Mao, Xiaolin and Gurnis, Michael and May, Dave A. (2017) Subduction initiation with vertical lithospheric heterogeneities and new fault formation. Geophysical Research Letters, 44 (22). pp. 11349-11356. ISSN 0094-8276. doi:10.1002/2017GL075389. https://resolver.caltech.edu/CaltechAUTHORS:20171030-143556755
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Abstract
How subduction initiates with mechanically unfavorable lithospheric heterogeneities is important and rarely studied. We investigate this with a geodynamic model for the Puysegur Incipient Subduction Zone (PISZ) south of New Zealand. The model incorporates a true free surface, elasto-visco-plastic rheology and phase changes. Our predictions fit the morphology of the Puysegur Trench and Ridge and the deformation history on the overriding plate. We show how a new thrust fault forms and evolves into a smooth subduction interface, and how a preexisting weak zone can become a vertical fault inboard of the thrust fault during subduction initiation, consistent with two-fault system at PISZ. The model suggests that the PISZ may not yet be self-sustaining. We propose that the Snares Zone (or Snares Trough) is caused by plate coupling differences between shallower and deeper parts, the tectonic sliver between two faults experiences strong rotation, and low-density material accumulates beneath the Snares Zone.
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Additional Information: | © 2017 American Geophysical Union. Received 22 AUG 2017; Accepted 24 OCT 2017; Accepted article online 30 OCT 2017; Published online 20 NOV 2017. X. M. and M. G. were supported by the National Science Foundation through awards EAR-1247022, EAR-1645775, and OCE-1654766. D. A. M. acknowledges financial support from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement 279925. Computations carried out on the NSF XSEDE systems, made possible by TG-EAR160027. We thank Magali Billen for her detailed review and constructive suggestions. Additional information for this article can be found in the supporting information. Source data for Figures 3 and 4 are available at https://doi.org/10.22002/D1.298. | ||||||||||||
Group: | Seismological Laboratory | ||||||||||||
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Subject Keywords: | subduction initiation; fault formation; phase change; force balance; subduction zone; surface process | ||||||||||||
Issue or Number: | 22 | ||||||||||||
DOI: | 10.1002/2017GL075389 | ||||||||||||
Record Number: | CaltechAUTHORS:20171030-143556755 | ||||||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20171030-143556755 | ||||||||||||
Official Citation: | Mao, X., Gurnis, M., & May, D. A. (2017). Subduction initiation with vertical lithospheric heterogeneities and new fault formation. Geophysical Research Letters, 44, 11,349–11,356. https://doi.org/10.1002/2017GL075389 | ||||||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||
ID Code: | 82786 | ||||||||||||
Collection: | CaltechAUTHORS | ||||||||||||
Deposited By: | Tony Diaz | ||||||||||||
Deposited On: | 30 Oct 2017 21:47 | ||||||||||||
Last Modified: | 15 Nov 2021 19:53 |
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