U–Pb zircon dating of post-obduction volcanic-arc granitoids and a granulite-facies xenolith from New Caledonia. Inference on Southwest Pacific geodynamic models

Paquette, Jean‐Louis; Cluzel, Dominique

doi:10.1007/s00531-006-0127-1

Cited by 39 publications

(57 citation statements)

References 15 publications

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“…The five analyzed potassic intraplate 23–25 Ma (Oligocene) lavas from the Norfolk Ridge (samples from GO5, 10, 13, 14, and 16) have no known correlatives in New Caledonia. However postobduction 24 Ma and 27 Ma granitoid stocks do occur in New Caledonia [ Paquette and Cluzel , ; Cluzel et al ., ]. The most mafic of these samples is a gabbro from the Saint Louis body.…”

Section: Discussionmentioning

confidence: 99%

Eocene and Oligocene basins and ridges of the Coral Sea-New Caledonia region: Tectonic link between Melanesia, Fiji, and Zealandia

et al. 2014

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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.

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Section: Discussionmentioning

confidence: 99%

Eocene and Oligocene basins and ridges of the Coral Sea-New Caledonia region: Tectonic link between Melanesia, Fiji, and Zealandia

et al. 2014

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“…1). The south-westward emplacement of the Peridotite Nappe is considered to have occurred between 37 and 27 Ma (Cluzel et al 2001Paquette and Cluzel 2007;Maurizot et al 2009). Outcropping peridotites then quickly underwent strong water-rock interactions under a hot and humid climate, favouring the formation of a thick laterite cover ( Fig.…”

Section: Geological Settingmentioning

confidence: 99%

Nickel dispersion and enrichment at the bottom of the regolith: formation of pimelite target-like ores in rock block joints (Koniambo Ni deposit, New Caledonia)

et al. 2015

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International audienceIn New Caledonian Ni deposits, the richest Ni silicate ores occur in fractures within the bedrock and saprolite, generally several tens of meters to hundred meters below the present-day surface. Fracture-related Ni silicate ore accounts for high Ni grades, at least a few weight percent above the average exploited grade (2.5 %). These Ni-rich veins are affected by active dissolution-precipitation processes at the level of the water table. Ni in solution is precipitated as silicates in thin layer cementing joints. This mineralization is characterized by chemical and mineralogical concentric zoning with an outer green rim around an inner white zone composed, from the edge to the centre of the block, (i) a highly oxidized and altered zone, (ii) a green pure Ni-rich pimelite zone, (iii) a zone (limited to a few centimetres) with a mixture of Ni-poor kerolite and Ni-rich pimelite and intermediate colours and (iv) a large white Mg-kerolite mineralization zone. This study proposes that the concentric zonation results from evapo-precipitation process related to alternate periods of hydration and drying, induced by water table movements. This extensive dispersion of Ni in concentrically zoned ores can partly explain the rather monotonous Ni grade of the bulk exploitation at the base of the regolith with values between 2 and 3 wt%

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“…Southwest vergent thrusts and folds deform the sedimentary pile along the foot of the steep submarine slope west of the island [ Rigolot , ; Lafoy et al ., ], but it is unclear whether these structures reflect lithospheric convergence or only local contraction at the front of large gravitational slides [ Lafoy et al ., ; Chardon and Chevillotte , ]. Further southwest, underneath the mid‐Cenozoic unconformity, a structure with half grabens up to ~40 km wide has been identified along some seismic lines, supporting the view that the northern part of the New Caledonia Basin is floored by thinned continental crust [ Lafoy et al ., , ; Paquette and Cluzel , ].…”

Section: Geological Settingmentioning

confidence: 99%

“…The related thrusts are shown as dashed lines in Figure a to emphasize that there is no direct evidence for their existence to date (see section 2.3). We leave it open whether convergence along the western margin of the Grande Terre ever involved the subduction of an oceanic lithosphere [ Paquette and Cluzel , ; Cluzel et al ., ]. If so, this ocean would already be subducted at the stage shown in Figure a, but we do not mean that this was necessarily the case as early as ~34 Ma.…”

Section: Obduction Tectonics In New Caledoniamentioning

confidence: 99%

The emplacement of the Peridotite Nappe of New Caledonia and its bearing on the tectonics of obduction

2016

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The Peridotite Nappe of New Caledonia is one of the few ophiolites worldwide that escaped collisional orogeny after obduction. Here we describe the deformation associated with serpentinization in two klippes of the nappe in northwestern New Caledonia. The klippes are flat lying and involve S/SW vergent reverse‐slip shear zones which are true compressional structures in origin. Further northeast, the nappe is folded in association with the development of a steep schistosity in low‐grade metasediments. This difference in structural style indicates that the Peridotite Nappe experienced compression at greater depths toward its root zone, suggesting a “push from the rear” mechanism of emplacement. This supports the view that the nappe has been emplaced through horizontal contraction sustained by plate convergence. We establish a crustal‐scale cross section at the end of the obduction event, before Neogene extension. This involves a large fold nappe of high‐pressure rocks bounded from below by a major thrust. Furthermore, we show that obduction in New Caledonia occurred through dextral oblique convergence. Oblique convergence probably resulted from the initial obliquity between the subduction trench and the continental ribbon that became incorporated in it. This obliquity can solve the paradox of the Peridotite Nappe seemingly being emplaced at the same time the high‐pressure rocks were exhumed. Oblique convergence together with focused erosional denudation on the northeastern flank of the island led to exhumation of the metamorphic rocks in a steep fold nappe rising through the rear part of the orogen.

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U–Pb zircon dating of post-obduction volcanic-arc granitoids and a granulite-facies xenolith from New Caledonia. Inference on Southwest Pacific geodynamic models

Abstract: To cite this version:Jean-Louis Paquette, Dominique Cluzel. U-Pb zircon dating of post-obduction volcanic-arc granitoids and a granulite-facies xenolith from New Caledonia. Inference on Southwest Pacific geodynamic models

Cited by 39 publications

References 15 publications

Eocene and Oligocene basins and ridges of the Coral Sea-New Caledonia region: Tectonic link between Melanesia, Fiji, and Zealandia

Eocene and Oligocene basins and ridges of the Coral Sea-New Caledonia region: Tectonic link between Melanesia, Fiji, and Zealandia

Nickel dispersion and enrichment at the bottom of the regolith: formation of pimelite target-like ores in rock block joints (Koniambo Ni deposit, New Caledonia)

The emplacement of the Peridotite Nappe of New Caledonia and its bearing on the tectonics of obduction

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