Basalts erupted along the Tongan fore-arc during subduction initiation: evidence from geochronology of dredged rocks from the Tonga fore-arc and trench

Meffre, S., Falloon, T. , Crawford, J., Hoernle, Kaj, Hauff, Folkmar, Duncan, R. A., Bloomer, S. H. and Wright, D. J. (2012) Basalts erupted along the Tongan fore-arc during subduction initiation: evidence from geochronology of dredged rocks from the Tonga fore-arc and trench Geochemistry Geophysics Geosystems, 13 . Q12003. DOI 10.1029/2012GC004335.

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Abstract

A wide variety of different rock types were dredged from the Tonga fore arc and trench between 8000 and 3000 m water depths by the 1996 Boomerang voyage. 40Ar-39Ar whole rock and U-Pb zircon dating suggest that these fore arc rocks were erupted episodically from the Cretaceous to the Pliocene (102 to 2 Ma). The geochemistry suggests that MOR-type basalts and dolerites were erupted in the Cretaceous, that island arc tholeiites were erupted in the Eocene and that back arc basin and island arc tholeiite and boninite were erupted episodically after this time. The ages generally become younger northward suggesting that fore arc crust was created in the south at around 48–52 Ma and was extended northward between 35 and 28 Ma, between 9 and 15 Ma and continuing to the present-day. The episodic formation of the fore arc crust suggested by this data is very different to existing models for fore arc formation based on the Bonin-Marianas arc. The Bonin-Marianas based models postulate that the basaltic fore arc rocks were created between 52 and 49 Ma at the beginning of subduction above a rapidly foundering west-dipping slab. Instead a model where the 52 Ma basalts that are presently in a fore arc position were created in the arc-back arc transition behind the 57–35 Ma Loyalty-Three Kings arc and placed into a fore arc setting after arc reversal following the start of
collision with New Caledonia is proposed for the oldest rocks in Tonga. This is followed by growth of the fore arc northward with continued eruption of back arc and boninitic magmas after that time.

Document Type: Article
Additional Information: WOS:000312094300002
Keywords: Tonga; U-Pb geochronology; back-arc basin basalts; fore arc; subduction-related magma genesis; trench; PLATE TECTONIC EVOLUTION; PHILIPPINE SEA PLATE; SOUTH FIJI BASIN; NEW-CALEDONIA; SW PACIFIC; MANTLE WEDGE; GEOCHEMICAL EVOLUTION; NEW-ZEALAND; OPHIOLITE; LAVAS
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1029/2012GC004335
ISSN: 1525-2027
Projects: Future Ocean
Date Deposited: 29 Nov 2012 14:38
Last Modified: 01 Mar 2018 12:22
URI: http://eprints.uni-kiel.de/id/eprint/19406

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