GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Document type
Publisher
Language
Years
  • 1
    Online Resource
    Online Resource
    Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records (2008)
    Associated volumes
    Details Availability
    In: Earth and planetary science letters, Amsterdam [u.a.] : Elsevier, 1966, 273(2008), 1/2, Seite 175-183, 1385-013X
    In: volume:273
    In: year:2008
    In: number:1/2
    In: pages:175-183
    Description / Table of Contents: Three ferromanganese crusts from the northeast, northwest and central Atlantic were re-dated using osmium (Os) isotope stratigraphy and yield ages from middle Miocene to the present. The three Os isotope records do not show evidence for growth hiatuses. The reconstructed Os isotope-based growth rates for the sections older than 10 Ma are higher than those determined previously by the combined beryllium isotope (10Be/9Be) and cobalt (Co) constant-flux methods, which results in a decrease in the maximum age of each crust. This re-dating does not lead to significant changes to the interpretation of previously determined radiogenic isotope neodymium, lead (Nd, Pb) time series because the variability of these isotopes was very small in the records of the three crusts prior to 10 Ma. The Os isotope record of the central Atlantic crust shows a pronounced minimum during the middle Miocene between 15 and 12 Ma, similar to a minimum previously observed in two ferromanganese crusts from the central Pacific. For the other two Atlantic crusts, the Os isotope records and their calibration to the global seawater curve for the middle Miocene are either more uncertain or too short and thus do not allow for a reliable identification of an isotopic minimum. Similar to pronounced minima reported previously for the Cretaceous/Tertiary and Eocene/Oligocene boundaries, possible interpretations for the newly identified middle Miocene Os isotope minimum include changes in weathering intensity and/or a meteorite impact coinciding with the formation of the Nördlinger Ries Crater. It is suggested that the eruption and weathering of the Columbia River flood basalts provided a significant amount of the unradiogenic Os required to produce the middle Miocene minimum.
    Type of Medium: Online Resource
    Pages: graph. Darst
    ISSN: 1385-013X
    DOI: 0.1016/j.epsl.2008.06.028
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 2
    Article
    Article
    Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments (2007)
    Associated volumes
    Details Availability
    In: Chemical geology, Amsterdam [u.a.] : Elsevier, 1966, 242(2007), Seite 351-370, 0009-2541
    In: volume:242
    In: year:2007
    In: pages:351-370
    Type of Medium: Article
    Pages: Graph. Darst.
    ISSN: 0009-2541
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 3
    Article
    Article
    Cenozoic changes in atmospheric lead recorded in central Pacific ferromanganese crusts (2006)
    Associated volumes
    Details Availability
    In: Earth & planetary science letters, Amsterdam [u.a.] : Elsevier, 1966, 253(2007), Seite 57-66, 0012-821X
    In: volume:253
    In: year:2007
    In: pages:57-66
    Description / Table of Contents: The possible sources of pre-anthropogenic Pb contributed to the world's oceans have been the focus of considerable study. The role of eolian dust versus riverine inputs has been of particular interest. With better calibration of isotopic records from central Pacific ferromanganese crusts using Os isotope stratigraphy it now appears that deep water Pb isotopic compositions were effectively homogeneous over a distance of 5000 km for the past 80 Myr. The composition shifted slightly from high 206Pb/204Pb ratios in the range of 18.87±0.02 before 65 Ma to lower values of 18.62±0.02 by 45 Ma and then gradually increased again very slightly to the present day ratio of 18.67±0.02. The regional homogeneity provides evidence of a dominant well-mixed atmospheric source the most likely candidate for which is volcanic aerosols contributed either directly or as soluble condensates on eolian dust. The slight shift in Pb isotope composition of deep waters in the central Pacific between 65 and 45 Ma may be the result of a regional- or perhaps global-scale change in the sources of volcanic exhalations and volcanic activity caused by an increase in the importance of melting and assimilation of older continental crustal components over the Cenozoic.
    Type of Medium: Article
    ISSN: 0012-821X
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GEOMAR CATALOGUE
    Link to Library Catalog
    get availability status
  • 4
    facet.materialart.
    Unknown
    Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments (2007)
    Elsevier
    In:  Chemical Geology, 242 . pp. 351-370.
    Details
    Publication Date: 2017-12-11
    Description: The extraction of a deepwater radiogenic isotope signal from marine sediments is a powerful, though under-exploited, tool for the characterisation of past climates and modes of ocean circulation. The radiogenic and radioactive isotope compositions (Nd, Pb, Th) of ambient deepwater are stored in authigenic Fe–Mn oxyhydroxide coatings in marine sediments, but the unambiguous separation of the isotopic signal in this phase from other sedimentary components is difficult and measures are needed to ensure its seawater origin. Here the extracted Fe–Mn oxyhydroxide phase is investigated geochemically and isotopically in order to constrain the potential and the limitations of the reconstruction of deepwater radiogenic isotope compositions from marine sediments. Our results show that the isotope compositions of elements such as Sr and Os obtained from the Fe–Mn oxyhydroxide fraction are easily disturbed by detrital contributions originating from the extraction process, whereas the seawater isotope compositions of Nd, Pb and Th can be reliably extracted from marine sediments in the North Atlantic. The main reason is that the Nd, Pb and Th concentrations in the detrital phase of pelagic sediments are much lower than in the Fe–Mn oxyhydroxide fractions. This is reflected in Al/Nd, Al/Pb and Al/Th ratios of the Fe–Mn oxyhydroxide fractions, which are as low as or even lower than those of hydrogenetic ferromanganese crusts. Mass balance calculations illustrate that the use of the 87Sr/86Sr isotope composition to confirm the seawater origin of the extracted Nd, Pb and Th isotope signals is misleading. Even though the 87Sr/86Sr in the Fe–Mn oxyhydroxide fractions is often higher than the seawater Sr isotope composition, the corresponding detrital contribution does not translate into altered seawater Nd, Pb and Th isotope compositions due to mass balance constraints. Overall the rare earth element patterns, elemental ratios, as well as the mass balance calculations presented here highlight the potential of using authigenic Fe–Mn oxyhydroxide coatings as paleoceanographic archives for the analysis of past seawater Nd, Pb and Th isotope compositions.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.chemgeo.2007.03.021
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
    facet.materialart.
    Unknown
    Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records (2008)
    Elsevier
    In:  Earth and Planetary Science Letters, 273 . pp. 175-187.
    Details
    Publication Date: 2017-02-09
    Description: Three ferromanganese crusts from the northeast, northwest and central Atlantic were re-dated using osmium (Os) isotope stratigraphy and yield ages from middle Miocene to the present. The three Os isotope records do not show evidence for growth hiatuses. The reconstructed Os isotope-based growth rates for the sections older than 10 Ma are higher than those determined previously by the combined beryllium isotope (10Be/9Be) and cobalt (Co) constant-flux methods, which results in a decrease in the maximum age of each crust. This re-dating does not lead to significant changes to the interpretation of previously determined radiogenic isotope neodymium, lead (Nd, Pb) time series because the variability of these isotopes was very small in the records of the three crusts prior to 10 Ma. The Os isotope record of the central Atlantic crust shows a pronounced minimum during the middle Miocene between 15 and 12 Ma, similar to a minimum previously observed in two ferromanganese crusts from the central Pacific. For the other two Atlantic crusts, the Os isotope records and their calibration to the global seawater curve for the middle Miocene are either more uncertain or too short and thus do not allow for a reliable identification of an isotopic minimum. Similar to pronounced minima reported previously for the Cretaceous/Tertiary and Eocene/Oligocene boundaries, possible interpretations for the newly identified middle Miocene Os isotope minimum include changes in weathering intensity and/or a meteorite impact coinciding with the formation of the Nördlinger Ries Crater. It is suggested that the eruption and weathering of the Columbia River flood basalts provided a significant amount of the unradiogenic Os required to produce the middle Miocene minimum.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2008.06.028
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    OceanRep: Article in a Scientific Journal - peer-reviewed
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...