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The Louisiade ophiolite: a missing link in the western Pacific

journal contribution
posted on 2023-05-21, 06:17 authored by McCarthy, A, Luca MagriLuca Magri, Isabel Sauermilch, Jodi FoxJodi Fox, Seton, M, Mohn, G, Tugend, J, Sandrin FeigSandrin Feig, Trevor FalloonTrevor Falloon, Joanne WhittakerJoanne Whittaker
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.

History

Publication title

Terra Nova

Volume

34

Pagination

146-154

ISSN

0954-4879

Department/School

Institute for Marine and Antarctic Studies

Publisher

Wiley-Blackwell Publishing Ltd.

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

© 2022 John Wiley

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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