on a peak-detection flood separation algorithm, 2) grouping flood events using the k-prototypes algorithm, 3) application of the UNprecedented Simulated Extreme ENsemble (UNSEEN) approach to pool reforecast ensemble datasets, and 4) statistical mixing approach to derive common quantiles from all the flood groups. We applied the framework to the Dresden gauge in the Elbe River for a detailed case study. Various tests have been performed to assess the applicability of the UNSEEN approach and the reforecast dataset consistently shows the potential for data pooling. The proposed methodology outperformed the classical approach in terms of goodness-of-fit. The relative difference between the classical and the proposed approach ((classical-proposed)/proposed) for the 100-year return level is 0.16, with a reduction in root mean square error (RMSE) value from 163 to 98 m3/s. Further, replication of the approach to the gauges in North Germany exhibited a relative difference ranging from −0.3 to +0.15 and produced better estimates in terms of RMSE compared with the traditional model. In summary, the proposed framework offers a better estimation of flood probability by addressing the inherent sample inhomogeneity along with the inclusion of unprecedented flood samples.
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  • 35
    Publication Date: 2024-01-19
    Description: African forest are increasingly in decline as a result of land-use conversion due to human activities. However, a consistent and detailed characterization and mapping of land-use change that results in forest loss is not available at the spatial-temporal resolution and thematic levels suitable for decisionmaking at the local and regional scales; so far they have only been provided on coarser scales and restricted to humid forests. Here we present the first high-resolution (5 m) and continental-scale mapping of land use following deforestation in Africa, which covers an estimated 13.85% of the global forest area, including humid and dry forests. We use reference data for 15 different land-use types from 30 countries and implement an active learning framework to train a deep learning model for predicting land-use following deforestation with an F1-score of 84 ± 0.7 for the whole of Africa. Our results show that the causes of forest loss vary by region. In general, small-scale cropland is the dominant driver of forest loss in Africa, with hotspots in Madagascar and DRC. In addition, commodity crops such as cacao, oil palm, and rubber are the dominant drivers of forest loss in the humid forests of western and central Africa, forming an “arc of commodity crops” in that region. At the same time, the hotspots for cashew are found to increasingly dominate in the dry forests of both western and southeastern Africa, while larger hotspots for large-scale croplands were found in Nigeria and Zambia. The increased expansion of cacao, cashew, oil palm, rubber, and large-scale croplands observed in humid and dry forests of western and south-eastern Africa suggests they are vulnerable to future land-use changes by commodity crops, thus creating challenges for achieving the zero deforestation supply chains, support REDD+ initiatives, and towards sustainable development goals.
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  • 36
    Publication Date: 2024-01-19
    Description: Detecting phase arrivals and pinpointing the arrival times of seismic phases in seismograms is crucial for many seismological analysis workflows. For land station data, machine learning methods have already found widespread adoption. However, deep learning approaches are not yet commonly applied to ocean bottom data due to a lack of appropriate training data and models. Here, we compiled an extensive and labeled ocean bottom seismometer (OBS) data set from 15 deployments in different tectonic settings, comprising ∼90,000 P and ∼63,000 S manual picks from 13,190 events and 355 stations. We propose PickBlue, an adaptation of the two popular deep learning networks EQTransformer and PhaseNet. PickBlue joint processes three seismometer recordings in conjunction with a hydrophone component and is trained with the waveforms in the new database. The performance is enhanced by employing transfer learning, where initial weights are derived from models trained with land earthquake data. PickBlue significantly outperforms neural networks trained with land stations and models trained without hydrophone data. The model achieves a mean absolute deviation of 0.05 s for P-waves and 0.12 s for S-waves, and we apply the picker on the Hikurangi Ocean Bottom Tremor and Slow Slip OBS deployment offshore New Zealand. We integrate our data set and trained models into SeisBench to enable an easy and direct application in future deployments.
    Language: English
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  • 37
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    In:  Proceedings of the National Academy of Sciences of the United States of America (PNAS)
    Publication Date: 2024-01-19
    Description: Surface roughness ubiquitously prevails in natural faults across various length scales. Despite extensive studies highlighting the important role of fault geometry in the dynamics of tectonic earthquakes, whether and how fault roughness affects fluid-induced seismicity remains elusive. Here, we investigate the effects of fault geometry and stress heterogeneity on fluid-induced fault slip and associated seismicity characteristics using laboratory experiments and numerical modeling. We perform fluid injection experiments on quartz-rich sandstone samples containing either a smooth or a rough fault. We find that geometrical roughness slows down injection-induced fault slip and reduces macroscopic slip velocities and fault slip-weakening rates. Stress heterogeneity and roughness control hypocenter distribution, frequency–magnitude characteristics, and source mechanisms of injection-induced acoustic emissions (AEs) (analogous to natural seismicity). In contrast to smooth faults where injection-induced AEs are uniformly distributed, slip on rough faults produces spatially localized AEs with pronounced non-double-couple source mechanisms. We demonstrate that these clustered AEs occur around highly stressed asperities where induced local slip rates are higher, accompanied by lower Gutenberg–Richter b-values. Our findings suggest that real-time monitoring of induced microseismicity during fluid injection may allow identifying progressive localization of seismic activity and improve forecasting of runaway events.
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  • 38
    Publication Date: 2024-02-06
    Description: Grain boundary networks of quartz, plagioclase and olivine crystal aggregates in metamorphic rocks have been investigated from the nanometer to the millimeter scale by polarized-light microscopy, SEM, and TEM. The studied materials show different grain sizes and experienced different retrograde P-T histories. The aggregates of quartz and plagioclase are traversed by networks of ∼90% continuously open boundaries with μm-sized cavities along the boundaries or at triple junctions. The boundaries are up to ∼500 nm wide open with typically parallel opposing grain faces. Olivine boundaries are filled with serpentine that does not replace olivine but fills the initially open space homogeneously and mostly with random orientation. For quartz there is no correlation between the crystallographic orientation of grain boundaries and their widths. Amongst all samples analyzed, a weak positive correlation exists between grain size and width of open grain boundaries. The application of measured volume changes and elasticity data from the literature to the cooling-decompression paths of the analyzed materials suggests that fracturing with subsequent widening of the grain boundaries starts at temperatures recognizably below the transition from crystal-plastic to brittle behavior of quartz, plagioclase and olivine but not only under surface conditions. The high amount of open boundaries causes an extensive permeability.
    Language: English
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  • 39
    Publication Date: 2024-02-06
    Description: In the Rafsanjan plain, Iran, the excessive use of groundwater for pistachio irrigation since the 1960s has led to a severe water level decline as well as land subsidence. In this study, the advantages of InSAR analyses and groundwater fow modeling are combined to improve the understanding of the subsurface processes causing groundwater-related land subsidence in several areas of the region. For this purpose, a calibration scheme for the numerical groundwater model was developed, which simultaneously accounts for hydraulic aquifer parameters and sediment mechanical properties of land subsidence and thus considers the impact of water release from aquifer compaction. Simulation results of past subsidence are calibrated with satellite-based InSAR data and further compared with leveling measurements. Modeling results show that land subsidence in this area occurs predominantly in areas with fne-grained sediments and is therefore only partly dependent on groundwater level decline. During the modeling period from 1960 to 2020, subsidence rates of up to 21 cm year−1 are simulated. Due to the almost solely inelastic compaction of the aquifer, this has already led to an irreversible aquifer storage capacity loss of 8.8 km3 . Simulation results of future development scenarios indicate that although further land subsidence cannot be avoided, subsidence rates and the associated aquifer storage capacity loss can be reduced by up to 50 and 36%, respectively, by 2050 through the implementation of improved irrigation management for the pistachio orchards.
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  • 40
    Publication Date: 2024-02-06
    Description: Steranes and hopanes are the biomarkers of eukaryotic sterols and bacterial hopanols. Extracted from sedimentary rock, they are widely used to assess burial temperatures and palaeoecological conditions. The relative proportion of steranes and hopanes is commonly applied as a measure of the flux of eukaryotic versus bacterial biomass into sediments, and the relative abundances of C27, C28 and C29 steranes are proxies for shifts in eukaryote ecology. In Recent sediments, intact sterols provide additional information about particular eukaryotic origins. However, biological lipid distributions are not always recorded faithfully in sediments. Based on observations on modern algae and plants, and on 558 million year old fossil macroalgae from the Ediacaran of the White Sea, we suggest that these biomarker proxies can be severely altered by aerobic microbial reworking, to the extent that a complete loss of primary ecological information may occur. Network analysis on the biomarker data suggests that oxic degradation also affects isomer and homolog distributions of saturated and aromatic steroids, hopanes, cheilanthanes and n-alkanes, generating anomalies in apparent thermal maturity indicators and other proxies. In our dataset, between Ediacaran macroalgae that experienced the least and the most oxic degradation, the absolute concentration of biomarkers decreases 80-fold, and at the same time the proportion of steranes over hopanes decreases by a factor of 82, while the proportion of C29 steranes among total steranes decreases from 91% to 47%. Such redox dependent offsets may explain the recurrently erratic behaviour of numerous biomarker parameters. While these results impart constraints on the interpretation of biomarker distributions, they do provide a tool for evaluating the effects of oxygen exposure and microbial degradation on organic matter preservation in recent and ancient environments and may point towards a solution for the correction of such effects.
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  • 41
    Publication Date: 2024-02-06
    Description: As critical transition zones between the land and the sea, estuaries are not only hotspots of hydrogeochemical and microbial processes/reactions, but also play a vital role in processing and transferring terrestrial fluxes of metals and nutrients to the sea. This study focused on three estuaries in the Gulf of Bothnia. All of them experience frequent inputs of acidic and Mn/metal-rich creek waters due to flushing of acid sulfate soils that are widespread in the creekś catchments. Analyzing existing long-term water chemistry data revealed a strong seasonal variation of Mn loads, with the highest values in spring (after snow melt) and autumn (after heavy rains). We sampled surface waters, suspended particulate matter (SPM), and sediments from the estuarine mixing zones and determined the loads and solid-phase speciation of Mn as well as the composition and metabolic potentials of microbial communities. The results showed that the removal, cycling, and lateral transport of Mn were governed by similar phases and processes in the three estuaries. Manganese X-ray absorption spectroscopy data of the SPM suggested that the removal of Mn was regulated by silicates (e.g., biotite), organically complexed Mn(II), and MnOx (dominated by groutite and phyllomanganates). While the fractional amounts of silicate-bound Mn(II) were overall low and constant throughout the estuaries, MnOx was strongly correlated with the Mn loadings of the SPM and thus the main vector for the removal of Mn in the central and outer parts of the estuaries, along with organically complexed Mn(II). Down estuary, both the fractional amounts and average Mn oxidation state of the MnOx phases increased with (i) the total Mn loads on the SPM samples and (ii) the relative abundances of several potential Mn-oxidizing bacteria (Flavobacterium, Caulobacter, Mycobacterium, and Pedobacter) in the surface waters. These features collectively suggested that the oxidation of Mn, probably mediated by the potential Mn-oxidizing microorganisms, became more extensive and complete towards the central and outer parts of the estuaries. At two sites in the central parts of one estuary, abundant phyllomanganates occurred in the surface sediments, but were converted to surface-sorbed Mn(II) phases at deeper layers (〉3–4 cm). The occurrence of phyllomanganates may have suppressed the reduction of sulfate in the surface sediments, pushing down the methane sulfate transition zone that is typically shallow in estuarine sediments. At the outermost site in the estuary, deposited MnOx were reduced immediately at the water–sediment interface and converted most likely to Mn carbonate. The mobile Mn species produced by the Mn reduction processes (e.g., aqueous Mn(II) and ligand complexed Mn(III)) could partly diffuse into the overlying waters and, together with the estuarine Mn loads carried by the surface waters, transfer large amounts of reactive Mn into open coastal areas and subsequently contribute to Mn shuttling and inter-linked biogeochemical processes over the seafloor. Given the widespread occurrence of acid sulfate soils and other sulfidic geological materials on many coastal plains worldwide, the identified Mn attenuation and transport mechanisms are relevant for many estuaries globally.
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  • 42
    Publication Date: 2024-02-06
    Description: The Cretaceous provides us with an excellent case history of ocean-climate-biota system perturbations. Such perturbations occurred several times during the Cretaceous, such as oceanic anoxic events and the end-Cretaceous mass extinction, which have been the subject of an abundant literature. Other perturbations, such as the mid-Maastrichtian Event (MME) remain poorly understood. The MME was associated with global sea-level rise, changes in climate and deep-water circulation that were accompanied by biotic extinctions including ‘true inoceramids’ and the demise of the Caribbean-Tethyan rudist reef ecosystems. So far, the context and causes behind the MME remain poorly studied. We conducted high-resolution integrated biotic, petrological and geochemical studies in order to fill this knowledge gap. We studied, in particular, carbonate Nd and Os isotopes, whole-rock Hg, C and N content, C and N isotopes in organic matter, S isotopes in carbonate-associated sulfate, along with C and O isotopes in foraminifera from the European Chalk Sea: the Polanówka UW-1 core from Poland and the Stevns-1 core from Denmark. Our data showed that sea-level rise of ∼50–100 m lasted around ∼2 Ma and co-occurred with anomalously high mercury concentration in seawater. Along with previously published data, our results strongly suggest that the MME was driven by intense volcanic–tectonic activity, likely related to the production of vast oceanic plateaus (LIP, Large Igneous Province). The collapse of reef ecosystems could have been the consequence of LIP-related environmental stress factors, including climate warming, presumably caused by emission of greenhouse gases, modification of the oceanic circulation, oceanic acidification and/or toxic metal input. The disappearance of the foraminifer Stensioeina lineage on the European shelf was likely caused by the collapse of primary production triggered by sea-level rise and limited amount of nutrient input. Nd isotopes and foraminiferal assemblages attest for changes in sea-water circulation in the European Shelf and the increasing contribution of North Atlantic water masses
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  • 43
    Publication Date: 2024-02-01
    Description: The structural response to compression of the synthetic high-pressure hydroxide perovskite MgSi(OH)6, the so-called “3.65 Å phase,” has been determined to 8.4 GPa at room temperature using single-crystal XRD in the diamond-anvil cell. Two very similar structures have been determined in space groups P21 and P21/n, for which differences in oxygen donor-acceptor distances indicate that the non-centrosymmetric structure is likely the correct one. This structure has six nonequivalent H sites, of which two are fully occupied and four are half-occupied. Half-occupied sites are associated with a well-defined crankshaft of hydrogen-bonded donor-acceptor oxygens extending parallel to c. Half occupancy of these sites arises from the averaging of two orientations of the crankshaft H atoms (|| ±c) in equal proportions. The P21 and P21/n structures are compared. It is shown that the former is likely the correct space group, which is also consistent with recent spectroscopic studies that recognize six nonequivalent O-H. The structure of MgSi(OH)6 at pressures up to 8.4 GPa was refined in both space groups to see how divergent the two models are. There is a very close correspondence between the responses of the two structures implying that, at least to 8.4 GPa, non-centrosymmetry does not affect compressional behavior. The very different compressional behavior of MgO6 and SiO6 octahedra observed in this study suggests that structural phase transformations or discontinuities likely occur in MgSi(OH)6 above 9 GPa.
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  • 44
    Publication Date: 2024-02-01
    Description: Earth’s magnetic field is a dynamic, changing phenomenon. The geomagnetic field consists of contributions from several sources, of which the main field originating in Earth’s core makes up the bulk. On regional and local scales at Earth’s surface, the lithospheric field can make a substantial contribution to the overall field and therefore needs to be considered in field models. A locally derived regional core field model, named HMOREG, has been shown to give accurate predictions of the southern African region. In this study, a new regional field model called the South African Regional Core and Crust model (SARCC) is introduced. This is the first time that a local lithospheric model, estimated by employing the revised spherical cap harmonic analysis modelling method, has been combined with the core component of CHAOS-6, a global field model. It is compared here with the existing regional field model as well as with global core field models. The SARCC model shows small-scale variations that are not present in the other three models. Including a lithospheric magnetic field component likely contributed to the better performance of the SARCC model when compared to other global and local field models. The SARCC model showed a 33% reduction in error compared to surface observations obtained from field surveys and INTERMAGNET stations in the Y component, and HMOREG showed a 7% reduction in error compared to the global field models. The new model can easily be updated with global geomagnetic models that incorporate the most recent, state-of-the-art core and magnetospheric field models.
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  • 45
    Publication Date: 2024-02-01
    Description: The Combination Service for Time-variable Gravity fields (COST-G) operationally provides combinations of monthly Earth gravity field models derived from observations of the microwave ranging instrument of the GRACE Follow-on (GRACE-FO) satellite mission, applying the quality control and combination methodology originally developed by the Horizon 2020 project European Gravity Service for Improved Emergency Management for the data of the GRACE satellites. In the frame of the follow-up Horizon 2020 project Global Gravity-based Groundwater Product (G3P), the GRACE-FO combination is used to derive global grids of groundwater storage anomalies. To meet the user requirements and achieve optimal signal-to-noise ratio, the combination has been further developed and extended to incorporate: • new time-series based on the alternative accelerometer transplant product generated in the frame of the project by the Institute of Geodesy at the Graz University of Technology, which specifically improves the estimation of the C30 coefficient and also reduces the noise at medium to short wavelengths, and • the new time-series AIUB–GRACE-FO–RL02 of monthly GRACE-FO gravity fields, which is derived at the Astronomical Institute of the University of Bern by applying empirical noise modelling techniques. The COST-G quality control confirms the consistency of the contributing GRACE-FO time-series concerning the signal amplitude of seasonal hydrology in large river basins and the secular mass change in polar regions, but it also indicates rather diverse noise characteristics. The difference in the noise levels is taken into account in the combination process by relative weights derived by variance component estimation on the solution level. The weights are expected to be inverse proportional to the noise levels of the individual gravity field solutions. However, this expectation is violated when applying the weighting scheme as developed for the GRACE combination. The reason is found in the high-order coefficients of the gravity field, which are poorly determined from the low–low range-rate observations due to the observation geometry and suffer from aliasing due to the malfunctioning accelerometer onboard one of the GRACE-FO satellites. Hence, for the final G3P-combination a revised weighting scheme is applied where the gravity field coefficients beyond order 60 are excluded from the determination of the weights. The quality of the combined gravity fields is assessed by comparison of the noise content and the signal-to-noise ratio with the individual time-series. Independent validation is provided by the COST-G validation centre at the GFZ German Research Centre for Geosciences, where orbit fits of the low-flying Gravity and steady-state Ocean Circulation Explorer satellite are performed that confirm the high quality of the combined GRACE-FO gravity fields. By the end of the G3P project, the new combination scheme is implemented by COST-G as the new COST-G–GRACE-FO–RL02 and continued to be used for the operational GRACE-FO combination.
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  • 46
    Publication Date: 2023-10-20
    Description: Application of Aquifer Thermal Energy Storage with High Temperatures (HT-ATES) ranging from 60–90 is a promising technique to store large amounts of energy in urban areas. However, these areas typically lack information on hydrogeological and thermal parameters of the subsurface to determine the potential for energy storage. Moreover, conventional exploration methods as pumping tests do not account for the variation in density caused by the high temperature gradients or changes in salinity as encountered in HT-ATES operation. The objective of this study is therefore to develop best practices for characterizing the hydrogeological and thermal properties of groundwater wells and their surrounding formation that determine the potential performance of HT-ATES-systems. In addition to conventional pumping tests, a set of Push–Pull tracer Tests (PPTs) with cold and hot water are proposed and scrutinized using Berlin as case study. There, the research well Gt BChb 1/2015, which is characterized by a reservoir temperature of 17 at a depth between 220 und 230 m below ground surface was tested. In 2017, seven Slug-Withdrawal Tests (SWTs), a Step-Rate-Test (SRT), a production tests, and two Push–Pull tracer Tests (PPTs) with hot and cold water were performed during a period of 40 days. These tests were accompanied by Distributed-Temperature-Sensing (DTS) monitoring. The temperature measurements provide indications of injection areas based on the warmback period during a PPT with 81 hot water. The determined aquifer transmissibility , the related Productivity Index (), and maximum flow rates of about indicate that the aquifer has potential for HT-ATES. However, the PPT and the DTS monitoring revealed cross flow between the target aquifer and an overlying aquifer. Thus, a new well with a design avoiding cross flow is required to utilize the aquifer’s energy storage potential. A set of best practices for characterizing HT-ATES potential was derived from the experiences in this study.
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  • 47
    Publication Date: 2023-10-11
    Description: At the geothermal research platform Gross Schönebeck (NE German Basin), we analysed 3-D seismic reflection data to determine the degree and direction of azimuthal velocity anisotropy which is interpreted as the effect of sub-vertical fracturing. Above the Zechstein salt, the observed anisotropy roughly correlates to fault structures formed by an upwelling salt pillow. Below the salt, faults are not obvious and the direction of less pronounced anisotropy and interpreted fracturing follows the trend of the regional stress field. The fracturing in an extensional setting above salt pillows may cause higher permeability and better conditions for geothermal exploitation.
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  • 48
    Publication Date: 2024-01-18
    Description: Stratigraphy along the Brazilian Equatorial Margin is a crucial guide to the geodynamic history of rifting of Pangea and formation of the South Atlantic Ocean. Understanding the evolution of the Brazilian Equatorial Margin, which intersects the Saint Paul and Romanche Fracture Zones on the western margin of South Atlantic Ocean, is also key for reconstructing eustatic histories and natural resource exploration. In this study, we quantify the stratigraphic and subsidence histories of three sedimentary basins—Barreirinhas, Ceará, Potiguar—that sit within the margin. Stratigraphy was mapped using ca. 900-line-km of two-dimensional seismic data. Biostratigraphic and check-shot data from 23 wells drilled on the continental shelf, slope and in the distal parts of these basins were used to date and depth-convert stratigraphy. Check-shot data were also used to parameterise compaction. The mapped stratigraphy was backstripped to calculate subsidence histories for the basins. Subsidence curves were decompacted, water-loaded and corrected for palaeo-water depths using biostratigraphic data from well reports. The mapped stratigraphy of the Barreirinhas and Ceará Basins and theoretical subsidence curves indicate that stretching factors did not exceed 1.6. These values suggest that these basins can be regarded as failed rifts. In contrast, more distal stratigraphy mapped in the Potiguar Basin to the south indicates that it stretched by a factor of 5–6. Calculated subsidence histories indicate that this basin formed primarily because of Cretaceous rifting and Cretaceous to Recent post-rift thermal sag, with amplitudes governed by the amount of initial stretching.
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  • 49
    Publication Date: 2024-01-18
    Description: The Jinsha River basin in the upper reaches of the Yangtze River in China is prone to strong geological activities, with numerous large-scale landslides along its banks that can potentially trigger a cascade of flood hazards. Recent seismic events such as the Wenchuan and Luding earthquakes have heightened the likelihood of landslide collapses along the slopes of the Jinsha River, thereby increasing the risk of a large-scale landslide-dam-break-flood hazard chain. Among these landslides, the ancient Woda landslide is currently in a state of slow deformation, and if reactivated, it can potentially obstruct the river and trigger catastrophic outburst floods. This study uses the integrated continuum method to simulate the dynamic processes associated with large-scale slope failures and the formation of landslide dams. Furthermore, the outburst flood resulting from the dam breach is modeled by combining the dammed lake flow model and the shallow water equation, allowing for the simulation of long-distance flood propagation. The findings indicate that the Woda landslide has the potential to create a dam of approximately 68.1 m in height, with a corresponding dammed-lake volume of about 7.10 × 108 m3. The peak flow rate of the resulting outburst flood can reach 4.4 × 104 m3/s, leading to an extensive impact zone reaching 140 km downstream. This flood inundates several downstream villages, towns, and even the Sichuan-Tibet Railway which is under construction. Moreover, the study reveals that the resistance coefficient of landslides significantly influences the entire hazard chain evolution process. Lowering the resistance coefficient of landslides leads to a considerable increase in the height of the landslide dam, amplification of the peak flow rate of the outburst flood, and an elevated risk for downstream elements situated at greater distances.
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  • 50
    Publication Date: 2024-01-18
    Description: Forecasting eruptions is a fundamental goal of volcanology. However, difficulties in identifying eruptive precursors, fragmented approaches and lack of resources make eruption forecasting difficult to achieve. In this Review, we explore the first-order scientific approaches that are essential to progress towards forecasting the time and location of magmatic eruptions. Forecasting in time uses different monitoring techniques, depending on the conduit-opening mode. Ascending magma can create a new conduit (closed-conduit eruptions), use a previously open conduit (open-conduit eruptions) or flow below a solidified magma plug (semi-open-conduit eruptions). Closed-conduit eruptions provide stronger monitoring signals often detected months in advance, but they commonly occur at volcanoes with poorly known pre-eruptive behaviour. Open-conduit eruptions, associated with low-viscosity magmas, provide more subtle signals often detected only minutes in advance, although their higher eruption frequency promotes more testable approaches. Semi-open-conduit eruptions show intermediate behaviours, potentially displaying clear pre-eruptive signals days in advance and often recurring repeatedly. However, any given volcano can experience multiple conduit-opening modes, sometimes simultaneously, requiring combinations of forecasting approaches. Forecasting the location of vent opening relies on determining the stresses controlling magma propagation, deformation and seismic monitoring. The use of physics-based models to assimilate monitoring data and observations will substantially improve forecasting, but requires a deeper understanding of pre-eruptive processes and more extensive monitoring data.
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  • 51
    Publication Date: 2024-01-18
    Description: Beryllium isotopes have emerged as a quantitative tracer of continental weathering, but accurate and precise determination of the cosmogenic 10Be and stable 9Be in seawater is challenging, because seawater contains high concentrations of matrix elements but extremely low concentrations of 9Be and 10Be. In this study, we develop a new, time-efficient procedure for the simultaneous preconcentration of 9Be and 10Be from (coastal) seawater based on the iron co-precipitation method. The concentrations of 9Be, 10Be, and the resulting 10Be/9Be ratio for Changjiang Estuary water derived from the new procedure agree well with those obtained from the conventional procedure requiring separate preconcentration for 9Be and 10Be determinations. By avoiding the separate preconcentration, our newly developed procedure contributes toward more time-efficient handling of samples, less sample cross-contamination, and a more reliable 10Be/9Be ratio. Prior to this, we validated the iron co-precipitation method using artificial seawater and natural water samples from the Amazon Estuary regarding: (1) the “matrix effect” for Be analysis, (2) its extraction efficiency for pg g−1 levels Be in the presence and absence of organic matter, and (3) the data comparability with another preconcentration method. We calculated that for the determination of 9Be and 10Be in most open ocean seawater with typical 10Be concentrations of 〉 500 atoms g−1, good precisions (〈 5%) can be achieved using less than 3 liters of seawater compared to more than 20 liters routinely used previously. Even for coastal seawater with extremely low 10Be concentration (e.g., 100 atoms g−1), we estimate a maximum amount of 10 liters to be adequate.
    Language: English
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  • 52
    Publication Date: 2024-01-18
    Description: Accurate age estimates are crucial for assessing the life-histories of fish and providing management advice, but validation studies are rare for many species. We corroborated age estimates with annual cycles of oxygen isotopes (δ18O) in otoliths of 86 northern pike (Esox lucius) from the southern Baltic Sea, compared results with visual age estimates from scales and otoliths, and assessed bias introduced by different age-estimation structures on von Bertalanffy growth models and age-structured population models. Age estimates from otoliths were accurate, while age estimates from scales significantly underestimated the age of pike older than 6 years compared to the corroborated reference age. Asymptotic length () was larger, and the growth coefficient was lower for scale ages than for corroborated age and otolith age estimates. Consequentially, scale-informed population models overestimated maximum sustainable yield (), biomass at (), relative frequency of trophy fish (), and optimal minimum length limit but underestimated fishing mortality at (). Using scale-based ages to inform management regulations for pike may therefore result in conservative management and lost yield. The overestimated asymptotic length may instill unrealistic expectations of trophy potential in recreational anglers targeting large pike, while the overestimation in MSY would cause unrealistic expectations of yield potential in commercial fishers.
    Language: English
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  • 53
    Publication Date: 2023-12-22
    Description: Monitoring urban heat island (UHI) effect is critical because it causes health problems and excessive energy consumption more energy when cooling buildings. In this study, we propose an approach for UHI monitoring by fusing data from ground-based global navigation satellite system (GNSS), space-based GNSS radio occultation (RO), and radiosonde. The idea of the approach is as follows: First, the first and second grid tops are defined based on historical RO and radiosonde observations. Next, the wet refractivities between the first and second grid tops are fitted to higher-order spherical harmonics and they are used as the inputs of GNSS tomography. Then, the temperature and water vapor partial pressure are estimated by using best search method based on the tomography-derived wet refractivity. In the end, the UHI intensity is evaluated by calculating the temperature difference between the urban regions and nearby rural regions. Feasibility of the UHI intensity monitoring approach was evaluated with GNSS RO and radiosonde data in 2010–2019, as well as ground-based GNSS data in 2020 in Hong Kong, China, by taking synoptic temperature data as reference. The result shows that the proposed approach achieved an accuracy of 1.2 K at a 95% confidence level.
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  • 54
    Publication Date: 2024-01-16
    Description: Arctic warming increases the degradation of permafrost soils but little is known about floodplain soils in the permafrost region. This study quantifies soil organic carbon (SOC) and soil nitrogen stocks, and the potential CH4 and CO2 production from seven cores in the active floodplains in the Lena River Delta, Russia. The soils were sandy but highly heterogeneous, containing deep, organic rich deposits with 〉60% SOC stored below 30 cm. The mean SOC stocks in the top 1 m were 12.9 ± 6.0 kg C m−2. Grain size analysis and radiocarbon ages indicated highly dynamic environments with sediment re-working. Potential CH4 and CO2 production from active floodplains was assessed using a 1-year incubation at 20°C under aerobic and anaerobic conditions. Cumulative aerobic CO2 production mineralized a mean 4.6 ± 2.8% of initial SOC. The mean cumulative aerobic:anaerobic C production ratio was 2.3 ± 0.9. Anaerobic CH4 production comprised 50 ± 9% of anaerobic C mineralization; rates were comparable or exceeded those for permafrost region organic soils. Potential C production from the incubations was correlated with total organic carbon and varied strongly over space (among cores) and depth (active layer vs. permafrost). This study provides valuable information on the carbon cycle dynamics from active floodplains in the Lena River Delta and highlights the key spatial variability, both among sites and with depth, and the need to include these dynamic permafrost environments in future estimates of the permafrost carbon-climate feedback.
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  • 55
    Publication Date: 2024-01-16
    Description: This contribution is presenting a multidisciplinary investigation of heterogeneities in a clay rock formation, based on seismic tomography, logging and core analysis, as a reconnaissance study for a diffusion experiment. Diffusion experiments in clay rock formations provide crucial experimental data on diffusive transport of radionuclides (RN) in extremely low hydraulic conductivity media. Previous diffusion experiments, conducted, for example, in the Mont Terri underground rock laboratory within the relatively homogeneous shaly facies of Opalinus Clay, and modelling studies of these experiments have demonstrated that the clay rock could sufficiently well be described as a homogeneous anisotropic medium. For other lithofacies, characterized by larger heterogeneity, such simplification may be unsuitable, and the description of heterogeneity over a range of scales will be important. The sandy facies of the Opalinus Clay exhibits a significantly more pronounced heterogeneity compared to the shaly facies, and a combined characterization and RN diffusion study has been initiated to investigate various approaches of heterogeneity characterization and subsequent diffusion in a heterogeneous environment. As an initial step, two inclined exploratory boreholes have been drilled to access the margins of the experiment location. These boreholes have been used to acquire a cross-hole tomographic seismic data set. Optical, natural gamma and backscattering logging were applied and rock cores were analysed. The integrated results of these investigations allowed the identification of an anomalous brighter layer within the investigated area of the sandy facies of approximately 1 m thickness and with its upper bound at roughly 10 m depth within the inclined exploratory wells. Mineralogical analyses revealed only slight variations throughout the rock cores and indicated that the anomalous layer exhibited a slightly higher quartz content, and locally significantly higher calcite contents, accompanied by a lower content of clay minerals. The anomalous layer was characterized by reduced natural gamma emissions, due to the lower clay content, and increased neutron backscattering likely indicating an increased porosity. Seismic P-wave velocities, derived from anisotropic tomography, exhibited a maximal gradient near the top of this layer. The transition from the overlaying darker rock matrix into this layer has been identified as an appropriate location for the setup of a tracer diffusion experiment in a heterogeneous environment.
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  • 56
    Publication Date: 2024-01-16
    Description: Accurate assessment of the rate and state friction parameters of rocks is essential for producing realistic earthquake rupture scenarios and, in turn, for seismic hazard analysis. Those parameters can be directly measured on samples, or indirectly based on inversion of coseismic or postseismic slip evolution. However, both direct and indirect approaches require assumptions that might bias the results. Aiming to reduce the potential sources of bias, we take advantage of a downscaled analog model reproducing megathrust earthquakes. We couple the simulated annealing algorithm with quasi-dynamic numerical models to retrieve rate and state parameters reproducing the recurrence time, rupture duration and slip of the analog model, in the ensemble. Then, we focus on how the asperity size and the neighboring segments' properties control the seismic cycle characteristics and the corresponding variability of rate and state parameters. We identify a tradeoff between (a–b) of the asperity and (a–b) of neighboring creeping segments, with multiple parameter combinations that allow mimicking the analog model behavior. Tuning of rate and state parameters is required to fit laboratory experiments with different asperity lengths. Poorly constrained frictional properties of neighboring segments are responsible for uncertainties of (a–b) of the asperity in the order of per mille. Roughly one order of magnitude larger uncertainties derive from asperity size. Those results provide a glimpse of the variability that rate and state friction estimates might have when used as a constraint to model fault slip behavior in nature.
    Language: English
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  • 57
    Publication Date: 2024-01-15
    Description: Situated within a 1.07 million-year-old meteorite crater, Lake Bosumtwi in Ghana stands as a pivotal location for comprehending climatic, ecological and environmental fluctuations within the sub-Saharan region of West Africa. The region's susceptibility to seasonal environmental shifts and climate oscillations is heightened by the annual movements of the tropical rain belt driven by atmospheric circulation. Yet, there is no satisfying age-depth model available for the entire sedimentary sequence strongly limiting our understanding of changes in this circulation pattern and associated (broad-scale) environmental responses during the last million years in the local to regional context of Lake Bosumtwi. To overcome this, we statistically examine the cyclicity in total natural gamma ray (NGR) data on a core from the lake's centre and create a cyclostratigraphic age-depth model. The calculated maximum age of 946 ka agrees well with the meteorite impact age (∼10 % offset). In order to refine this purely statistical approach, we also perform a correlative age-depth model using 33 tie points accounting for the complexity of climatic and environmental imprints to the NGR record that may exceed direct insolation related effects. Special attention is paid to the core's robustly dated (14C, OSL, U/Th) uppermost part covering the last 200 ka. Here, high NGR and co-varying K counts coincide with warm periods (except of the water-saturated and unconsolidated Holocene part) and the inverse for glacials and stadials. Based on this, we define tie points for correlating our NGR data to the age-depth model of a NE Atlantic SST record. Comparing our results to the correlation target, other global climate records and Sahara dust flux data reveals striking similarities and supports a proxy understanding with increased in wash of K-enriched terrigenous material from the crater rims in warm and moist periods (high NGR) and K-depleted dust input in stadials possibly contributing to low NGR values in addition to reduced input of K-enriched sediments from the crater rims. Our correlative age model results in precession amplitudes matching eccentricity well, providing further support especially because an over-tuning is unlikely with the used 33 tie points. Overall we provide crucial chronological context to numerous datasets along with environmental constrains that can be used to study the potential habitat availability of early anatomically modern humans in West Africa.
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  • 58
    Publication Date: 2024-01-15
    Description: The evolution of the local stress field of faults under tectonic stresses is crucial to predict earthquakes. In this study, we investigated the stress sensitivity of an analogue fault model with dimensions of 2 m × 1 m × 1 m, prepared from cement, gypsum, river sand, putty powder, and borax mixture. The angle between the fault strike and the maximum stress direction was varied, and the variation in the stress near the analogue fault (area 1200 × 400 mm; width 5 mm) was determined. The crack growth law of the analogue fault was found to be consistent with a simple Riedel shear model. A main strike-displacement zone was formed, and its direction was parallel to that of the analogue fault. Fault development was described by three stages based on stress–strain relationships: a nucleus stage, a stable growth, and an unstable growth stage. The deflection angle (the deflection angle of the local principal stresses) range of the local stress field was (− 45°, 45°), and it varied most significantly in the nucleus stage. The closer to the fault, the greater the variation range in the deflection angle. The variation range was greater in the fault compression quadrants than in the dilatation quadrants. The correlation between the deflection angle and the relative deformation velocity of the fault was stronger in the stable growth stage than in the other stages. In this stage, the angle–deformation–velocity correlation could be well fitted using a logistic trend model. These findings can be of importance to better understand the nucleation and mechanisms of fault slip-induced earthquakes under varying fault-strike-stress conditions.
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  • 59
    Publication Date: 2024-01-15
    Description: The yield and composition of tar depending on coal rank and pressure during underground coal gasification (UCG) were studied. Two coals were used in a series of ex-situ UCG experiments: a Welsh semi-anthracite (Six Feet) and a Polish bituminous coal (Wesoła). Four high-pressure gasification trials under two distinct pressure regimes (20 and 40 bar) were conducted. The tar samples were collected directly from the reactor outlet. The following groups of compounds were analysed by use of gas chromatography (GC-MS): light monoaromatic hydrocarbons (BTEX – benzene, toluene, ethylbenzene and xylenes), polycyclic aromatic hydrocarbons (PAHs) and phenols. A series of gasification experiments revealed significant differences in tar yields and composition depending on the coal rank and gasification pressure. Significant decreases in tar contents were observed with the increase in gasification pressure from 20 to 40 bar for both coals. The total yields of the analysed tar components per kg of gasified coal were 2.58 g and 0.41 g for the experiments conducted on the Six Feet samples at 20 bar and 40 bar, respectively. The corresponding values for the Wesoła coal amounted to 5.48 g and 0.95 g. In all experiments, BTEX was a dominant group of tar components, constituting 69–86 % of the total tar yield within the tested range of compounds. The present study further proves that gasification pressure has a significant effect on the chemical composition of the produced UCG tars for both coal samples under study.
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  • 60
    Publication Date: 2024-01-15
    Description: Traditionally, the emplacement of the Large Igneous Provinces (LIPs) is considered to have caused continental break-up. However, this does not always seem to be the case, as illustrated by, for example, the Siberian Traps, one of the most voluminous flood basalt events in Earth history, which was not followed by lithospheric rupture. Moreover, the classical model of purely active (plume-induced) rifting and continental break-up often fails to do justice to widely varying tectonic impacts of Phanerozoic LIPs. Here, we show that the role of the LIPs in rupture of the lithosphere ranges from initial dominance (e.g., Deccan LIP) to activation (e.g., Central Atlantic Magmatic Province, CAMP) or alignment (e.g., Afar LIP). A special case is the North Atlantic Igneous Province (NAIP), formed due to the “re-awakening” of the Iceland plume by the lateral propagation of the spreading ridge and the simultaneous approach of the plume conduit to adjacent segments of the thinner overlying lithosphere. The proposed new classification of LIPs may provide useful guidance for future research, particularly with respect to some inherent limitations of the common paradigm of purely passive continental break-up and the assumption of a direct link between internal mantle dynamics and the timing of near-surface magmatism.
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  • 61
    Publication Date: 2024-01-15
    Description: In this article, a high-resolution acoustic emission sensor, accelerometer, and broadband seismometer array data set is made available and described in detail from in situ experiments performed at Äspö Hard Rock Laboratory in May and June 2015. The main goal of the hydraulic stimulation tests in a horizontal borehole at 410m depth in naturally fractured granitic rock mass is to demonstrate the technical feasibility of generating multi-stage heat exchangers in a controlled way superiorly to former massive stimulations applied in enhanced geothermal projects. A set of six, sub-parallel hydraulic fractures is propagated from an injection borehole drilled parallel to minimum horizontal in situ stress and is monitored by an extensive complementary sensor array implemented in three inclined monitoring boreholes and the nearby tunnel system. Three different fluid injection protocols are tested: constant water injection, progressive cyclic injection, and cyclic injection with a hydraulic hammer operating at 5 Hz frequency to stimulate a crystalline rock volume of size 30m30m30m at depth. We collected geological data from core and borehole logs, fracture inspection data from an impression packer, and acoustic emission hypocenter tracking and tilt data, as well as quantified the permeability enhancement process. The data and interpretation provided through this publication are important steps in both upscaling laboratory tests and downscaling field tests in granitic rock in the framework of enhanced geothermal system research. Data described in this paper can be accessed at GFZ Data Services under https://doi.org/10.5880/GFZ.2.6.2023.004 (Zang et al., 2023).
    Language: English
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  • 62
    Publication Date: 2024-01-15
    Description: Probing source mechanisms of natural and induced earthquakes is a powerful tool to unveil associated rupture kinematics. The source processes of failure and slip instability driven by stress loading are affected by fault geometry, but the source ruptures of injection-induced seismicity in relation to fault structures and local stress states remain poorly understood. We have conducted a series of fault reactivation and slip experiments on sandstone samples containing faults with different surface roughness (smooth saw-cut fault and fractured rough fault). We impose progressive fluid injection to induce fault slip, and simultaneously monitor the associated acoustic emission (AE) activity. Using high-resolution AE recordings, we perform full moment tensor inversion of all located AE sources, and investigate the changes of AE source characteristics associated with induced fault slip and their relation to fault roughness. For the complex and rough fault, we observe significant non-double-couple components of AE sources and a high degree of focal mechanism heterogeneity. The temporal changes of AE mechanisms associated with injection-induced fault slip on the smooth fault reveal increasing proportions of double-couple components and decreasing variability of AE focal mechanisms when approaching the onset of slip events. The observed inconsistency between the nodal planes of AE sources and the macroscopic fault plane orientation is attributed to the development of secondary fracture networks surrounding the principal slip surface. We analyze changes in the magnitude-frequency characteristics and source mechanisms of AEs with fault-normal distance, showing that for the smooth (mature) fault, Gutenberg–Richter b-value of on-fault seismicity is lower and focal mechanisms are less heterogeneous, compared to off-fault seismicity. Our results emphasize the important role of roughness-related changes in local fault geometry and associated stress heterogeneity for source mechanisms and rupture kinematics of injection-induced seismicity.
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  • 63
    Publication Date: 2023-12-21
    Description: Interface problems exist widely in various engineering problems and their high-precision simulation is of great importance. A new computational approach for dealing with interface problems is proposed based on the recently developed integral-generalized finite difference (IGFD) scheme. In this method, the research domain is divided into several subdomains by interfaces, and discretization schemes are established independently in each subdomain. A new cross-subdomain integration scheme is introduced to connect these subdomains. Several two-dimensional elasticity models containing material interfaces are studied to test the effectiveness of the proposed method. The results show that the recently proposed approach without the help of discontinuous functions or auxiliary equations that are commonly used in other numerical methods (e.g., extended finite element method and boundary element method) enables obtaining high accuracy and efficiency in interface problems. The proposed method has great potential in the application of material interface problems in solid mechanics and, furthermore, weak discontinuity problems in various fields.
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  • 64
    Publication Date: 2023-12-21
    Description: In space geodetic techniques, the mapping functions (MFs) provide the relationship between zenith and slant tropospheric delays. The MFs are determined under the assumption of spherically layered atmosphere. However, the atmosphere is not spherically layered, and the asymmetry should be considered. Therefore, tropospheric gradients are taken into account. Nevertheless, tropospheric gradients alone can not fully represent the deviation from a spherically layered atmosphere, and hence cm level errors arise especially for low elevation angles. In this study, we present new approaches to modify the wet MF to reduce mismodelling of tropospheric delays. The delays in the study were calculated using ray-tracing algorithm based on ECMWF’s ERA5 dataset. We first analyzed the performances of the new approaches. Then, two Precise Point Positioning (PPP) simulation studies and a real case study were carried out for two different regions namely Germany and Türkiye. According to the results, the proposed approaches reduce the modelling errors up to by a factor 6 for both regions. Besides, simulation studies show that the approaches improve the accuracies of the ZTDs and heights. In the practical application however, we could not find a clear improvement in the PPP analyze and this might be related to the ERA5 which can not be regarded error-free.
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  • 65
    Publication Date: 2024-03-11
    Description: This article summarizes the ground-motion characterization (GMC) model component of the 2022 New Zealand National Seismic Hazard Model (2022 NZ NSHM). The model development process included establishing a NZ-specific context through the creation of a new ground-motion database, and consideration of alternative ground-motion models (GMMs) that have been historically used in NZ or have been recently developed for global application with or without NZ-specific regionalizations. Explicit attention was given to models employing state-of-the-art approaches in terms of their ability to provide robust predictions when extrapolated beyond the predictor variable scenarios that are well constrained by empirical data alone. We adopted a “hybrid” logic tree that combined both a “weightson- models” approach along with backbone models (i.e., metamodels), the former being the conventional approach to GMC logic tree modeling for NSHM applications using published models, and the latter being increasingly used in research literature and site-specific studies. In this vein, two NZ-specific GMMs were developed employing the backbone model construct. All of the adopted subduction GMMs in the logic tree were further modified from their published versions to include the effects of increased attenuation in the back-arc region; and, all but one model was modified to account for the reduction in ground-motion standard deviations as a result of nonlinear surficial site response. As well as being based on theoretical arguments, these adjustments were implemented as a result of hazard sensitivity analyses using models without these effects, which we consider gave unrealistically high hazard estimates.
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  • 66
    Publication Date: 2024-03-11
    Description: Seismicity usually exhibits a non-Poisson spatiotemporal distribution and could undergo nonstationary processes. However, the Poisson assumption is still deeply rooted in current probabilistic seismic hazard analysis models, especially when input catalogs must be declustered to obtain a Poisson background rate. In addition, nonstationary behavior and scarce earthquake records in regions of low seismicity can bias hazard estimates that use stationary or spatially precise forecasts. In this work, we implement hazard formulations using forecasts that trade-off spatial precision to account for overdispersion and nonstationarity of seismicity in the form of uniform rate zones (URZs), which describe rate variability using non-Poisson probabilistic distributions of earthquake numbers. The impact of these forecasts in the hazard space is investigated by implementing a negative- binomial formulation in the OpenQuake hazard software suite, which is adopted by the 2022 Aotearoa New Zealand National Seismic Hazard Model. For a 10% exceedance probability of peak ground acceleration (PGA) in 50 yr, forecasts that only reduce the spatial precision, that is, stationary Poisson URZ models, cause up to a twofold increase in hazard for low-seismicity regions compared to spatially precise forecasts. Furthermore, the inclusion of non-Poisson temporal processes in URZ models increases the expected PGA by up to three times in low-seismicity regions, whereas the effect on high-seismicity is minimal (∼5%). The hazard estimates presented here highlight the relevance, as well as the feasibility, of incorporating analytical formulations of seismicity that go beyond the inadequate stationary Poisson description of seismicity.
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  • 67
    Publication Date: 2024-03-11
    Description: The distribution of earthquakes in time and space is seldom stationary, which could hinder a robust statistical analysis, particularly in low-seismicity regions with limited data. This work investigates the performance of stationary Poisson and spatially precise forecasts, such as smoothed seismicity models (SSMs), in terms of the available training data. Catalog bootstrap experiments are conducted to: (1) identify the number of training data necessary for SSMs to perform spatially better than the least-informative Uniform Rate Zone (URZ) models; and (2) describe the rate temporal variability accounting for the overdispersion and nonstationarity of seismicity. Formally, the strict-stationarity assumption used in traditional forecasts is relaxed into local and incremental stationarity (i.e., a catalog is only stationary in the vicinity of a given time point t) along with self-similar behavior described by a power law. The results reveal rate dispersion up to 10 times higher than predicted by Poisson models and highlight the impact of nonstationarity in assuming a constant mean rate within training-forecast intervals. The temporal rate variability is translated into a reduction of spatial precision by means of URZmodels. First, counting processes are devised to capture rate distributions, considering the rate as a random variable. Second, we devise a data-driven method based on geodetic strain rate to spatially delimit the precision of URZs, assuming that strain/stress rate is related to the timescales of earthquake interactions. Finally, rate distributions are inferred from the available data within each URZ. We provide forecasts for the New Zealand National Seismic Hazard Model update,which can exhibit rates up to ten times higher in low-seismicity regions compared with SSMs. This study highlights the need to consider nonstationarity in seismicity models and underscores the importance of appropriate statistical descriptions of rate variability in probabilistic seismic hazard analysis.
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  • 68
    Publication Date: 2024-03-11
    Description: National-scale seismic hazard models with large logic trees can be difficult to calculate using traditional seismic hazard software. To calculate the complete 2022 revision of the New Zealand National Seismic Hazard Model—Te Tauira Matapae Pūmate Rū i Aotearoa, including epistemic uncertainty, we have developed a method in which the calculation is broken into two separate stages. This method takes advantage of logic tree structures that comprise multiple, independent logic trees from which complete realizations are formed by combination. In the first stage, we precalculate the independent realizations of the logic trees. In the second stage, we assemble the full ensemble of logic tree realizations by combining components from the first stage. Once all realizations of the full logic tree have been calculated, we can compute aggregate statistics for the model. This method benefits both from the reduction in the amount of computation necessary and its parallelism. In addition to facilitating the computation of a large seismic hazard model, the method described can also be used for sensitivity testing of model components and to speed up experimentation with logic tree structure and weights.
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  • 69
    Publication Date: 2024-03-11
    Description: Central America is a seismically active region where six tectonic plates (North America, Caribbean, Cocos, Nazca, Panama, and South America) interact in a subduction zone with transform faults and two triple points. This complex tectonic setting makes the maximum magnitude—Mmax—estimation a challenging task, with the crustal fault earthquakes being the most damaging in the seismic history of Central America. The empirical source scaling relations (ESSR) allow the Mmax of faults to be determined from rupture parameters. In this study, we use a dataset of well-characterized earthquakes in the region, comprising 64 events from 1972 to 2021 with magnitudes between Mw 4.1 and 7.7. The dataset incorporates records of rupture parameters (length, width, area, slip, and magnitude) and information on the faults and aftershocks associated. This database is an important product in itself, and through its use we determine which global relations fit best to our data via a residual analysis. Moreover, based on the best-quality records, we develop scaling relations for Central America (CA-ESSR) for rupture length, width, and area. These new relations were tested and compared with recent earthquakes, and logic trees are proposed to combine the CA-ESSR and the best-fit global relations. Therefore, we estimate the Mmax for 30 faults using the logic tree for rupture length, considering a total rupture of the fault andmultifault scenarios. Our results suggest that in CentralAmerica rupture areas larger than other regions are required to generate the samemagnitudes.We associate this with the shear modulus (μ), which seems to be lower (∼ 30% less) than the global mean values for crustal rocks. Furthermore, considering multifault ruptures, we found several fault systems with potential Mmax ≥Mw 7.0. These findings contribute to a better understanding of regional seismotectonics and to the efficient characterization of fault rupture models for seismic hazards.
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  • 70
    Publication Date: 2024-03-12
    Description: Earthquake precursory processes have been central to scientific inquiry for nearly a century. Recent advancements in earthquake monitoring, geodesy, and data analysis including artificial intelligence, have substantially improved our understanding of how earthquake sequences unfold leading to the mainshock. We examine the available seismological and geodetic evidence describing preparatory processes in 33 earthquake sequences with MW [3.2–9.0] across different tectonic and stress conditions. Our analysis reveals common patterns, and sheds light on the interplay of structural, tectonic and other boundary conditions that influence the dynamics of earthquake sequences, and hence, in the seismo-geodetic observables prior to the mainshock. We place particular emphasis on connecting observed phenomena to the underlying physical processes driving the sequences. From our findings, we propose a conceptual framework viewing earthquake preparation as a process involving several juxtaposed driving physical mechanisms on different temporal and spatial scales, jointly leading to the stress increase in the future epicenter.
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  • 71
    Publication Date: 2024-04-10
    Description: In near-Earth space, a large population of high-energy electrons are trapped by Earth’s magnetic field. These energetic electrons are trapped in the regions called Earth’s ring current and radiation belts. They are very dynamic and show a very strong dependence on solar wind and geomagnetic conditions. These energetic electrons can be dangerous to satellites in the near-Earth space. Therefore, it is very important to understand the mechanisms which drive the dynamics of these energetic electrons. Wave-particle interaction is one of the most important mechanisms. Among the waves that can be encountered by the energetic electrons when they move around our Earth, whistler mode chorus waves can cause both acceleration and the loss of energetic electrons in the Earth's radiation belts and ring current. Using more than 5 years of wave measurements from NASA’s Van Allen Probe mission, Wang et al (2019) developed chorus wave models which depend on magnetic local time (MLT), Magnetic Latitude (MLat), L-shell, and geomagnetic condition index Kp. To quantify the effect of chorus waves on energetic electrons, we calculated the bounce-averaged quasi-linear diffusion coefficients using the chorus wave model developed by Wang et al (2019) and extended to higher latitudes according to Wang and Shprits (2019). Using these diffusion coefficients, we calculated the lifetime of the electrons with an energy range from 1 keV to 2 MeV. In each MLT, we calculate the lifetime for each energy and L-shell using two different methods according to Shprits et al (2007) and Albert and Shprits (2009). We make the calculated electron lifetime database available here. Please notice that the chorus wave model by Wang et al (2019) is valid when Kp 〈= 6. If the user wants to use this lifetime database for Kp 〉6, please be careful and contact the authors.
    Language: English
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  • 72
    Publication Date: 2024-04-10
    Description: Microseismic monitoring represents a key surveillance technology to verify the integrity of subsurface CO storage sites. The precise location of microseismic events is first and foremost a direct and immediate indication of caprock and seal behavior but could also provide insight into CO plume migration. Tiny precursor movements provide diagnostic information about injection-related reservoir and caprock dynamics long before potential seal failure occurs. We present a case study from the Quest CCS facility in Canada, where a variety of different monitoring technologies are employed. We present the different microseismic sensor technologies and array configurations currently installed at the site and compare them against each other with respect to their reliability and effectiveness in providing the required verification information.
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  • 73
    Publication Date: 2024-04-10
    Description: Dynamic rupture simulations generate synthetic waveforms that account for nonlinear source and path complexity. Here, we analyze millions of spatially dense waveforms from 3D dynamic rupture simulations in a novel way to illuminate the spectral fingerprints of earthquake physics. We define a Brune-type equivalent near-field corner frequency (f c ) to analyze the spatial variability of ground-motion spectra and unravel their link to source complexity. We first investigate a simple 3D strike-slip setup, including an asper- ity and a barrier, and illustrate basic relations between source properties and f c varia- tions. Next, we analyze 〉 13,000,000 synthetic near-field strong-motion waveforms generated in three high-resolution dynamic rupture simulations of real earthquakes, the 2019 Mw 7.1 Ridgecrest mainshock, the Mw 6.4 Searles Valley foreshock, and the 1992 Mw 7.3 Landers earthquake. All scenarios consider 3D fault geometries, topography, off-fault plasticity, viscoelastic attenuation, and 3D velocity structure and resolve frequencies up to 1–2 Hz. Our analysis reveals pronounced and localized patterns of elevated f c , specifically in the vertical components. We validate such f c variability with observed near-fault spectra. Using isochrone analysis, we identify the complex dynamic mechanisms that explain rays of elevated f c and cause unexpectedly impulsive, localized, vertical ground motions. Although the high vertical frequencies are also associated with path effects, rupture directivity, and coalescence of multiple rupture fronts, we show that they are dominantly caused by rake-rotated surface-breaking rupture fronts that decel- erate due to fault heterogeneities or geometric complexity. Our findings highlight the potential of spatially dense ground-motion observations to further our understanding of earthquake physics directly from near-field data. Observed near-field f c variability may inform on directivity, surface rupture, and slip segmentation. Physics-based models can identify “what to look for,” for example, in the potentially vast amount of near-field large array or distributed acoustic sensing data.
    Language: English
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  • 74
    Publication Date: 2024-04-10
    Description: Within the framework of the Intercontinental Scientific Drilling Programme (ICDP) ‘Drilling the Eger Rift’ project, five boreholes were drilled in the Vogtland (Germany) and West Bohemia (Czech Republic) regions. Three of them will be used to install high-frequency three-dimensional (3D) seismic arrays. The pilot 3D array is located 1.5 km south of Landwüst (Vogtland). The borehole, with a depth of 402 m, was equipped with eight geophones and a fibre optic cable behind the casing used for distributed acoustic sensing (DAS) measurements. The borehole is surrounded by a surface array consisting of 12 seismic stations with an aperture of 400 m. During drilling, a highly fractured zone was detected between 90 m and 165 m depth and interpreted as a possible fault zone. To characterize the fault zone, two vertical seismic profiling (VSP) experiments with drop weight sources at the surface were conducted. The aim of the VSP experiments was to estimate a local 3D seismic velocity tomography including the imaging of the steep fault zone. Our 3D tomography indicates P-wave velocities between 1500 m/s and 3000 m/s at shallow depths (0–20 m) and higher P-wave velocities of up to 5000 m/s at greater depths. In addition, the results suggest a NW–SE striking low-velocity zone (LVZ; characterized by = 1500–3000 m/s), which crosses the borehole at a depth of about 90–165 m. This LVZ is inferred to be a shallow non-tectonic, steep fault zone with a dip angle of about . The depth and width of the fault zone are supported by logging data as electrical conductivity, core recovery and changes in lithology. In this study, we present an example to test and verify 3D tomography and imaging approaches of shallow non-tectonic fault zones based on active seismic experiments using simple surface drop weights as sources and borehole chains as well as borehole DAS behind casing as sensors, complemented by seismic stand-alone surface arrays.
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  • 75
    Publication Date: 2024-04-10
    Description: Garnet is a prominent mineral in skarn deposits and its rare earth elements (REE) geochemistry is pivotal for understanding skarn mineralization and fluid evolution. In contrast to magmatic and metamorphic garnets, skarn garnets are mainly grossular-andradite in composition. They exhibit variable REE patterns, spanning from notable heavy (H)-REE enrichment to significant light (L)-REE enrichment, accompanied by negative to positive europium (Eu) anomalies. However, the key factors governing REE fractionation in skarn garnets remain uncertain. This study applies the lattice-strain theory (LST) to investigate the influence of crystal chemistry and structure on REE fractionation in garnets from the Lazhushan Fe skarn deposit in eastern China. Our results demonstrate that the garnet-liquid partition coefficient ratios of DLa/DYb significantly increase (up to 5–7 orders of magnitude) with rising andradite content in garnet. This variation underscores the pivotal role of garnet structure in controlling LREE/HREE fractionation. The results further show that partition coefficient ratios of DLa/DSm are strongly dependent on andradite content in garnets, whereas the DGd/DYb ratios only show a weak correlation to the garnet composition. This contrast suggests that fractionation of LREE in garnet is more sensitive to variations of andradite content than HREE. Data compilation of major elements and REE for garnet from the Lazhushan Fe skarn deposit and other skarn deposits worldwide shows that the garnet REE patterns vary from positive through concave to negative shapes with the garnet ranging from grossularitic to andraditic compositions. Such variations in garnet REE patterns are consistent with the results of geochemical modeling based on the LST. This study demonstrates that, through LST equations, the shape of fluid REE patterns can be predicted from garnet REE patterns, and vice versa. Furthermore, the Eu anomaly (Eu/Eu*Grt) in skarn garnet depends mainly on fluid Eu anomaly (Eu/Eu*fluid) and garnet-fluid partition coefficient ratio of D(Eu2+)/D(Eu3+) with the latter being influenced by garnet composition. These findings highlight the critical role of crystal chemistry and structure in garnet REE fractionation, enhancing our ability to utilize garnet REE in tracing the origin and evolution of skarn-forming fluids.
    Language: English
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  • 76
    Publication Date: 2024-04-10
    Description: Tsunamigenic earthquakes pose considerable risks, both economically and socially, yet earthquake and tsunami hazard assessments are typically conducted separately. Earthquakes associated with unexpected tsunamis, such as the 2018 Mw  7.5 strike-slip Sulawesi earthquake, emphasize the need to study the tsunami potential of active submarine faults in different tectonic settings. Here, we investigate physics-based scenarios combining simulations of 3D earthquake dynamic rupture and seismic wave propagation with tsunami generation and propagation. We present time-dependent modeling of one-way linked and 3D fully coupled earthquakes and tsunamis for the ∼ 100 km long Húsavík–Flatey Fault Zone (HFFZ) in North Iceland. Our analysis shows that the HFFZ has the potential to generate sizable tsunamis. The six dynamic rupture models sourcing our tsunami scenarios vary regarding hypocenter location, spatiotemporal evolution, fault slip, and fault structure complexity but coincide with historical earthquake magnitudes. Earthquake dynamic rupture scenarios on a less segmented fault system, particularly with a hypocenter location in the eastern part of the fault system, have a larger potential for local tsunami generation. Here, dynamically evolving large shallow fault slip (∼ 8 m), near-surface rake rotation (± 20∘), and significant coseismic vertical displacements of the local bathymetry (± 1 m) facilitate strike-slip faulting tsunami generation. We model tsunami crest to trough differences (total wave heights) of up to ∼ 0.9 m near the town Ólafsfjörður. In contrast, none of our scenarios endanger the town of Akureyri, which is shielded by multiple reflections within the narrow Eyjafjörður bay and by Hrísey island. We compare the modeled one-way linked tsunami waveforms with simulation results using a 3D fully coupled approach. We find good agreement in the tsunami arrival times and location of maximum tsunami heights. While seismic waves result in transient motions of the sea surface and affect the ocean response, they do not appear to contribute to tsunami generation. However, complex source effects arise in the fully coupled simulations, such as tsunami dispersion effects and the complex superposition of seismic and acoustic waves within the shallow continental shelf of North Iceland. We find that the vertical velocity amplitudes of near-source acoustic waves are unexpectedly high – larger than those corresponding to the actual tsunami – which may serve as a rapid indicator of surface dynamic rupture. Our results have important implications for understanding the tsunamigenic potential of strike-slip fault systems worldwide and the coseismic acoustic wave excitation during tsunami generation and may help to inform future tsunami early warning systems.
    Language: English
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  • 77
    Publication Date: 2024-04-10
    Description: The epidemic-type aftershock sequence (ETAS) model is the state-of-the-art approach for modelling short-term earthquake clustering and is preferable for short-term aftershock forecasting. However, due to the large variability of different earthquake sequences, the model parameters must be adjusted to the local seismicity for accurate forecasting. Such an adjustment based on the first aftershocks is hampered by the incompleteness of earthquake catalogues after a mainshock, which can be explained by a blind period of the seismic networks after each earthquake, during which smaller events with lower magnitudes cannot be detected. Assuming a constant blind time, direct relationships based only on this additional parameter can be established between the actual seismicity rate and magnitude distributions and those that can be detected. The ETAS-incomplete (ETASI) model uses these relationships to estimate the true ETAS parameters and the catalogue incompleteness jointly. In this study, we apply the ETASI model to the SE Türkiye earthquake sequence, consisting of a doublet of M 7.7 and M 7.6 earthquakes that occurred within less than half a day of each other on 6 February 2023. We show that the ETASI model can explain the catalogue incompleteness and fits the observed earthquake numbers and magnitudes well. A pseudo-prospective forecasting experiment shows that the daily number of detectable m ≥ 2 can be well predicted based on minimal and incomplete information from early aftershocks. However, the maximum magnitude (Mmax ) of the next day’s aftershocks would have been overestimated due to the highly variable b value within the sequence. Instead, using the regional b value estimated for 2000–2022 would have well predicted the observed Mmax  values.
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  • 78
    Publication Date: 2024-04-10
    Description: Massive sediment pulses in catchments are a key alpine multi-risk component. Substantial sediment redistribution in alpine catchments frequently causes flooding, river erosion, and landsliding and affects infrastructure such as dam reservoirs as well as aquatic ecosystems and water quality. While systematic rock slope failure inventories have been collected in several countries, the subsequent cascading sediment redistribution is virtually unaccessed. For the first time, this contribution reports the massive sediment redistribution triggered by the multi-stage failure of more than 130 000 m3 from the Hochvogel dolomite peak during the summer of 2016. We applied change detection techniques to seven 3D-coregistered high-resolution true orthophotos and digital surface models (DSMs) obtained through digital aerial photogrammetry later optimized for precise volume calculation in steep terrain. The analysis of seismic information from surrounding stations revealed the temporal evolution of the cliff fall. We identified the proportional contribution of 〉 600 rockfall events (〉 1 m3) from four rock slope catchments with different slope aspects and their volume estimates. In a sediment cascade approach, we evaluated erosion, transport, and deposition from the rock face to the upper channelized erosive debris flow channel, then to the widened dispersive debris flow channel, and finally to the outlet into the braided sediment-supercharged Jochbach river. We observe the decadal flux of more than 400 000 m3 of sediment, characterized by massive sediment waves that (i) exhibit reaction times of 0–4 years in response to a cliff fall sediment input and relaxation times beyond 10 years. The sediment waves (ii) manifest with faster response times of 0–2 years in the upper catchment and over 2 years in the lower catchments. The entire catchment (iii) undergoes a rapid shift from sedimentary (102–103 mm a−1) to massive erosive regimes (102 mm a−1) within single years, and the massive sediment redistribution (iv) shows limited dependency on rainfall frequency and intensity. This study provides generic information on spatial and temporal patterns of massive sediment pulses in highly sediment-charged alpine catchments.
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  • 79
  • 80
    Publication Date: 2024-04-08
    Description: The ocean basins contain numerous volcanic ridges, seamounts and large igneous provinces (LIPs). Numerous studies have focused on the origin of seamount chains and LIPs but much less focus has been applied to understanding the genesis of large volcanic structures formed from a combination or series of volcanic drivers. Here we propose the term Oceanic Mid-plate Superstructures (OMS) to describe independent bathymetric swells or volcanic structures that are constructed through superimposing pulses of volcanism, over long time periods and from multiple sources. These sources can represent periods when the lithosphere drifted over different mantle plumes and/or experienced pulses of volcanism associated with shallow tectonic drivers (e.g. plate flexure; lithospheric extension). Here we focus on the Melanesian Border Plateau (MBP), one example of an OMS that has a complex and enigmatic origin. The MBP is a region of shallow Pacific lithosphere consisting of high volumes of volcanic guyots, ridges and seamounts that resides on the northern edge of the Vitiaz Lineament. Here we reconcile recently published constraints to build a comprehensive volcanic history of the MBP. The MBP was built through four distinct episodes: (1) Volcanism associated with the Louisville hotspot likely generating Robbie Ridge and some Cretaceous seamounts near the MBP. (2) Construction of oceanic islands and seamounts during the Eocene when the lithosphere passed over the Rurutu-Arago hotspot. (3) Reactivation of previous oceanic islands/seamounts and construction of new volcanos in the Miocene when the lithosphere passed over the Samoa hotspot. (4) Miocene to modern volcanism driven by lithospheric deformation and/or westward entrainment of enriched plume mantle due to toroidal mantle flow driven by the rollback of the Pacific plate beneath the Tonga trench. The combination of these processes is responsible for ∼222,000 km2 of intraplate volcanism in the MBP and indicates that this OMS was constructed from multiple volcanic drivers.
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  • 81
    Publication Date: 2024-04-08
    Description: We compared the performance of DREAM3D simulations in reproducing the long‐term radiation belt dynamics observed by Van Allen Probes over the entire year of 2017 with various boundary conditions (BCs) and model inputs. Specifically, we investigated the effects of three different outer boundary conditions, two different low‐energy boundary conditions for seed electrons, four different radial diffusion (RD) coefficients (DLL), four hiss wave models, and two chorus wave models from the literature. Using the outer boundary condition driven by GOES data, our benchmark simulation generally well reproduces the observed radiation belt dynamics inside L* = 6, with a better model performance at lower μ than higher μ, where μ is the first adiabatic invariant. By varying the boundary conditions and inputs, we find that: (a) The data‐driven outer boundary condition is critical to the model performance, while adding in the data‐driven seed population doesn't further improve the performance. (b) The model shows comparable performance with DLL from Brautigam and Albert (2000, https://doi.org/10.1029/1999ja900344), Ozeke et al. (2014, https://doi.org/10.1002/2013ja019204), and Liu et al. (2016, https://doi.org/10.1002/2015gl067398), while with DLL from Ali et al. (2016, https://doi.org/10.1002/2016ja023002) the model shows less RD compared to data. (c) The model performance is similar with data‐based hiss models, but the results show faster loss is still needed inside the plasmasphere. (d) The model performs similarly with the two different chorus models, but better capturing the electron enhancement at higher μ using the Wang et al. (2019, https://doi.org/10.1029/2018ja026183) model due to its stronger wave power, since local heating for higher energy electrons is under‐reproduced in the current model.
    Language: English
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  • 82
    Publication Date: 2024-04-08
    Description: Rare metals (Nb, Ta, Y, Zr, Sn, U, W and REE) are economically important and new supplies need to be found. In order to understand Neoproterozoic rare metal granites of the Arabian–Nubian Shield (ANS), six samples from five rare-metal mineralized alkali feldspar granites, syenogranites and granodiorite from the Central and SE Desert of Egypt were studied for zircon U–Pb ages and O-isotopic compositions as well as whole-rock Sr- and Nd- and alkali feldspar Pb-isotopic compositions. These are transitional between I-type and A-type granites, mostly high-K calc-alkaline, peraluminous granites with gullwing-shaped REE patterns and strongly negative Eu anomalies. Four granites gave mantle-like zircon 18OV-SMOW between 4.2 and 5.96‰ and yielded ages of 628–633 Ma. This is about when subduction-related magmatism began to be replaced by collision-related magmatism. Igla Ahmr granites are older, formed at 691.7–678.9 Ma with 18OV-SMOW c. 5.95‰. All have positive initial Nd values (+3.3 to +6.9) typical for mantle and juvenile crust. Pb isotopic compositions are unusually radiogenic compared with unmineralized ANS granitic rocks. The data indicate similar magmatic sources for ANS mineralized and unmineralized granites. Exploration for other rare-metal mineralized granites in the ANS should focus on bodies with similar characteristics
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  • 83
    Publication Date: 2024-04-08
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  • 84
    Publication Date: 2024-04-08
    Description: The Tieshajie Cu deposit, located in the northeastern part of the Qin-Hang Metallogenic Belt (QHMB), South China, has long been regarded as a representative Meso-Neoproterozoic volcanogenic massive sulfide (VMS) deposit. Here we present a hydrothermal titanite U-Pb age, Re-Os and in-situ S-Cu isotope data for chalcopyrite to constrain the timing and ore genesis of the Tieshajie deposit. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating of titanite from the disseminated Cu ore yielded a weighted mean 206Pb/238U age of 160.1 ± 4.4 Ma. Chalcopyrite from different ore types has low 187Os/188Os (0.85–3.60) and 187Re/188Os (46.1–614.0) ratios, combined with initial 187Os/188Os (0.74–2.00), excluding a mantle source. A Re-Os isochron age (188 ± 30 Ma) for five chalcopyrite samples is consistent with the titanite U-Pb age within errors. Moreover, the variations in Cu isotope compositions (δ65Cu: −1.13 to +0.12 ‰) and δ34S values (+3.8 to +7.7 ‰) of chalcopyrite are inconsistent with those reported from the ancient VMS deposits in previous studies. Therefore, our results are indicative of a Late Jurassic magmatic-hydrothermal origin instead of a VMS origin for the Tieshajie deposit. In combination with previous studies, we propose that the Tieshajie Cu deposit belongs to the distal part of the Mid-Late Jurassic (170–150 Ma) porphyry-skarn Cu mineralization event in the QHMB, likely triggered by the subduction of the Paleo-Pacific plate during the Late Mesozoic. This study also has new insights into the genesis of Cu mineralization in the QHMB and further provides implications for future exploration.
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  • 85
    Publication Date: 2024-04-08
    Description: The use of intermittent renewable energy sources is of great importance for reducing greenhouse gas emissions. Medium-deep borehole thermal energy storage systems (MD-BTES) represent an economic solution. At the Technical University of Darmstadt, Germany, an MD-BTES consisting of three 750 m deep borehole heat exchangers was constructed as a demonstrator. Before construction, a comprehensive dataset consisting of electrical conductivity tomography profiles, gravity measurements, 2D seismic profiles, and petrophysical data of nearby outcrops was obtained. In the seismic data, multiple geological facies and faults could be identified and correlated with lithologies based on the gravimetric dataset and drilling data. The data facilitated optimization of the drilling work, modeling, and planning of the system. In this project, the combination of 2D-seismic with well data proved to be especially useful for detailed site characterization, while electrical resistivity tomography and gravimetry provided additional constraints on the subsurface and were used for data regionalization. The results emphasize that at least one exploratory well should be included when planning medium-deep reservoirs in potentially heterogeneous crystalline settings with insufficient outcrop data. The experiences made during this work greatly benefit the planning and execution of future MD-BTES projects by facilitating the development of a cost-efficient site characterization strategy.
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  • 86
    Publication Date: 2024-04-05
    Description: This study conducts mineralogical and chemical investigations on the oldest achondrite, Erg Chech 002 (∼4565 million yr old). This meteorite exhibits a disequilibrium igneous texture characterized by high-Mg-number (atomic Mg/(Mg + Fe2+)) orthopyroxene xenocrysts (Mg number = 60–80) embedded in an andesitic groundmass. Our research reveals that these xenocrysts were early formed crystals, loosely accumulated or scattered in the short-period magma ocean on the parent body. Subsequently, these crystals underwent agitation due to the influx of external materials. The assimilation of these materials enriched the 16O component of the magma ocean and induced a relatively reduced state. Furthermore, this process significantly cooled the magma ocean and inhibited the evaporation of alkali elements, leading to elevated concentrations of Na and K within the meteorite. Our findings suggest that the introduced materials are probably sourced from the reservoirs of CR clan meteorites, indicating extensive transport and mixing of materials within the early solar system.
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  • 87
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    In:  Earth Surface Dynamics
    Publication Date: 2024-04-05
    Description: The width of fluvial valley floors is a key parameter to quantifying the morphology of mountain regions. Valley floor width is relevant to diverse fields including sedimentology, fluvial geomorphology, and archaeology. The width of valleys has been argued to depend on climatic and tectonic conditions, on the hydraulics and hydrology of the river channel that forms the valley, and on sediment supply from valley walls. Here, we derive a physically based model that can be used to predict valley width and test it against three different datasets. The model applies to valleys that are carved by a river migrating laterally across the valley floor. We conceptualize river migration as a Poisson process, in which the river changes its direction stochastically at a mean rate determined by hydraulic boundary conditions. This approach yields a characteristic timescale for the river to cross the valley floor from one wall to the other. The valley width can then be determined by integrating the speed of migration over this timescale. For a laterally unconfined river that is not uplifting, the model predicts that the channel-belt width scales with river flow depth. Channel-belt width corresponds to the maximum width of a fluvial valley. We expand the model to include the effects of uplift and lateral sediment supply from valley walls. Both of these effects lead to a decrease in valley width in comparison to the maximum width. We identify a dimensionless number, termed the mobility–uplift number, which is the ratio between the lateral mobility of the river channel and uplift rate. The model predicts two limits: at high values of the mobility–uplift number, the valley evolves to the channel-belt width, whereas it corresponds to the channel width at low values. Between these limits, valley width is linked to the mobility–uplift number by a logarithmic function. As a consequence of the model, valley width increases with increasing drainage area, with a scaling exponent that typically has a value between 0.4 and 0.5, but can also be lower or higher. We compare the model to three independent datasets of valleys in experimental and natural uplifting landscapes and show that it closely predicts the first-order relationship between valley width and the mobility–uplift number.
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  • 88
    Publication Date: 2024-04-05
    Description: Türkiye relies on coal-fired power plants for approximately 18 GW of annual electricity generation, with significantly higher CO2 emissions compared to geothermal power plants. On the other hand, geothermal energy resources, such as Enhanced Geothermal Systems (EGS) and hydrothermal systems, offer low CO2 emissions and baseload power, making them attractive clean energy sources. Radiogenic granitoid, with high heat generation capacity, is a potential and cleaner energy source using EGS. The Anatolian plateau hosts numerous tectonic zones with plutonic rocks containing high concentrations of radioactive elements, such as the Central Anatolian Massif. This study evaluates the power generation capacity of the Hamit granitoid (HG) and presents a thermo-hydraulic-mechanical (THM) model for a closed-loop geothermal well for harnessing heat from this granitoid. A sensitivity analysis based on fluid injection rates and wellbore length emphasizes the importance of fluid resident time for effective heat extraction. Closed-loop systems pose fewer geomechanical risks than fractured systems and can be developed through site selection, system design, and monitoring. Geothermal wellbore casing material must withstand high temperatures, corrosive environments, and should have low thermal conductivity. The HG exhibits the highest heat generation capacity among Anatolian granitoid intrusions and offers potential for sustainable energy development through EGS, thereby reducing CO2 emissions.
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  • 89
    Publication Date: 2024-04-09
    Description: Low Earth Orbit satellites offer extensive data of the radiation belt region, but utilizing these observations is challenging due to potential contamination and difficulty of intercalibration with spacecraft measurements at Highly Elliptic Orbit that can observe all equatorial pitch-angles. This study introduces a new intercalibration method for satellite measurements of energetic electrons in the radiation belts using a Data assimilation (DA) approach. We demonstrate our technique by intercalibrating the electron flux measurements of the National Oceanic and Atmospheric Administration (NOAA) Polar-orbiting Operational Environmental Satellites (POES) NOAA-15,-16,-17,-18,-19, and MetOp-02 against Van Allen Probes observations from October 2012 to September 2013. We use a reanalysis of the radiation belts obtained by assimilating Van Allen Probes and Geostationary Operational Environmental Satellites observations into 3-D Versatile Electron Radiation Belt (VERB-3D) code simulations via a standard Kalman filter. We compare the reanalysis to the POES data set and estimate the flux ratios at each time, location, and energy. From these ratios, we derive energy and L* dependent recalibration coefficients. To validate our results, we analyze on-orbit conjunctions between POES and Van Allen Probes. The conjunction recalibration coefficients and the data-assimilative estimated coefficients show strong agreement, indicating that the differences between POES and Van Allen Probes observations remain within a factor of two. Additionally, the use of DA allows for improved statistics, as the possible comparisons are increased 10-fold. Data-assimilative intercalibration of satellite observations is an efficient approach that enables intercalibration of large data sets using short periods of data.
    Language: English
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  • 90
    Publication Date: 2024-04-09
    Description: Investigating past interglacial climatic and environmental changes can enhance our understanding of the natural rates and ranges of climate variability under interglacial boundary conditions. However, comparing past interglacial palaeoclimate records from different regions and archives is often complicated by differing and uncertain chronologies. For instance, the duration of the Last Interglacial in Europe is still controversial as southern European palaeoclimate records suggest a duration of ~16 500–18 000 years, while a length of only ~11 000 years in northern-central Europe was previously inferred from the analysis of partly annually laminated (varved) palaeolake sediments recovered at Bispingen, northern Germany. To resolve this discrepancy, we here present sediment microfacies, geochemistry and pollen data from a new sediment core from the Bispingen palaeolake sediment succession, covering the entire Last Interglacial (Eemian) and the earliest part of the Last Glacial (Weichselian). In particular, we provide evidence that the duration of the Last Interglacial at Bispingen must have been hitherto underestimated due to the investigation of an incomplete sediment core. Using microscopic varve counting and sedimentation rate estimates for non-varved sections on the new sediment core, we show that the Eemian in northern-central Europe probably lasted at least ~15 000 years, about 4000 years longer than previously thought. This new duration estimate is in much better agreement with results from southern European palaeoclimate records, clarifying the enigma of a steep trans-European vegetation gradient for several millennia at the end of the Last Interglacial.
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  • 91
    Publication Date: 2024-03-20
    Description: Drainage divides separate Earth’s surface into individual river basins. Divide migration impacts the evolution of landforms, regional climate, ecosystems and biodiversity. In this Review, we assess the processes and dynamics of divide migration and offer insights into the impact on climate and biodiversity. Drainage divides are not static: they can move through the processes of gradual migration that is continuous in unsteady landscapes, or sudden through infrequent river capture events. Divides tend to move in the direction of slower erosion, faster uplift or with horizontal tectonic advection, with rates typically ranging between 0.001 and 10 mm year−1, and a global average of 0.6 mm year−1. Evidence of river capture, such as a sharp change in flow direction with an upstream waterfall, can constrain divide migration history. Topographic metrics, such as cross-divide steepness, can predict the migration of drainage divides towards directions with a lower topographic steepness. Divide migration influences the spatial distribution of regional precipitation, temperature and topographic connectivity between species, thereby affecting biodiversity. For example, freshwater fish can migrate into a new drainage basin through river capture, potentially increasing the species richness. Future research should couple advanced landscape evolution models and observations from field and remote sensing to better investigate divide migration dynamics.
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  • 92
    Publication Date: 2024-03-20
    Description: Reusing deep wells whether from oil- and gas or geothermal energy production, after years of inactivity can be economically beneficial for the geothermal industry. This study examines the processes that occur in an abandoned well and their impact on reservoir performance. The Groß Sch¨onebeck geothermal research well Gt GrSk 4/05 was reopened after a seven-year production stop to characterize its hydraulic and hydrochemical properties. It targets a reservoir of Rotliegend sandstone and underlying volcanic rocks at a depth of approximately 4000 m. Prior to the hydraulic test, gas samples were collected at the wellhead outlet. These samples showed a significant increase in methane content from approximately 10–15 vol.-% as measured between 2009 and 2013 to 65 vol.-% as measured currently). The objective of this study was to identify the processes responsible for the increase in methane and to assess their impact on well productivity. Well productivity was evaluated through a slug-withdrawal test, followed by the collection of two fluid samples at depths of 1500 m and 4000 m. The chemical composition of the gas and liquid samples was analyzed along with the microbial community. Isotopes of sulfur (34S) and oxygen (18O) were measured in dissolved sulfate and 13C isotopes were measured in the gas phase of hydrocarbons. The particles separated from the suspension of the collected fluid samples were analyzed by scanning electron microscopy. Compared to previous analyses of fluid samples from this well, the methane content has significantly increased and hydrogen sulfide has been detected in the gas phase. Additionally, sulfides of copper and iron were found in the black-colored suspension from the deep-fluid sample taken at 4000 m. The two samples also differ significantly in their organic carbon content, with the sample from 1500 m containing a high amount (135 mg C/L) and at the sample from 4000 m containing a relatively low amount (5 mg C/L). Remarkably, despite the extreme conditions (150 ◦C; 265 g/L TDS at 4000 m), both samples contained several bacterial and fungal genera). Isotope analysis of hydrocarbons in the gas phase indicated mixed methane production from both, thermogenic and biogenic processes. The strong negative 34S of sulfate in the liquid samples rather suggested a thermogenic process of sulfate reduction. It is assumed that several processes occur along the wellbore, including microbial steel corrosion of the well casing (which provides hydrogen, methane, organic carbon, and iron), thermal sulfate reduction, and inflow of formation gases. However, despite the observation of complex geochemical and microbial reactions in the well, the results from the slug withdrawal test indicated no significant change in well productivity (0.6 m3/h*MPa) since the last test in 2014.
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  • 93
    Publication Date: 2024-03-20
    Description: Flood losses have steadily increased in the past and are expected to grow even further owing to climate and socioeconomic change. The reduction of flood vulnerability, for example, through adaptation, plays a key role in the mitigation of future flood risk. However, lacking knowledge about vulnerability dynamics, which arise from the interaction between floods and the ensuing response by society, limits the scope of current risk projections. We present a socio-hydrological method for flood risk assessment that simulates the interaction between society and flooding continuously, including changes in vulnerability through collective (structural) and private (non structural) measures. Our probabilistic approach quantifies uncertainties and exploits empirical data to chart risk dynamics including how society copes with flooding. In a case study for the commercial sector in Dresden, Germany, we show that increased adaptation is necessary to counteract the expected four-fold growth in flood risk due to transient hydroclimatic and socioeconomic boundary conditions. We further use our holistic approach to identify solutions for effective long-term adaptation, demonstrating that integrated adaptation strategies (i.e., combined structural and non structural measures) can reduce the average risk by up to 60% at the study site. Ultimately, our case study highlights the benefit of the model for robust flood risk assessment as it can capture unintended, adverse feedbacks of adaptation measures such as the levee effect. Consequently, our socio-hydrological method contributes to a more systemic and reliable flood risk assessment that can inform adaptation planning by exploring the possible system evolutions comprehensively including unlikely futures.
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  • 94
    Publication Date: 2024-03-20
    Description: Primary granitic melt inclusions are trapped in garnets of eclogites in the garnet peridotite body of Pfaffenberg, Granulitgebirge (Bohemian Massif, Germany). These polycrystalline inclusions, based on their nature and composition, can be called nanogranitoids and contain mainly phlogopite/biotite, kumdykolite, quartz/rare cristobalite, a phase with the main Raman peak at 412 cm-1, a phase with the main Raman peak at 430 cm-1, osumilite and plagioclase. The melt is hydrous, peraluminous and granitic and significantly enriched in large ion lithophile elements (LILE), Th, U, Li, B and Pb. The melt major element composition resembles that of melts produced by the partial melting of metasediments, as also supported by its trace element signature characterized by elements (LILE, Pb, Li and B) typical of the continental crust. These microstructural and geochemical features suggest that the investigated melt originated in the subducted continental crust and interacted with the mantle to produce the Pfaffenberg eclogite. Moreover, in situ analyses and calculations based on partition coefficients between apatite and melt show that the melt was also enriched in Cl and F, pointing toward the presence of a brine during melting. The melt preserved in inclusions can thus be regarded as an example of a metasomatizing agent present at depth and responsible for the interaction between the crust and the mantle. Chemical similarities between this melt and other metasomatizing melts measured in other eclogites from the Granulitgebirge and Erzgebirge, in addition to the overall similar enrichment in trace elements observed in other metasomatized mantle rocks from central Europe, suggest an extended crustal contamination of the mantle beneath the Bohemian Massif during the Variscan orogeny.
    Language: English
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  • 95
    Publication Date: 2024-03-20
    Description: U–Pb geochronology of shocked monazite can be used to date hypervelocity impact events. Impact-induced recrystallisation and formation of mechanical twins in monazite have been shown to result in radiogenic Pb loss and thus constrain impact ages. However, little is known about the effect of porosity on the U–Pb system in shocked monazite. Here we investigate monazite in two impact melt rocks from the Hiawatha impact structure, Greenland by means of nano- and micrometre-scale techniques. Microstructural characterisation by scanning electron and transmission electron microscopy imaging and electron backscatter diffraction reveals shock recrystallisation, microtwins and the development of widespread micrometre- to nanometre-scale porosity. For the first time in shocked monazite, nanophases identified as cubic Pb, Pb3O4, and cerussite (PbCO3) were observed. We also find evidence for interaction with impact melt and fluids, with the formation of micrometre-scale melt-bearing channels, and the precipitation of the Pb-rich nanophases by dissolution–precipitation reactions involving pre-existing Pb-rich high-density clusters. To shed light on the response of monazite to shock metamorphism, high-spatial-resolution U–Pb dating by secondary ion mass spectrometry was completed. Recrystallised grains show the most advanced Pb loss, and together with porous grains yield concordia intercept ages within uncertainty of the previously established zircon U–Pb impact age attributed to the Hiawatha impact structure. Although porous grains alone yielded a less precise age, they are demonstrably useful in constraining impact ages. Observed relatively old apparent ages can be explained by significant retention of radiogenic lead in the form of widespread Pb nanophases. Lastly, we demonstrate that porous monazite is a valuable microtexture to search for when attempting to date poorly constrained impact structures, especially when shocked zircon or recrystallised monazite grains are not present.
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  • 96
    Publication Date: 2024-03-20
    Description: The response of evapotranspiration to anthropogenic warming is of critical importance for the water and carbon cycle. Contradictory conclusions about evapotranspiration changes are caused primarily by their brevity in time and sparsity in space, as well as the strong influence of internal variability. Here, we present the first gridded reconstruction of the summer (June, July, and August) vapor pressure deficit (VPD) for the past 4 centuries at the European level. This gridded reconstruction is based on 26 European tree ring oxygen isotope records and is obtained using a random forest approach. According to validation scores obtained with the Nash–Sutcliffe model efficiency, our reconstruction is robust over large parts of Europe since 1600, in particular for the westernmost and northernmost regions, where most tree ring records are located. Based on our reconstruction, we show that from the mid-1700s a trend towards higher summer VPD occurred in central Europe and the Mediterranean region that is related to a simultaneous increase in temperature and decrease in precipitation. This increasing summer VPD trend continues throughout the observational period and in recent times. Moreover, our summer VPD reconstruction helps to visualize the local and regional impacts of the current climate change, as well as to minimize statistical uncertainties of historical VPD variability. This paper provides also new insights into the relationship between summer VPD and large-scale atmospheric circulation, and we show that summer VPD has two preferred modes of variability, namely a NW–SE dipole-like mode and a N–S dipole-like mode. Furthermore, the interdisciplinary use of the data should be emphasized, as summer VPD is a crucial parameter for many climatological feedback processes in the Earth's surface system. The reconstructed summer VPD gridded data over the last 400 years are available at the following link: https://doi.org/10.5281/zenodo.5958836 (Balting et al., 2022).
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  • 97
    Publication Date: 2024-03-18
    Description: We provide a lithospheric-scale conductive thermal model of subsurface below the State of Brandenburg (Northeast German Basin (NEGB), Germany), represented in three variants: An original thermal model with the resolved Rupelian layer calculated using Geological Modelling System (GMS), a supplement to Noack et al. (2012); An original thermal model without the resolved Rupelian layer calculated using Geological Modelling System (GMS), a supplement to Noack et al. (2013); A reproduced thermal model without the resolved Rupelian layer calculated using the software GOLEM (Jacquey & Cacace, 2017). Both original and reproduced models cover the same area of 250 km in E-W direction and 210 km in N–S direction. The first two original models are discussed in the mentioned papers Noack et al. (2012) and Noack et al. (2013), whereas the third model is provided for reproducibility purposes. Models contain information on calculated temperatures and relevant physical properties from the quaternary layer down to the Lithosphere-Asthenosphere Boundary (LAB). There are two versions of the stratigraphic layering in the 3D structural model which helps to calculates the thermal fields: one with the Rupelian clay layers consisting of 15 layers and one without them consisting of 17 layers. The coordinate system used is Gauss Krueger zone 4. The model without the resolved Rupelian layer (variant 1) is a supplement to the following published paper: Sensitivity of 3D thermal models to the choice of boundary conditions and thermal properties: a case study for the area of Brandenburg (NE German Basin) The model with the resolved Rupelian layer (variant 2) is a supplement to another published paper: Influence of fluid flow on the regional thermal field: Results from 3D numerical modelling for the area of Brandenburg (North German Basin) In variant 3, we also provide results of our attempt at reproducing of the model from the variant 2. In addition, we provide input files for reproducibility. The contents and structure of the provided files are described in the Technical Information section.
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  • 98
    Publication Date: 2024-03-18
    Description: Unconsolidated, undrained triaxial deformation tests were performed on sandy facies Opalinus Clay at 50 MPa confining pressure to characterize the effect of water and microfabric orientation on the deformation behavior, mechanical properties, and P-wave velocity evolution. Dry and wet (≈ 8 and 〉 95% initial water saturation, respectively) samples with 12.6 ± 0.4 vol% porosity were deformed parallel and perpendicular to the bedding direction at a constant strain rate of 5 × 10–6 s−1. Dry samples revealed semi-brittle behavior and exhibited strain localization at failure, while deformation was more ductile at saturated conditions, promoting stable, slow faulting. Peak strength, Young’s modulus, and number of cumulative acoustic emissions decreased significantly for wet samples compared to dry samples; the opposite was observed for Poisson’s ratio. P-wave velocity anisotropy was significantly altered by differential stress, primarily due to the interplay between pore and fracture closure and stress-induced microcrack formation. For samples that were deformed perpendicular to bedding, we observed a reduction and reversal of P-wave velocity anisotropy with increasing differential stress, whereas anisotropy of parallel samples increased. The results suggest that water saturation reduces the pressure at the brittle-ductile transition and that the elastic properties and anisotropy of sandy facies Opalinus Clay can be significantly altered in an anisotropic stress field, e.g., adjacent to fault zones or tunnel excavations. Changes in elastic anisotropy are primarily controlled by the orientation between the pre-existing microfabric and the maximum principal stress direction, stress magnitude, and the degree of water saturation.
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  • 99
    Publication Date: 2024-03-18
    Description: Electron and ion fluxes at energies of ∼ 10 keV - 1 MeV can change by orders of magnitude during geomagnetically active periods. This can lead to intensification of particle precipitation into the Earth's atmosphere. The process further affects atmospheric chemistry, which may impact weather and climate on the Earth’s surface. In this study, we concentrate on ring current electrons, and investigate precipitation mechanisms using a numerical model based on the Fokker-Planck equation. We focus on a study of the main precipitation mechanisms, and their connection with atmospheric parameters. We investigate the 17 March 2013 storm using the convection-diffusion 4-Dimensional Versatile Electron Radiation Belt (VERB-4D) code, that allows us to quantify the impact of the storm on the electron ring current, and the resulting electron precipitation. We validate our results against observations from the Polar Operational Environmental Satellites (POES) mission, the low Earth orbiting meteorological satellites National Oceanic and Atmospheric Administration (NOAA-15,-16,-17,-18,-19), and Meteorological Operational Satellite MetOp-02, as well as the Van Allen Probes, and produce a data set of precipitating fluxes that covers an energy range from 10 keV to 1 MeV. We calculate the altitude-dependent atmospheric ionization rates, a prerequisite for atmospheric models to estimate effects of geomagnetically active periods on chemical and physical variability of the atmosphere at high latitudes. Atmospheric ionization rates are validated against Atmospheric Ionization during Substorm (AIMOS 2.1-Aisstorm) and Special Sensor Ultraviolet Spectrographic Imagers (SSUSI) values, and show good agreement at high geomagnetic latitudes during the storm time.
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  • 100
    Publication Date: 2024-03-18
    Description: Form and function are two major characteristics of hydrological systems. While form summarizes the structure of the system, function represents the hydrological response. Little is known about how these characteristics evolve and how form relates to function in young hydrological systems. We investigated how form and function evolve during the first millennia of landscape evolution. We analyzed two hillslope chronosequences in glacial forelands, one developed from siliceous and the other from calcareous parent material. Variables describing hillslope form included soil physical properties, surface, and vegetation characteristics. Variables describing hydrological function included soil water response times, soil water storage, drainage, and dominant subsurface flow types. We identified links between form and hydrological function via cluster analysis. Clusters identified based on form were compared in terms of their hydrological functioning. The comparison of the two different parent materials shows how strongly landscape evolution is controlled by the underlying geology. Soil pH appears to be a key variable influencing vegetation, soil formation and subsequently hydrology. At the calcareous site, the high buffering capacity of the soil leads to less soil formation and fast, vertical subsurface water transport dominates the water redistribution even after more than 10,000 years of landscape evolution. At the siliceous site, soil acidification results in accumulation of organic material, a high water storage capacity, and in podsolization. Under these conditions water redistribution changes from vertical subsurface water transport at the young age classes to water storage in the organic surface layer and lateral subsurface water transport within 10,000 years.
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