Crustal structure of the Kermadec arc from MANGO seismic refraction profiles.

Bassett, Dan, Kopp, Heidrun , Sutherland, Rupert, Henrys, Stuart, Watts, Anthony B., Timm, Christian, Scherwath, Martin, Grevemeyer, Ingo and de Ronde, Cornel E. J. (2016) Crustal structure of the Kermadec arc from MANGO seismic refraction profiles. Open Access Journal of Geophysical Research: Solid Earth, 121 (10). 7514-7546 . DOI 10.1002/2016JB013194.

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Abstract

Three active-source seismic refraction profiles are integrated with morphological and potential field data to place the first regional constraints on the structure of the Kermadec subduction zone. These observations are used to test contrasting tectonic models for an along-strike transition in margin structure previously known as the 32°S boundary. We use residual bathymetry to constrain the geometry of this boundary and propose the name Central Kermadec Discontinuity (CKD). North of the CKD, the buried Tonga Ridge occupies the forearc with VP 6.5–7.3 km s-1 and residual free-air gravity anomalies constrain its latitudinal extent (north of 30.5°S), width (110 ± 20 km) and strike (~005° south of 25°S). South of the CKD the forearc is structurally homogeneous down-dip with VP 5.7–7.3 km s-1. In the Havre Trough backarc, crustal thickness south of the CKD is 8-9 km, which is up-to 4 km thinner than the northern Havre Trough and at least 1 km thinner than the southern Havre Trough. We suggest that the Eocene arc did not extend along the current length of the Tonga-Kermadec trench. The Eocene arc was originally connected to the Three Kings Ridge and the CKD was likely formed during separation and easterly translation of an Eocene arc substrate during the early Oligocene. We suggest that the first-order crustal thickness variations along the Kermadec arc were inherited from before the Neogene and reflect Mesozoic crustal structure, the Cenozoic evolution of the Tonga-Kermadec-Hikurangi margin and along-strike variations in the duration of arc volcanism.

Document Type: Article
Additional Information: The data analyzed in this study will be made available on request (dbassett@ucsd.edu). - WOS:000388441800030
Keywords: Tonga Kermadec; South Fiji Basin; subduction plate boundary; seismic refraction; crustal structure; tectonics; RV Sonne, SO215
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2016JB013194
ISSN: 0148-0227
Expeditions/Models/Experiments:
Date Deposited: 01 Sep 2016 12:53
Last Modified: 04 Apr 2019 14:00
URI: http://oceanrep.geomar.de/id/eprint/33685

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