Plume–ridge interactions: ridgeward versus plate-drag plume flow
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Published:2023-03-20
Issue:3
Volume:14
Page:353-368
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ISSN:1869-9529
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Container-title:Solid Earth
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language:en
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Short-container-title:Solid Earth
Author:
Pang Fengping, Liao Jie, Ballmer Maxim D.ORCID, Li Lun
Abstract
Abstract. The analysis of mid-ocean ridges and hotspots that are sourced by
deep-rooted mantle plumes allows us to get a glimpse of mantle structure and
dynamics. Dynamical interaction between ridge and plume processes have been
widely proposed and studied, particularly in terms of ridgeward plume flow.
However, the effects of plate drag on plume–lithosphere and plume–ridge
interaction remain poorly understood. In particular, the mechanisms that
control plume flow towards vs. away from the ridge have not yet been
systematically studied. Here, we use 2D thermomechanical numerical models of
plume–ridge interaction to systematically explore the effects of (i) ridge-spreading rate, (ii) initial plume head radius and (iii) plume–ridge
distance. Our numerical experiments suggest two different geodynamic
regimes: (1) plume flow towards the ridge is favored by strong buoyant
mantle plumes, slow spreading rates and small plume–ridge distances; (2) plume drag away from the ridge is in turn promoted by fast ridge spreading
for small-to-intermediate plumes and large plume–ridge distances. We find
that the pressure gradient between the buoyant plume and spreading ridge at
first drives ridgeward flow, but eventually the competition between plate
drag and the gravitational force of plume flow along the base of the sloping
lithosphere controls the fate of plume (spreading towards vs. away from the
ridge). Our results highlight that fast-spreading ridges exert strong plate-dragging force, which sheds new light on natural observations of largely
absent plume–lithosphere interaction along fast-spreading ridges, such as
the East Pacific Rise.
Funder
National Natural Science Foundation of China
Publisher
Copernicus GmbH
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