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 Tectonophysics, 630 . pp. 21-32. DOI 10.1016/j.tecto.2014.05.007.

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Supplementary data:


• 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

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
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

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