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The metamorphic sole of New Caledonia ophiolite: 40Ar/ 39Ar, U-Pb, and geochemical evidence for subduction inception at a spreading ridge

Citation

Cluzel, D and Jourdan, F and Meffre, S and Maurizot, P and Lesimple, S, The metamorphic sole of New Caledonia ophiolite: 40Ar/ 39Ar, U-Pb, and geochemical evidence for subduction inception at a spreading ridge, Tectonics, 31, (3) Article TC3016. ISSN 0278-7407 (2012) [Refereed Article]

Copyright Statement

Copyright 2012 American Geophysical Union

DOI: doi:10.1029/2011TC003085

Abstract

Amphibolite lenses that locally crop out below the serpentinite sole at the base of the ophiolite of New Caledonia (termed Peridotite Nappe) recrystallized in the high-temperature amphibolite facies and thus sharply contrast with blueschists and eclogites of the Eocene metamorphic complex. Amphibolites mostly display the geochemical features of MORB with a slight Nb depletion and thus are similar to the youngest (Late Paleocene-Eocene) BABB components of the allochthonous Poya Terrane. Thermochronological data from hornblende ( 40Ar/ 39Ar), zircon, and sphene (U-Pb) suggest that these mafic rocks recrystallized at ∼56Ma. Using various geothermobarometers provides a rough estimate of peak recrystallization conditions of ∼0.5GPa at ∼800-950C. The thermal gradient inferred from the metamorphic assemblage (∼60°Ckm -1), geometrical relationships, and geochemical similarity suggest that these mafic rocks belong to the oceanic crust of the lower plate of the subduction/obduction system and recrystallized when they subducted below young and hot oceanic lithosphere. They were detached from the down-going plate and finally thrust onto unmetamorphosed Poya Terrane basalts. This and the occurrence of slab melts at ∼53Ma suggest that subduction inception occurred at or near to the spreading ridge of the South Loyalty Basin at ∼56Ma. © 2012. American Geophysical Union. All Rights Reserved.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Tectonics
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Meffre, S (Dr Sebastien Meffre)
ID Code:81411
Year Published:2012
Funding Support:Australian Research Council (CE0561595)
Web of Science® Times Cited:25
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2012-12-05
Last Modified:2013-04-10
Downloads:0

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