Shuck, Brandon and Van Avendonk, Harm and Gulick, Sean P. S. and Gurnis, Michael and Sutherland, Rupert and Stock, Joann and Patel, Jiten and Hightower, Erin and Saustrup, Steffen and Hess, Thomas (2020) Strike-slip Enables Subduction Initiation beneath a Failed Rift: New Seismic Constraints from Puysegur Margin, New Zealand. . (Unpublished) https://resolver.caltech.edu/CaltechAUTHORS:20201023-130721209
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Abstract
Subduction initiation often takes advantage of previously weakened lithosphere and may preferentially nucleate along pre-existing plate boundaries. To evaluate how past tectonic regimes and inherited lithospheric structure might lead to self-sustaining subduction, we present an analysis of the Puysegur Trench, a young subduction zone with a rapidly evolving tectonic history. The Puysegur margin, south of New Zealand, has experienced a transformation from rifting to seafloor spreading to strike-slip, and most recently to incipient subduction, all in the last ~45 million years. Here we present deep-penetrating multichannel reflection (MCS) and ocean-bottom seismometer (OBS) tomographic images to document crustal structures along the margin. Our images reveal that the overriding Pacific Plate beneath the Solander Basin contains stretched continental crust with magmatic intrusions, which formed from Eocene-Oligocene rifting between the Campbell and Challenger plateaus. Rifting was more advanced to the south, yet never proceeded to breakup and seafloor spreading in the Solander Basin as previously thought. Subsequent strike-slip deformation translated continental crust northward causing an oblique collisional zone, with trailing ~10 Myr old oceanic lithosphere. Incipient subduction transpired as oceanic lithosphere from the south forcibly underthrust the continent-collision zone. We suggest that subduction initiation at the Puysegur Trench was assisted by inherited buoyancy contrasts and structural weaknesses that were imprinted into the lithosphere during earlier phases of continental rifting and strike-slip along the plate boundary. The Puysegur margin demonstrates that forced nucleation along a strike-slip boundary is a viable subduction initiation scenario and should be considered throughout Earth's history.
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Additional Information: | Published Online: Thu, 23 Jul 2020. We thank the captain, crew, and science party of the R/V Marcus Langseth for their efforts during the South Island Subduction Initiation Experiment. Thank you to Kelly Olsen, Andrew Gase, Justin Estep, and Dominik Kardell for guidance in seismic processing and invaluable feedback on seismic interpretations. Special thanks to the University of Texas Institute for Geophysics (UTIG) Marine Geology and Geophysics group for fruitful discussions which significantly improved this work. We are grateful to Mark Wiederspahn for his technical support and assistance with computational resources, and Marcy Davis and Dan Duncan for helping with multibeam and backscatter data gridding and visualization. The authors wish to acknowledge and thank the Paradigm University Grant Program of Emerson E&P Software for the use of Paradigm Echos for data processing in this project. The authors also wish to thank the Halliburton/Landmark University Grant program for the use of Decision Space Desktop and GeoProbe software used in the interpretation of this data. We thank IHS-Markit for a university educational license for Kingdom software, provided to Caltech, for seismic data visualization and interpretation. Research in this manuscript was supported by the National Science Foundation through awards OCE-1654689 (UT Austin) and OCE-1654766 (Caltech). Uninterpreted and interpreted seismic images shown in this study can be found in the supporting information. Underway geophysical data from MGL1803 are available from the Rolling Deck Repository (http://doi.org/10.7284/907966). Raw and processed seismic data used in this study are available through the Marine Geoscience Data System (http://doi.org/10.1594/IEDA/324659/). This is UTIG Contribution #XXXX. | ||||||||||||||||||
Group: | Seismological Laboratory | ||||||||||||||||||
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Record Number: | CaltechAUTHORS:20201023-130721209 | ||||||||||||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20201023-130721209 | ||||||||||||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||||||||
ID Code: | 106262 | ||||||||||||||||||
Collection: | CaltechAUTHORS | ||||||||||||||||||
Deposited By: | Tony Diaz | ||||||||||||||||||
Deposited On: | 23 Oct 2020 20:34 | ||||||||||||||||||
Last Modified: | 30 Jan 2021 00:43 |
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