The effect of slab gaps on subduction dynamics and mantle upwelling

Ágnes Király, Daniel E. Portner, Kirstie L. Haynie, Benjamin H. Chilson-Parks, Tithi Ghosh, Margarete Jadamec, Anna Makushkina, Michael Manga, Louis Moresi, Keely A. O'Farrell

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Gaps within a subducting plate can alter the surrounding mantle flow field and the overall subduction zone dynamics by allowing hot sub-slab mantle to flow through the gaps and into the mantle wedge. This through-slab flow can produce melting of the slab gap edges as well as significant upwelling that can lead to anomalous alkaline volcanism and/or dynamic uplift in the overriding plate, while the altered mantle flow patterns affect the trench evolution. Numerous geodynamic models have investigated the processes that form slab gaps, but few studies have examined the dynamics of slab gap-altered mantle flow, its effects on trench morphology and kinematics, or the controlling parameters on these processes. Here, laboratory subduction models with a pre-cut gap in a subducting silicone plate are used to explore how slab gap size, and slab gap depth influence the surrounding mantle flow field and trench dynamics. Results suggest that both the vertical extent and the depth of the top (trailing edge) of the slab gap are crucial parameters for modulating overall subduction dynamics. They show that a slab gap, which occurs near the surface and initially comprises 30% of the subducting plate width, can extend enough vertically in the slab to produce significant vertical flow through the gap. Changes to the trench geometry and kinematics are also evident in the models, such that double- and triple-arc geometries are formed during subduction of a shallow slab gap. All of these results are consistent with observations of slab gaps and their induced surface expressions, or the lack thereof, in Eastern Anatolia, East Java, Italy, and Argentina.

Original languageEnglish
Article number228458
JournalTectonophysics
Volume785
DOIs
StatePublished - Jun 20 2020

Bibliographical note

Funding Information:
The authors are grateful for editor K. Wang, as well as A. Replumaz, S. Cruden and the anonymous reviewer for their useful suggestions, which helped to improve the paper. The laboratory experiments were performed in the Laboratory of Experimental Tectonics at the University of Roma Tre. The Grant to Department of Science, Roma Tre University (MIUR-Italy Dipartimenti di Eccellenza, ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016 ) is gratefully acknowledged. This project and collaboration were initiated during the 2017 CIDER program, hosted at the University of California, Berkeley (National Science Foundation award EAR-1135452 ). A. K. was supported by the Research Council of Norway Centres of Excellence project 223272 . Further data about the models can be found in the Supplementary materials.

Funding Information:
The authors are grateful for editor K. Wang, as well as A. Replumaz, S. Cruden and the anonymous reviewer for their useful suggestions, which helped to improve the paper. The laboratory experiments were performed in the Laboratory of Experimental Tectonics at the University of Roma Tre. The Grant to Department of Science, Roma Tre University (MIUR-Italy Dipartimenti di Eccellenza, ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016) is gratefully acknowledged. This project and collaboration were initiated during the 2017 CIDER program, hosted at the University of California, Berkeley (National Science Foundation award EAR-1135452). A. K. was supported by the Research Council of Norway Centres of Excellence project 223272. Further data about the models can be found in the Supplementary materials.

Publisher Copyright:
© 2020

Keywords

  • Analog modeling
  • Mantle flow
  • PIV
  • Slab gap
  • Subduction dynamics

ASJC Scopus subject areas

  • Geophysics
  • Earth-Surface Processes

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