Overriding Plate Deformation and Topography During Slab Rollback and Slab Rollover: Insights From Subduction Experiments

K. Xue*, W. P. Schellart, V. Strak

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Some subduction zones in nature show mainly overriding plate (OP) extension and low topography, and others show mainly shortening and elevated topography. Here we investigate how end-member subduction modes (trench retreat with slab rollback and trench advance with slab rollover) affect overriding plate deformation (OPD), topography, and mantle flow with time-evolving three-dimensional fully-dynamic analog models using particle image velocimetry. We conduct two sets of experiments, one of which is characterized by trench retreat, and the other characterized by trench advance. Experiments showing continuous trench retreat experience overall OP extension, while experiments dominated by trench advance experience overall shortening. Both subduction modes present fore-arc shortening and intra-arc extension. Our experiments indicate that the overall OPD is mainly driven by the horizontal mantle flow at the base of the OP inducing a viscous drag force (FD), and is determined by the horizontal gradient of the horizontal mantle shear rate (Formula presented.), which controls the horizontal trench-normal gradient in FD. Furthermore, a large-scale trenchward OP tilting and overall subsidence are observed in the experiments showing continuous trench retreat, while a landward OP tilting and an overall uplift are observed during long-term trench advance. The two types of topography during the two different subduction modes can be ascribed to the downward component of the large-scale trenchward mantle flow and the upward component of the landward mantle flow, respectively, and thus represent forms of dynamic topography. Our models showing trench advance provide a possible mechanism for OPD and topography at the Makran subduction zone.

Original languageEnglish
Article numbere2021TC007089
Pages (from-to)1-19
Number of pages19
JournalTectonics
Volume41
Issue number2
Early online date26 Jan 2022
DOIs
Publication statusPublished - Feb 2022

Bibliographical note

Funding Information:
We would like to thank reviewer Adam Beall and two anonymous reviewers for their constructive comments that have improved the contents of the paper. This research has been funded by a Vici grant (016. VICI.170.110) from the Dutch National Science Foundation (NWO) awarded to W. P. Schellart. We acknowledge the use of a Lavision stereoscopic PIV equipment and software for visualization.

Publisher Copyright:
© Wiley Periodicals LLC. The Authors.

Keywords

  • mantle flow
  • overriding plate deformation
  • subduction
  • topography
  • trench migration

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