Mortimer N. auteur aut IRD Gans P. B. auteur aut IRD Palin J. M. auteur aut IRD Herzer R. H. auteur aut IRD Pelletier Bernard auteur aut IRD Monzier Michel auteur aut IRD text journalArticle eng text/pdf born digital access This paper presents 34 geochemical analyses, 24 Ar-Ar ages, and two U-Pb ages of igneous rocks from the back-arc basins and submarine ridges in the Coral Sea-New Caledonia region. The D'Entrecasteaux Ridge is a composite structural feature. Primitive arc tholeiites of Eocene age (34-56 Ma) are present along a 200 km length of the ridge and arguably were part of the initial line of subduction inception between Fiji and the Marianas; substantial Eocene arc edifices are only evident at the eastern end where Bougainville Guyot andesite breccias are dated at 40 +/- 2 Ma. The South Rennell Trough is confidently identified as a 28-29 Ma (early Oligocene) fossil spreading ridge, and hence, the flanking Santa Cruz and D'Entrecasteaux basins belong in the group of SW Pacific Eocene-Early Miocene back-arc basins that include the Solomon Sea, North Loyalty, and South Fiji basins. The rate and duration of spreading in the North Loyalty Basin is revised to 43 mm/yr between 28 and 44 Ma, longer and faster than previously recognized. The direction of its opening was to the southeast, that is, parallel to the continent-ocean boundary and perpendicular to the direction of coeval New Caledonia ophiolite emplacement. Medium-and high-K alkaline lavas of 23-25 Ma (late Oligocene) age on the northern Norfolk Ridge are an additional magmatic response to Pacific trench rollback. specialized NOUVELLE CALEDONIE PACIFIQUE 064 33 7 1386-1407 2014 0278-7407 https://www.documentation.ird.fr/hor/fdi:010062481 10.1002/2014tc003598 0278-7407 [F B010062481] https://www.documentation.ird.fr/hor/fdi:010062481 https://www.documentation.ird.fr/intranet/publi/2014/09/010062481.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2014-10-02 2017-08-23 fdi:010062481 fre