• Dra.Lucía Pérez-Díaz, University of Oxford | Neftex (Halliburton)
• 17 November 2020; 12:00 h CET
• Online
• To join the seminar click here
• Further information:Dr. Juan Alcalde

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Abstract

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, leading to the establishment of “plume-push” hypothesis, which in recent years has gained significant traction.

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, we show that the previously documented increase in divergence rates around the Indian Ocean 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.

About the speaker

Lucia Perez-Diaz studied Geology at the University of Oviedo (Spain) and completed a PhD in Geodynamics at Royal Holloway (University of London) for which she received the GA’s Halstead Award (2018). Since completion of her doctorate she has held postdoctoral research positions at Royal Holloway and the University of Oxford, where her research has focused on improving understanding of the feedbacks between mantle dynamics, plate-scale processes and surface observations. She has recently joined Neftex (Halliburton) as a senior geodynamics specialist. Her current work focuses on the development of quantitative plate reconstruction techniques and the study of the dynamics of plate motion (from driving forces to intraplate stress). Lucia is the vice-president of the Geologists’ Association and one of the editors of the EGU’s Geodynamics Division blog.