Recent dredging of a 100 km long ridge along the northernmost part of the Louisiade Plateau (LP) recovered serpentinized peridotites, MORB (mid-ocean-ridge basalt) and volcaniclastic breccia–conglomerates. Clinopyroxene, Cr-spinel and bulk rocks show that the serpentinites are harzburgites to dunites, whereas hornblende phenocrysts from volcaniclastic rocks reflect hydrous, andesitic volcanism. The association of MORB, depleted mantle rocks and fingerprints of hydrous arc magmatism is typical of supra-subduction zone ocean lithosphere formed above a nascent subduction zone. Seismic and high-resolution bathymetry data reveal structures consistent with an extensive east–west elongated ophiolite estimated to have obducted onto the LP between 53 and 80 Ma. This represents a major eastwards continuation of the Papuan Ultramafic Belt and forms a crucial link with ophiolites farther south in New Caledonia, providing support for major subduction initiation events in marginal basins along the northern and eastern margins of Australia and Zealandia in the Palaeocene–Eocene.

Item Type:	Refereed Article
Keywords:	Louisiade Plateau, serpentinized peridotite, Cr-spinel, subduction initiation, SW Pacific, ophiolite, Papuan Ultramafic Belt, New Caledonia, marginal basins
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Igneous and metamorphic petrology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	McCarthy, A (Mr Anders McCarthy)
UTAS Author:	Magri, L (Mr Luca Magri)
UTAS Author:	Sauermilch, I (Miss Isabel Sauermilch)
UTAS Author:	Fox, J (Dr Jodi Fox)
UTAS Author:	Feig, S (Dr Sandrin Feig)
UTAS Author:	Falloon, T (Dr Trevor Falloon)
UTAS Author:	Whittaker, JM (Associate Professor Jo Whittaker)
ID Code:	149130
Year Published:	2022
Web of Science® Times Cited:	2
Deposited By:	Earth Sciences
Deposited On:	2022-03-11
Last Modified:	2022-11-09
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