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Published June 2022 | Published
Journal Article Open

Timing of Eocene compressional plate failure during subduction initiation, northern Zealandia, southwestern Pacific

Abstract

Rapid onset of subduction tectonics across the western Pacific convergent margins in the early Eocene was followed by a slower phase of margin growth of the proto Tonga-Kermadec subduction system north of Zealandia during a middle Eocene phase to tectonic adjustment. We present new age constraints from International Ocean Discovery Program Expedition 371 borehole data on deformation events in northern Zealandian sediments that document the formation of the convergent margin boundary northwest of New Zealand. The deformation shows a shortening event that lasted up to 20 myr and acted over distances of ∼1000 km inboard of the evolving plate margin, just northwest of New Zealand. Multichannel seismic profiles tied to our new borehole sites show shortening occurred predominantly between 45 Ma and 35 Ma with some deformation related to slope failure continuing into the Oligocene. The termination of shortening is linked to opening of the backarc basins of the southwest Pacific and the migration of the Tonga-Kermadec Trench to the east which may have removed the structural evidence of the Eocene plate margin. Paleogene deformation observed inboard of the evolving proto Tonga-Kermadec subduction system indicates that the lithosphere of northern Zealandia, a region of thin continental crust, was strong enough to act as a stress guide. Compressive stresses that caused intra plate folding and faulting developed behind the initiating subduction system with the finite period of deformation indicating the time frame over which an active convergent margin lay along the northern margin of Zealandia.

Additional Information

© The Author(s) 2022. Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Revision received: 13 July 2021; Received: 13 December 2021; Accepted: 06 January 2022; Published: 28 January 2022. We thank the International Ocean Discovery Program (IODP); the onboard personnel of R/V JOIDES Resolution on Expedition 371; shore-based proponents; and the scientists who conducted the site surveys on voyage TAN1409. This work was funded by the U.S. National Science Foundation; IODP participating countries; New Zealand, France, and New Caledonia. MG was supported by the National Science Foundation (OCE-2049086). LA acknowledges support from project PID2019-105537RB-I00 (Spanish Ministry of Science and Innovation and FEDER funds) and a 2017 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation. MG thanks the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—that granted his participation in the IODP Expedition 371″. ED is supported by Deutsche Forschungsgemeinschaft (DFG; German research foundation)—projektnummer 408178503. H-HH acknowledges support from Japan Agency for Marine-Earth Science and Technology and Peter Buck Postdoctoral Fellowship of the National Museum of Natural History, Smithsonian Institution. We thank Ron Hackney and an anonymous reviewer for the helpful edits and suggestions that have improved the manuscript. DATA AVAILABILITY. Seismic reflection data were compiled into an available database resource (Sutherland et al. 2012) and can be obtained from GNS Science (data.gns.cri.nz/pbe) or NZ Petroleum and Minerals (data.nzpam.govt.nz). International Ocean Discovery Program Expedition 371 borehole data are available via IODP's LIMS online report portal website https://web.iodp.tamu.edu/LORE/. Borehole velocity and density models and examples of tested borehole tie to seismic models are available from the data repository, https://zenodo.org/badge/latestdoi/436458689.

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023