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In search of Gondwana heritage in the Outer Melanesian Arc: no pre-upper Eocene detrital zircons in Viti Levu river sands (Fiji Islands)

Citation

Cluzel, D and Meffre, S, In search of Gondwana heritage in the Outer Melanesian Arc: no pre-upper Eocene detrital zircons in Viti Levu river sands (Fiji Islands), Australian Journal of Earth Sciences, 66, (2) pp. 265-277. ISSN 0812-0099 (2019) [Refereed Article]

Copyright Statement

Copyright 2018 Geological Society of Australia

DOI: doi:10.1080/08120099.2019.1531924

Abstract

Volcanic arcs of the Southwest Pacific, collectively referred to as the Outer Melanesian Arc, are generally thought to result from subduction of the Pacific Plate since the Late Cretaceous. Meanwhile, it is largely accepted that eastward roll-back of the old and dense oceanic plate allowed opening of marginal basins, which isolated large blocks of the former Gondwana margin. Incidentally, some ‘intra-oceanic’ volcanic arcs may have been nucleated on small continental fragments. Detrital zircons collected from sand banks in the mid-reaches of rivers from Viti Levu Island have been analysed for U–Pb geochronology and geochemistry, in order to search for a possible ancient continental arc basement, remnants of a Late Cretaceous arc, and determine the timing and evolution of Fiji arc magmatism. In contrast with some other places of the Outer Melanesian Arc (Solomon, Vanuatu), no pre-upper Eocene zircons have been found. Thus, Gondwana-derived fragments or Late Cretaceous–Paleocene arc remnants are unlikely to form the basement of Viti Levu. Zircon geochemistry confirms the purely intra-oceanic character of volcanic-arc magmatism as well. Variations in some trace-element ratios closely reflect the evolution of Viti Levu Arc from upper Eocene inception to upper Miocene climax and finally Pliocene intra-arc rifting and abandonment.

Item Details

Item Type:Refereed Article
Keywords:zircon, U–Pb, geochemistry, Fiji, Southwest Pacific, Gondwana, volcanic arc
Research Division:Earth Sciences
Research Group:Geology
Research Field:Geochronology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
UTAS Author:Meffre, S (Dr Sebastien Meffre)
ID Code:129973
Year Published:2019 (online first 2018)
Web of Science® Times Cited:3
Deposited By:CODES ARC
Deposited On:2019-01-02
Last Modified:2019-03-18
Downloads:0

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