Post-subduction tectonics induced by extension from a lithospheric drip

Simone Pilia* (Corresponding Author), D. R. Davies , R. Hall, C. Bacon, Amy Gilligan, Tim Greenfield, Felix Tongkul, S.C. Kramer , C. R Wilson , S Ghelichkhan , Dave Cornwell, L. Colli, N. Rawlinson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Subduction termination leads to complex tectonic and geological activity, with the observational record often including clear evidence for exhumation, anomalous magmatism and topographic subsidence, followed by rapid uplift. However, the mechanism(s) driving these responses remain enigmatic and cannot be reconciled with our current understanding of post-subduction tectonics. A prime example of recent subduction termination can be found in northern Borneo (Malaysia), where subduction ceased in the late Miocene (at ~9 Ma). Here, we use recently acquired passive-seismic data to image, at unprecedented resolution (~35 km), a sub-vertical lithospheric drip, inferred to have developed as a Rayleigh-Taylor gravitational instability from the root of a volcanic arc. We use thermo-mechanical simulations to reconcile these images with timedependent dynamical processes within the crust and underlying mantle following
subduction termination. Our model predictions illustrate how significant extension from a lithospheric drip can thin the crust in an adjacent orogenic belt, facilitating lower crustal melting and possible exhumation of subcontinental material, as is observed. These discoveries provide evidence for extension-driven melting of the lower crust, exhumation, core-complex formation, and orogeny that may also occur in other areas of recent subduction termination.
Original languageEnglish
Pages (from-to)646-652
Number of pages7
JournalNature Geoscience
Volume16
Early online date19 Jun 2023
DOIs
Publication statusPublished - Jul 2023

Bibliographical note

Acknowledgements
S.P. acknowledges support from the Natural Environmental Research Council (NERC) Grant NE/R013500/1 and from the European Union’s Horizon 2020 Research and Innovation Program under Marie Skłodowska-Curie Grant Agreement 790203. We thank the TanDEM-X Science Communication Team (German Aerospace Center (DLR) e.V.) for providing TanDEM topographic data. We thank the NERC Geophysical Equipment Facility for loan 1038. Numerical simulations were undertaken on the NCI National Facility in Canberra, Australia, which is supported by the Australian Commonwealth Government. A.G. was funded by an Independent Research Fellowship from the Royal Astronomical Society.

Data Availability Statement

Data availability
Part of the nBOSS dataset is accessible through the IRIS Data Management (https://www.fdsn.org/networks/detail/YC_2018/). Data from the remaining nBOSS stations will be available from February 2024. Data from the Malaysian national seismic network (https://www.fdsn.org/networks/detail/MY/) are restricted but may be obtained by contacting the Malaysian Meteorological Department.

Code availability
The Fluidity computational modelling framework, including source code and documentation, is available from https://fluidityproject.github.io/; the latest release, which was used for the simulations presented herein, has been archived at Zenodo: https://doi.org/10.5281/zenodo.5221157. The source code and manual for FMTOMO are available via http://iearth.edu.au/codes/FMTOMO/.

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