S-to-P receiver function imaging of lithospheric discontinuities in New Zealand at the Hikurangi subduction zone
S-to-P receiver function imaging of lithospheric discontinuities in New Zealand at the Hikurangi subduction zone
Subduction zones are important regions for understanding plate tectonic processes. New Zealand experiences slow slip, volcanism, and back-arc rifting, and has evidence of large megathrust events and tsunamis. We use S-to-P receiver functions to image lithospheric discontinuities beneath the North Island of New Zealand. A positive discontinuity interpreted as the Moho is imaged at 15–30 ± 3 km depth beneath the overriding Australian Plate. In some locations, near the interface of the Pacific and Australian Plates, we don't image the Pacific Plate Moho, and the Australian Plate Moho is faint or absent. The former could be related to the increasing dip or eclogitization of the Pacific Plate crust, and the latter is likely related to mantle wedge serpentinization. A negative velocity discontinuity associated with the lithosphere-asthenosphere boundary (LAB) of the Australian Plate is imaged at 63–80 ± 8 km depth across the northwestern side of the island. Negative discontinuities are imaged beneath the southern Pacific Plate at 85–105 ± 10 km and 130 ± 13 km depth, representing either a mid-lithospheric discontinuity (MLD) and a deeper LAB, or more likely a shallow LAB and a deeper artifact, given that the latter is better aligned with previous work. Beneath the Australian Plate, asthenospheric melt is inferred in the northwest beneath several regions of active volcanism. Beneath the Pacific Plate, asthenospheric melt is inferred near the trench, also corresponding to the transition to where the plates become locked; therefore, plate locking could be related to the buoyancy of the melt.
lithosphere-asthenosphere boundary, Moho, New Zealand, receiver function, S-to-P, subduction zone
Buffett, William A.
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Rychert, Catherine A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
18 March 2025
Buffett, William A.
0a4dd24c-231b-4829-a2f2-afe6d1cf8cb2
Rychert, Catherine A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Buffett, William A., Rychert, Catherine A. and Harmon, Nicholas
(2025)
S-to-P receiver function imaging of lithospheric discontinuities in New Zealand at the Hikurangi subduction zone.
Geochemistry, Geophysics, Geosystems, 26 (3), [e2024GC011897].
(doi:10.1029/2024GC011897).
Abstract
Subduction zones are important regions for understanding plate tectonic processes. New Zealand experiences slow slip, volcanism, and back-arc rifting, and has evidence of large megathrust events and tsunamis. We use S-to-P receiver functions to image lithospheric discontinuities beneath the North Island of New Zealand. A positive discontinuity interpreted as the Moho is imaged at 15–30 ± 3 km depth beneath the overriding Australian Plate. In some locations, near the interface of the Pacific and Australian Plates, we don't image the Pacific Plate Moho, and the Australian Plate Moho is faint or absent. The former could be related to the increasing dip or eclogitization of the Pacific Plate crust, and the latter is likely related to mantle wedge serpentinization. A negative velocity discontinuity associated with the lithosphere-asthenosphere boundary (LAB) of the Australian Plate is imaged at 63–80 ± 8 km depth across the northwestern side of the island. Negative discontinuities are imaged beneath the southern Pacific Plate at 85–105 ± 10 km and 130 ± 13 km depth, representing either a mid-lithospheric discontinuity (MLD) and a deeper LAB, or more likely a shallow LAB and a deeper artifact, given that the latter is better aligned with previous work. Beneath the Australian Plate, asthenospheric melt is inferred in the northwest beneath several regions of active volcanism. Beneath the Pacific Plate, asthenospheric melt is inferred near the trench, also corresponding to the transition to where the plates become locked; therefore, plate locking could be related to the buoyancy of the melt.
Text
Geochem Geophys Geosyst - 2025 - Buffett - S‐to‐P Receiver Function Imaging of Lithospheric Discontinuities in New Zealand
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Accepted/In Press date: 20 December 2024
Published date: 18 March 2025
Keywords:
lithosphere-asthenosphere boundary, Moho, New Zealand, receiver function, S-to-P, subduction zone
Identifiers
Local EPrints ID: 501160
URI: http://eprints.soton.ac.uk/id/eprint/501160
ISSN: 1525-2027
PURE UUID: 65a4de1e-ac87-4182-b862-37492afe502b
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Date deposited: 27 May 2025 16:59
Last modified: 22 Aug 2025 02:01
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