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ORIGINAL RESEARCH article

Front. Earth Sci.
Sec. Geochemistry
Volume 12 - 2024 | doi: 10.3389/feart.2024.1456429

Plume-influenced mid-ocean ridges -Insights into the geodynamics from the Foundation Segment on the Pacific-Antarctic Ridge

Provisionally accepted
Philipp A. Brandl Philipp A. Brandl 1*Christoph Beier Christoph Beier 2Karsten M. Haase Karsten M. Haase 3Felix Genske Felix Genske 4Folkmar Hauff Folkmar Hauff 1Marcel Regelous Marcel Regelous 3Colin Devey Colin Devey 1Lars H. Rüpke Lars H. Rüpke 1
  • 1 GEOMAR Helmholtz Center for Ocean Research Kiel, Helmholtz Association of German Research Centres (HZ), Kiel, Germany
  • 2 Department of Geosciences and Geography, University of Helsinki, Helsinki, Uusimaa, Finland
  • 3 GeoZentrum Nordbayern, Department Geographie und Geowissenschaften, Fakultät für Naturwissenschaften, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Bavaria, Germany
  • 4 Institut für Mineralogie, University of Münster, Münster, North Rhine-Westphalia, Germany

The final, formatted version of the article will be published soon.

    The intersection of the Foundation Plume with the Pacific-Antarctic Ridge is a key location in global geodynamics where a mantle plume is approached by and interacting with a fast-spreading mid-ocean ridge. Here, we discuss a comprehensive major and trace element and Sr-Nd-Pb isotope dataset of new and existing samples from the young Foundation Seamount Chain (<5 Ma) and adjacent section of the Pacific-Antarctic Ridge. We use the geochemistry of axial, off-axis and intraplate lavas to map the spatial extent of plume dispersal underneath the ridge as well as the internal zonation of the upwelling plume. We show that the unusual length, increased crustal thickness and occurrence of silicic rocks on the axis of the Foundation Segment are the direct result of plume being tapped by the axial melting zone. We demonstrate that the plume is not homogeneous but shows a HIMU-like (high time-integrated 238 U/ 204 Pb) OIB (Ocean Island Basalt) component characterized by 206 Pb/ 204 Pb of up to 20.5 in its center and a more EM1-like (Enriched Mantle one) OIB component characterized by low U/Pb and 206 Pb/ 204 Pb but high Rb/Nb and 87 Sr/ 86 Sr towards its edges. Plume entrainment leads to a high magma supply rate that fosters the formation of silicic rocks and triggers the lengthening of the segment over time. However, plume dispersal is not symmetric as the geochemical tracers for the OIB component are extending <100 km northwards but >300 km southwards. We relate this to the current plate tectonic framework in which the obliquity between the migrating ridge and the absolute plate motions induces a sub-axial asthenospheric flow that preferentially channels plume material southwards.

    Keywords: Foundation, Pacific-Antarctic Ridge, Plume-ridge interaction, Ridge segmentation, Intraplate, Mid-ocean ridge, geochemistry

    Received: 28 Jun 2024; Accepted: 26 Aug 2024.

    Copyright: © 2024 Brandl, Beier, Haase, Genske, Hauff, Regelous, Devey and Rüpke. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Philipp A. Brandl, GEOMAR Helmholtz Center for Ocean Research Kiel, Helmholtz Association of German Research Centres (HZ), Kiel, Germany

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