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  • 1
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    Platinum-group element abundances in background samples and the K-T boundary interval from DSDP Hole 91-596 (Table 2)
    PANGAEA
    In:  Supplement to: Evans, Noreen J; Ahrens, Thomas J; Gregoire, D C (1995): Fractionation of ruthenium from iridium at the Cretaceous-Tertiary boundary. Earth and Planetary Science Letters, 134(1-2), 141-153, https://doi.org/10.1016/0012-821X(95)00117-U
    Details
    Publikationsdatum: 2023-06-27
    Beschreibung: New data on Ru/Ir abundance ratios are presented for nonmarine (Hell Creek, Montana; Frenchman River, Saskatchewan) and marine Cretaceous-Tertiary boundary sites (Brazos River, Texas; Beloc, Haiti; DSDP 577 and DSDP 596). The Ru/Ir ratio varies from 0.5 to 1 within 4000 km of Chicxulub and increases to 2-3 at paleodistances (65 Ma) of up to 12,000 km from the impact site. For CI chondrites, Ru/Ir = 1.5. A ballistic model of ejecta cloud cooling and expansion, which employs the available vapor-pressure versus temperature data for Ru and It, predicts qualitatively similar global variation in the Ru/Ir ratio but by only a factor of 1.5. We infer that several other factors, such as remobilization of PGE during diagenesis, preferential oxidation of Ru, condensation kinetics and atmospheric chemical and circulation processes, may account for the observed larger Ru/Ir variation.
    Schlagwort(e): 91-596; Calculated; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Glomar Challenger; Inductively coupled plasma - mass spectrometry (ICP-MS); Iridium; Leg91; Palladium; Platinum; Rubidium; Rubidium/Iridium ratio; Sample code/label; South Pacific
    Materialart: Dataset
    Format: text/tab-separated-values, 72 data points
    Standort Signatur Einschränkungen Verfügbarkeit
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    DATA PANGAEA
  • 2
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    Age constraints on faulting and fault reactivation: a multi-chronological approach (2018)
    Springer-Verlag | Berlin/Heidelberg
    Details
    Publikationsdatum: 2021-03-29
    Beschreibung: Movement within the Earth’s upper crust is commonly accommodated by faults or shear zones, ranging in scale from micro-displacements to regional tectonic lineaments. Since faults are active on different time scales and can be repeatedly reactivated, their displacement chronology is difficult to reconstruct. This study represents a multi-geochronological approach to unravel the evolution of an intracontinental fault zone locality along the Danube Fault, central Europe. At the investigated fault locality, ancient motion has produced a cataclastic deformation zone in which the cataclastic material was subjected to hydrothermal alteration and K-feldspar was almost completely replaced by illite and other phyllosilicates. Five different geochronological techniques (zircon Pb-evaporation, K–Ar and Rb–Sr illite, apatite fission track and fluorite (U-Th)/He) have been applied to explore the temporal fault activity. The upper time limit for initiation of faulting is constrained by the crystallization age of the primary rock type (known as “Kristallgranit”) at 325 ± 7 Ma, whereas the K–Ar and Rb–Sr ages of two illite fractions 〈2 μm (266–255 Ma) are interpreted to date fluid infiltration events during the final stage of the cataclastic deformation period. During this time, the “Kristallgranit” was already at or near the Earth’s surface as indicated by the sedimentary record and thermal modelling results of apatite fission track data. (U–Th)/He thermochronology of two single fluorite grains from a fluorite–quartz vein within the fault zone yield Cretaceous ages that clearly postdate their Late-Variscan mineralization age. We propose that later reactivation of the fault caused loss of helium in the fluorites. This assertion is supported by geological evidence, i.e. offsets of Jurassic and Cretaceous sediments along the fault and apatite fission track thermal modelling results are consistent with the prevalence of elevated temperatures (50–80°C) in the fault zone during the Cretaceous.
    Schlagwort(e): Argillic alteration; Fault zone; K–Ar illite; Apatite fission track; (U–Th)/He thermochronology ; 551 ; Earth Sciences; Geology ; Geophysics/Geodesy
    Sprache: Englisch
    Materialart: article , publishedVersion
    Format: application/pdf
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    CITATION GEO-LEO
  • 3
    Digitale Medien
    Digitale Medien
    GOLD, IRIDIUM, PALLADIUM AND PLATINUM IN REFERENCE STANDARD PCC-1 AND A KOMATIITIC PERIDOTITE: IMPLICATIONS FOR SELECTION OF IGNEOUS ROCK REFERENCE MATERIALS FOR PPB-LEVEL NOBLE METAL ANALYSIS (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 16 (1992), S. 0 
    Details
    ISSN: 1751-908X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie
    Notizen: New analyses for AU, Ir, Pd and Pt in the USGS rock standard PCC-1, carried out by two different radiochemical neutron activation procedures, are compared with similar analyses of a spinifex-textured komatiitic peridotite. Better precision obtained for most of these elements on the komatiitic peridotite, in conjunction with consideration of literature values for PCC-1, suggest that the volcanic peridotite is characterized by a more homogeneous distribution of noble metals than PCC-1, a plutonic peridotite. These results suggest that reference materials for the analysis of sulfur-poor mafic and ultramafie rocks with background levels of noble metals will be more satisfactory if volcanic rocks are selected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1751-908X.1992.tb00489.x
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    Artikel (Nationallizenzen)
    Volltext
  • 4
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    Gigantic eruption of a Carpathian volcano marks the largest Miocene transgression of Eastern Paratethys (2021)
    Elsevier
    Details
    Publikationsdatum: 2024-02-07
    Beschreibung: Highlights • Combined U-Pb and (U-Th)/He dating provides accurate eruption ages for the Gorelka tephra. • The largest marine transgression of the Eastern Paratethys in the Miocene was at ∼11.5 Ma. • VEI ∼7.4 eruption from a volcanic source in the Carpathians produced the Gorelka tephra. • Westerly winds transported the Gorelka tephra ∼1500 km ENE from the volcanic source. Volcanic ash layers (tephras) dispersed over large areas may offer important time markers in the geological record provided their age and geochemical fingerprint can be established. Accurately dated and geochemically characterized tephras are essential in correlation of temporally and spatially discontinuous geological records, which is key for paleoenvironmental, paleoclimatic, and paleogeographic reconstructions. Here we report geochronological and geochemical data for the Gorelka tephra (southwestern Russia) – a prominent tephra of uncertain age and origin that provides a key time marker for the largest marine transgression of the Eastern Paratethys Sea in the Miocene. Coupled U-Pb and (U-Th)/He dating of zircon crystals constrains the eruption age of the Gorelka tephra, and hence the age of the highest stand of Eastern Paratethys in the Miocene, to 11.5±0.5 Ma. Geochemical characteristics in combination with the new eruption age and tephra volume estimates suggest a magnitude ∼7.4 eruption from a volcanic source in the Transcarpathian region. The Gorelka tephra was transported ∼1,500 km ENE from its source by westerly winds, which were typical for the atmospheric circulation regime within the Ferrel cell in Central Europe during Sarmatian times. Based on the results presented here, the Gorelka tephra provides a reliable tie-point for paleoenvironmental and stratigraphic correlations across southeastern Europe.
    Materialart: Article , PeerReviewed
    Format: text
    Format: archive
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    OceanRep: Artikel in einer Fachzeitschrift - begutachtet
  • 5
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    Eo-Alpine metamorphism and the ‘mid-Miocene thermal event’ in the Western Carpathians (Slovakia): new evidence from multiple thermochronology (2012)
    Cambridge University Press
    Details
    Publikationsdatum: 2012-01-01
    Beschreibung: A combination of zircon (U–Th)/He (ZHe), apatite fission track (AFT) and apatite (U–Th)/He (AHe) dating methods is applied to constrain the metamorphic and exhumation history of the Tatric part of the Branisko Mountains in the Western Carpathians. ZHe ages from the basement samples prove the basement experienced a very low-grade to low-grade Eo-Alpine metamorphic overprint in mid-Cretaceous times. Miocene AFT and AHe ages found in the basement and in the Palaeogene sediments conclusively demonstrate that the Branisko Mts experienced a ‘mid-Miocene thermal event’. This thermal event had a regional character and was related to magmatic and/or burial heating that exposed the sediment and basement samples to ~ 120–130°C and ~ 100–190°C, respectively.
    Print ISSN: 0016-7568
    Digitale ISSN: 1469-5081
    Thema: Geologie und Paläontologie
    Publiziert von Cambridge University Press
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    PAPER CURRENT
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