Cretaceous fore-arc basalts from the Tonga arc: Geochemistry and implications for the tectonic history of the SW Pacific.

Falloon, Trevor J., Meffre, Sebastian, Crawford, Anthony J., Hoernle, Kaj , Hauff, Folkmar, Bloomer, Sherman H. and Wright, Dawn J. (2014) Cretaceous fore-arc basalts from the Tonga arc: Geochemistry and implications for the tectonic history of the SW Pacific. Open Access Tectonophysics, 630 . pp. 21-32. DOI 10.1016/j.tecto.2014.05.007.

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Supplementary data:

Abstract

Highlights:
• The geochemistry of a Cretaceous Tongan fore-arc basalt (FAB) suite is reported.
• The Tonga FAB suite is very similar to the Poya Terrane basalts of New Caledonia.
• Similar geochemistry to IBM FAB but not associated with subduction initiation
• Possibly a remnant of the hypothesized back-arc East New Caledonia Basin

Abstract:
The Tonga fore-arc preserves a complex history of subduction initiation, back-arc basin formation and arc volcanism which has extended from the Cretaceous to the present. In this paper, we discuss the geochemistry of a Cretaceous basalt/dolerite/gabbro suite recovered in two dredges from the Tonga fore-arc at ~ 19°S. The geochemistry of the Tonga fore-arc suite is unlike that of the uniformly depleted MORB basalts of the subducting Pacific Plate and therefore is unlikely to be accreted from Pacific Cretaceous crust. The ~ 102 Ma age obtained for one Tongan fore-arc dolerite is contemporaneous with a major phase of Cretaceous subduction-related volcanism, recorded both in detrital zircon age populations and associated volcanics from New Caledonia and New Zealand. We believe that the Tonga fore-arc basalts are a remnant of a hypothesized, once extensive Cretaceous back-arc basin, called the East New Caledonia Basin, which we propose to have existed from ~ 102 to 50 Ma. The allochthonous Poya Terrane of New Caledonia is geochemically very similar to the Tonga fore-arc basalts and represents a younger (~ 84–55 Ma) remnant of the same basin. Subduction-related Cretaceous volcanics from the SW Pacific, representing both arc and back-arc settings, all appear to have similar Zr/Nb values, suggesting a common mantle component in their petrogenesis. The Tonga fore-arc basalts are also similar to fore-arc basalts recovered from the Izu-Bonin-Mariana fore-arc, but unlike these basalts they are not associated with subduction initiation.

Document Type: Article
Additional Information: WOS:000341548900003
Keywords: Tonga; fore-arc; basalts; Poya Terrane; SW Pacific; subduction-related magma genesis; 1996 RV Melville voyage, Boomerang Leg 8
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.tecto.2014.05.007
ISSN: 0040-1951
Projects: Future Ocean
Date Deposited: 23 May 2014 11:53
Last Modified: 05 Jan 2018 10:18
URI: http://oceanrep.geomar.de/id/eprint/24627

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