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  • Nature Research  (2)
  • The University of Chicago Press  (1)
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  • 1
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    A Revised 87Sr/86Sr Curve for the Silurian: Implications for Global Ocean Chemistry and the Silurian Timescale (2011)
    The University of Chicago Press
    In:  The Journal of Geology, 119 (4). pp. 335-349.
    Details
    Publication Date: 2019-01-22
    Description: Recent recalibration of the Silurian timescale and improved global chronostratigraphic correlation of Silurian strata significantly altered the Silurian (87)Sr/(86)Sr curve and the temporal extent of available data. Whereas previous Silurian (87)Sr/(86)Sr composites showed a generally monotonic increase throughout the Silurian, revisions to the Silurian timescale now require a major increase in the rate of change in (87)Sr/(86)Sr at or near the onset of the Gorstian Age of the Ludlow Epoch. Similarly, improved chronostratigraphic correlations between Silurian outcrops on Anticosti Island, Canada, and Gotland, Sweden, indicate that the middle part of the Telychian Age, which is roughly 10%-15% of the total duration of the Silurian period, is undersampled and underrepresented in Silurian (87)Sr/(86)Sr composites. A revised Silurian (87)Sr/(86)Sr curve based on 241 new and published analyses confirms the significant increase in the rate of change of (87)Sr/(86)Sr toward more radiogenic values near the base of the Ludlow Series. On the basis of these data, we propose that the rapid trend toward more radiogenic (87)Sr/(86)Sr values is indicative of increased weathering of old sialic crust exposed during the Silurian uplift of portions of Baltica, Laurentia, and Avalonia. Importantly, however, the actual rate of change of (87)Sr/(86)Sr will remain equivocal until the durations of Silurian epochs and ages are better constrained.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1086/660117
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Evidence for compositionally distinct upper mantle plumelets since the early history of the Tristan-Gough hotspot (2023)
    Nature Research
    Details
    Publication Date: 2024-02-07
    Description: Recent studies indicate that mantle plumes, which transfer material and heat from the earth’s interior to its surface, represent multifaceted upwellings. The Tristan-Gough hotspot track (South Atlantic), which formed above a mantle plume, documents spatial geochemical zonation in two distinct sub-tracks since ~70 Ma. The origin and the sudden appearance of two distinct geochemical flavors is enigmatic, but could provide insights into the structural evolution of mantle plumes. Sr–Nd–Pb–Hf isotope data from the Late Cretaceous Rio Grande Rise and adjacent Jean Charcot Seamount Chain (South American Plate), which represent the counterpart of the older Tristan-Gough volcanic track (African Plate), extends the bilateral-zonation to ~100 Ma. Our results support recent numerical models, demonstrating that mantle plumes can split into distinct upper mantle conduits, and provide evidence that these plumelets formed at the plume head-to-plume tail transition. We attribute the plume zonation to sampling the geochemically-graded margin of the African Large Low-Shear-Velocity Province.
    Type: Article , PeerReviewed
    Format: text
    Format: other
    Format: other
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Mantle plume and rift-related volcanism during the evolution of the Rio Grande Rise (2022)
    Nature Research
    Details
    Publication Date: 2024-02-07
    Description: The Rio Grande Rise in the western South Atlantic Ocean has been interpreted as either an oceanic plateau related to the Tristan-Gough mantle plume, or a fragment of detached continental crust. Here we present new major and trace element data for volcanic rocks from the western and eastern Rio Grande Rise and the adjacent Jean Charcot Seamount Chain. The eastern Rio Grande Rise and older parts of the western Rio Grande Rise are comprised of tholeiitic basalt with moderately enriched trace element compositions and likely formed above the Tristan-Gough mantle plume close to the southern Mid-Atlantic Ridge. Younger alkalic lavas from the western Rio Grande Rise and the Jean Charcot Seamount Chain were formed by lower degrees of melting beneath thicker lithosphere in an intraplate setting possibly during rifting of the plateau. There is no clear geochemical evidence that remnants of continental crust are present beneath the Rio Grande Rise.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    Format: text
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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