Eocene pre- and syn-obduction tectonics in New Caledonia (Southwest Pacific), a case for oblique subduction, transcurrent tectonics and oroclinal bending; structural and paleomagnetic evidence

Cluzel, Dominique; Iseppi, Marion; Chen, Yan

doi:10.1016/j.tecto.2021.228875

Cited by 4 publications

(1 citation statement)

References 76 publications

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“…From c. 56 Ma to c. 34 Ma, the South Loyalty Basin, originally located to the east of the Norfolk Ridge, subducted northeastward and generated the HP-LT metamorphic belt of northern New Caledonia. Subduction blockage by the northern Norfolk Ridge at the end of the Eocene period (Figure 12a) provoked the back jump and initiation of the subduction of the New Caledonia Basin (NCB) (Figure 12b), which accompanied the 60 • counterclockwise rotation of the northern Norfolk Ridge [56]. During the NCB subduction, the Late Oligocene granodiorite melts were produced in the mantle wedge, which was variably modified by slab melts.…”

Section: Summary Of Evolutionmentioning

confidence: 99%

Petrology and Geochemistry of an Unusual Granulite Facies Xenolith of the Late Oligocene Post-Obduction Koum Granodiorite (New Caledonia, Southwest Pacific): Geodynamic Inferences

Cluzel,

Trotet,

Paquette

2024

Minerals

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Pressure–temperature estimates of a xenolith found within a post-obduction granodiorite in southern New Caledonia provide evidence for subcrustal, granulite facies, peak crystallisation conditions (ca. 850 °C—8.5 ± 1.0 kbar), followed by isobaric cooling to 700 °C, and final decompression with partial rehydration at ca. 650 °C—3.5 kbar. The xenolith, dated at 24.7 Ma (U-Pb zircon), i.e., the same age as the granodiorite host rock, has low SiO2 (35.5 wt%) and high Al2O3 (33.2 wt%) contents, suggesting that it is the restite of a previous melting episode, while the elevated Ca (Ba and Sr) contents suggest mantle metasomatism. Although the concentrations of Rb, K, Ca, Ba, and Sr have been strongly modified, some geochemical (REE patterns and some “immobile” trace element ratios) and isotopic (Sr and Nd isotopic ratios, U-Pb zircon age) characteristics of the granulite facies xenolith are similar to those of the xenoliths found in other Late Oligocene intrusions in southern New Caledonia; therefore, this rock is interpreted to be related to an early magmatic episode. The rock protolith was emplaced and equilibrated at the base of the crust where it underwent ductile deformation. Younger ascending magma picked it up and they eventually crystallised together at a shallow crustal level, near the tectonic sole of the ophiolite. The recrystallisation and ductile deformation at ~8.5 kbar suggest that a rheological discontinuity existed at about 25–28 km, probably representing the Moho. It is concluded that a continental crust of normal thickness must have existed beneath New Caledonia at about 24 Ma, i.e., 10 Ma after obduction.

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Section: Summary Of Evolutionmentioning

confidence: 99%

Petrology and Geochemistry of an Unusual Granulite Facies Xenolith of the Late Oligocene Post-Obduction Koum Granodiorite (New Caledonia, Southwest Pacific): Geodynamic Inferences

Cluzel,

Trotet,

Paquette

2024

Minerals

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Geometry and deformation of the sole of a large obducted ophiolitic unit: insights from surface geology and airborne electromagnetics – Peridotite Nappe, New Caledonia

Le Bayon,

Maurizot,

Reninger

et al. 2023

New Zealand Journal of Geology and Geophysics

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Anatomy of an obducted ultramafic unit (Tiébaghi Massif – Peridotite Nappe – New Caledonia): Polyphase brittle tectonics constrained by fault-slip data and crack seal mineralogy

Maurizot,

Robineau,

Jeanpert

et al. 2023

New Zealand Journal of Geology and Geophysics

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Eocene pre- and syn-obduction tectonics in New Caledonia (Southwest Pacific), a case for oblique subduction, transcurrent tectonics and oroclinal bending; structural and paleomagnetic evidence

Abstract: Please cite this article as: C. Dominique, I. Marion and C. Yan, Eocene pre-and synobduction tectonics in New Caledonia (Southwest Pacific), a case for oblique subduction, transcurrent tectonics and oroclinal bending; structural and paleomagnetic evidence, Tectonophysics (2021),

Cited by 4 publications

References 76 publications

Petrology and Geochemistry of an Unusual Granulite Facies Xenolith of the Late Oligocene Post-Obduction Koum Granodiorite (New Caledonia, Southwest Pacific): Geodynamic Inferences

Petrology and Geochemistry of an Unusual Granulite Facies Xenolith of the Late Oligocene Post-Obduction Koum Granodiorite (New Caledonia, Southwest Pacific): Geodynamic Inferences

Geometry and deformation of the sole of a large obducted ophiolitic unit: insights from surface geology and airborne electromagnetics – Peridotite Nappe, New Caledonia

Anatomy of an obducted ultramafic unit (Tiébaghi Massif – Peridotite Nappe – New Caledonia): Polyphase brittle tectonics constrained by fault-slip data and crack seal mineralogy

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