EGU2020-5076
https://doi.org/10.5194/egusphere-egu2020-5076
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Indo-Atlantic plate accelerations and tectonic reorganisations in the Late Cretaceous: no need for plume-push forces

Lucia Perez-Diaz1, Graeme Eagles2, and Karin Sigloch1
Lucia Perez-Diaz et al.
  • 1University of Oxford, Earth Sciences, Oxford, UK
  • 2Alfred Wegener Institute, Bremerhaven, Germany

Observations of the apparent links between plate speeds and the global distribution of plate boundary types have led to the suggestion that subduction may provide the largest component in the balance of torques maintaining plate motions. This would imply that plate speeds should not exceed the sinking rates of slabs into the upper mantle. Instances of this ‘speed limit’ having been broken may thus hint at the existence of driving mechanisms additional to those resulting from plate boundary forces. The arrival and emplacement of the Deccan-Réunion mantle plume beneath the Indian-African plate boundary in the 67-62 Ma period has been discussed in terms of one such additional driving mechanism. Its spatial and temporal coincidence with an abrupt speed-up of the Indian plate has led to suggestions that the arrival of plumes at the base of the lithosphere can introduce a push force capable of overwhelming entire circuits of plates and triggering plate tectonic reorganizations.

 

We challenge the occurrence of a pulse of anticorrelating accelerations and decelerations in seafloor spreading rates around the African and Indian plates and, with it, the proposal that plume-related forces in the Indian Ocean had a significant impact on the Indo-Atlantic plate circuit in late Cretaceous and Paleogene times. Using existing and newly-calculated high-resolution models of plate motion based on seafloor spreading data, we show that the increase in divergence rates previously documented for ridges bordering the Indian plate is artefactual. Records from spreading centers throughout the Indo-Atlantic plate circuit show an ubiquitous increase in plate divergence rates at 67-64 Ma, which is best explained in terms of a timescale error affecting chrons 29-28. Corrected for this error, the motion of the circuit’s plates show little change around Deccan times. Furthermore, we find that Post-Deccan reorganization of the Indo-Atlantic plate circuit can be explained in terms of long-term plate boundary evolution without the need to invoke a large additional plume push force in the 70-60 Ma period.

How to cite: Perez-Diaz, L., Eagles, G., and Sigloch, K.: Indo-Atlantic plate accelerations and tectonic reorganisations in the Late Cretaceous: no need for plume-push forces, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5076, https://doi.org/10.5194/egusphere-egu2020-5076, 2020

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Display material version 2 – uploaded on 07 May 2020
Small change made in response to comment by Bernhard Steinberger
Display material version 1 – uploaded on 03 May 2020
  • CC1: Comment on EGU2020-5076, Christoph Grützner, 04 May 2020

    Very cool story. Do you have any idea on what kind of timescale error this could be - what possibly went wrong and how can it be avoided in the future? Thanks!

  • AC1: Comment on EGU2020-5076, Lucia Perez-Diaz, 05 May 2020

    Thanks! Our hope is that by identifying a possible error, this study (like many before it) will lead to a reassessment of the timescale. We intend to roughly estimate the magnitude of the error but fine-tuning the timescale will probably require a global reassessment of magnetic reversal isochron spacings and dated onshore paleomagnetic intensity records - no small task!

  • CC2: Comment on EGU2020-5076, Christoph Grützner, 05 May 2020

    Thanks a lot - huge task indeed. I am curious to see what other problems a revised timesclae will affect.

  • CC3: Comment on EGU2020-5076, Bernhard Steinberger, 07 May 2020

    Note that in Van Hinsbergen et al. (2011) we write "The 65–50 Ma convergence rate increase, however, is larger than can be explained by plume head spreading alone." So that basically agrees with your story, but readers of your poster may wrongly assume that you contradict us here. 

    • AC2: Reply to CC3, Lucia Perez-Diaz, 07 May 2020

      You are absolutely right Bernhard, i'm sorry about this - in "simplifying" things I overlooked that detail. I will re-upload a corrected version. Thanks for pointing it out to me!