Horizontal mantle flow controls subduction dynamics.
- Ficini E Department of Earth Sciences, Sapienza University of Rome, Rome, Italy. eleonora.ficini@uniroma1.it.
- Dal Zilio L Institute of Geophysics, ETH Zurich, Zürich, Switzerland.
- Doglioni C Department of Earth Sciences, Sapienza University of Rome, Rome, Italy.
- Gerya TV Institute of Geophysics, ETH Zurich, Zürich, Switzerland.
- 2017-08-10
Published in:
- Scientific reports. - 2017
English
It is generally accepted that subduction is driven by downgoing-plate negative buoyancy. Yet plate age -the main control on buoyancy- exhibits little correlation with most of the present-day subduction velocities and slab dips. "West"-directed subduction zones are on average steeper (~65°) than "East"-directed (~27°). Also, a "westerly"-directed net rotation of the lithosphere relative to the mantle has been detected in the hotspot reference frame. Thus, the existence of an "easterly"-directed horizontal mantle wind could explain this subduction asymmetry, favouring steepening or lifting of slab dip angles. Here we test this hypothesis using high-resolution two-dimensional numerical thermomechanical models of oceanic plate subduction interacting with a mantle flow. Results show that when subduction polarity is opposite to that of the mantle flow, the descending slab dips subvertically and the hinge retreats, thus leading to the development of a back-arc basin. In contrast, concordance between mantle flow and subduction polarity results in shallow dipping subduction, hinge advance and pronounced topography of the overriding plate, regardless of their age-dependent negative buoyancy. Our results are consistent with seismicity data and tomographic images of subduction zones. Thus, our models may explain why subduction asymmetry is a common feature of convergent margins on Earth.
- Language
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- English
- Open access status
- gold
- Identifiers
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- DOI 10.1038/s41598-017-06551-y
- PMID 28790325
- Persistent URL
- https://sonar.ch/global/documents/277172
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