Geodynamics of an arc-ridge junction: the case of the New Hebrides Arc/North Fiji Basin

Maillet, Patrick; Monzier, Michel; Eissen, Jean‐Philippe; Louat, Rémy

doi:10.1016/0040-1951(89)90050-4

Cited by 28 publications

(30 citation statements)

References 16 publications

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“…This probably confirms the tectonic scenario put forward by Maillet et al (1989) in which the break in the Hunter Ridge in this area is interpreted to be a pull-apart structure due to southward propagation of the main North Fiji Basin spreading centre through the Hunter Ridge.…”

Section: Discussionsupporting

confidence: 72%

“…This propagation may partly explain why the volcanic arc is more poorly defined south of Anatom, and why the depth of the subducted slab is 300 km north of Anatom Island, the southernmost island in the Vanuatu arc, and only 200 km further south than Anatom (Maillet et al, 1989;Monzier et al, submitted). Maillet et al (1989) produced a new bathymetric map, and described the regional structure and geodynamic development of this area. They suggested that the NFB spreading ridge in this region is propagating southward into the Hunter Ridge (Fig.…”

Section: Introduction and Geological Settingmentioning

confidence: 99%

“…la). Within the NFB, fossil transform faults aligned 45°E, and magnetic anomalies oriented 135°E, are believed to be linked to a NW-SE-trending spreading ridge that was active before the presently active ridge came into existence about 3 Ma (Maillet et al, 1989). Since then, the subduction zone has propagated southward from Anatom Island towards the Hunter Ridge.…”

Section: Introduction and Geological Settingmentioning

confidence: 99%

“…We also report olivine and olivine-spinel pair compositions of selected samples from the main magmatic groups identified. The geological setting and the evolution of the NFB is more fully described elsewhere (e.g., Dubois et al, 1977;Dupuy et al, 1982;Monzier et al, 1984;Hamburger and Isacks, 1987;Auzende et al, 1988a, b;Maillet et al, 1989). It is an active, roughly triangular back arc basin located between the Pacific and India-Australian plates; it is bounded to the north by the inactive Vityaz trench, by the Vanuatu arc in the west and the Hunter Ridge-Hunter Fracture Zone (HFZ) and Fiji in the south and east respectively (Fig.…”

Section: Introduction and Geological Settingmentioning

confidence: 99%

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Primitive Inselbogen- und ozeanische Laven von Hunter R�cken und der Hunter BruchZone: die Bedeutung der Zusammensetzung von Glas, Olivin und Spinell

Sigurdsson

Kamenetsky

Crawford

et al. 1992

Mineralogy and Petrology

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SummaryAt its southernmost end, the main spreading centre of the North Fiji Basin is propagating into arc crust of the poorly-known Hunter Ridge. We define nine magmatic groups from major element glass chemistry and olivine and spinel compositions in samples dredged from twenty six sites in this area by the "R/V Academician A. Nesmeyanov" in 1990. These include groups of boninites, island arc tholeiites (IAT), mid-ocean ridge basalts (MORB), enriched mid-ocean ridge basalts (E-MORB), olivine porphyritic andesites and basaltic andesite and Na-rhyolites. Primitive lavas containing highly forsteritic olivine phenocrysts are common in all the groups, except for the rhyolites.We report over 100 glass analyses for dredged rocks from this region, and about 300 olivine-spinel pairs for representatives of all the magmatic groups identified, except the Na-rhyolites.The MORB in this region are probably produced at the propagating spreading centre in the southern part of the North Fiji Basin. Juxtaposition of shallow, hot MORB-source diapirs supplying the MORB in this area, and the sub-arc damp, refractory upper mantle beneath the Hunter Ridge, provides suitable petrogenetic conditions to produce a range of magma types, from island arc tholeiites through to high-Ca boninites. The latter were recovered in eleven dredges.The E-MORB lavas recovered from the extreme southern margin of the North Fiji Basin are shown to be essentially identical to those dredged from adjacent older South Fiji Basin crust. It is hypothesized that the former were either scraped off the South Fiji

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Section: Discussionsupporting

confidence: 72%

Section: Introduction and Geological Settingmentioning

confidence: 99%

Section: Introduction and Geological Settingmentioning

confidence: 99%

Section: Introduction and Geological Settingmentioning

confidence: 99%

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Primitive Inselbogen- und ozeanische Laven von Hunter R�cken und der Hunter BruchZone: die Bedeutung der Zusammensetzung von Glas, Olivin und Spinell

Sigurdsson

Kamenetsky

Crawford

et al. 1992

Mineralogy and Petrology

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“…They terminate south of the latter island, where they merge into the island arc substratum. Furthermore, they are located well away from the N-S axis of the North Fiji Basin active spreading ridge (Monzier et aZ., 1984b;Maillet et al, 1989), and, consequently, any direct influence of this expanding ridge on the petrological evolution of these troughs can be excluded.…”

Section: Discussionmentioning

confidence: 99%

Tectonics, Magmatism, and Evolution of the New Hebrides Backarc Troughs (Southwest Pacific)

Maillet¹,

Ruellan

Gérard³

et al. 1995

Backarc Basins

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In the southwest Pacific, a discontinuous series of narrow and elongated troughs separates the New Hebrides island arc from the adjacent active marginal basin, the North Fiji Basin. This chapter reviews the structural, geophysical, geochronological, and petrological data available for the New Hebrides backarc troughs (NHBAT) and discusses the significance of these structures.A diffuse horst-and-graben morphology, partly obscured in some places by recent volcanic complexes, characterizes the northern Jean-Charcot troughs (JCT). By contrast, the southern Coriolis troughs (CT) show well-developed flat-bottomed grabens. Moreover, no backarc troughs are observed in the central backarc area, adjacent where the d'Entrecasteaux zone collides with the arc.Volcanic rocks dredged in the NHBAT show a wide range of SiO, contents, with highAlzo3 and low-Tio, contents, features typical of their archackarc environments. Trace element analyses indicate a much stronger subduction component in the volcanics of the southern CT than in those of the northern JCT. However, large-ionic-radius-lithophileelement (LILE) (Ba, Rb, Sr) enrichments and high-field-strength-elements (HFSE) (Ta, Nb, Zr, Ti,-Y, Yb) depletions, relative to N-MORB (mid-ocean ridge basalts), are generally observed in most NHBAT volcanics and are features characteristic of island-arc basic and intermediate volcanics. Backarc basin basalts (BABB are scarce; the only occurrence was found in the very northern JCT, indicative of an aborted tendency toward oceanic spreading, between 3.9 and 1.1 Ma W A r dating).Geological long-range inclined asdic (GLORIA) seafloor imagery, manned submersible observations, water chemistry analyses, and sediment heat flow measurements do not provide evidence for widespread hydrothermal activity. or oceanic spreading, in the NHBAT. However. some ferromanganese crusts coating volcanic and volcano-sedimentary formations have a hydrothermal origin (todorokite, birnessite, phillipsite). These hydrothermal crusts are mainly located on the eastem faulted border of the NHBAT.The volcanic-tectonic evolution of the New Hebrides backarc troughs primanly results from the concomitant effects of nearby subduction (along the New Hebrides subduction zone) and spreading (in the central North Fiji basin) and secondarily from the after-effects of the collision of the d'Entrecasteaux zone with the arc. The NHBAT represent the very first stage of backarc crustal extension. characterized by volcanics with predominantly island-arc tholeiite and some BABB compositional features.

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Propagation of back‐arc extension into the arc lithosphere in the southern New Hebrides volcanic arc

Patriat

Collot

Danyushevsky

et al. 2015

Geochem Geophys Geosyst

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New geophysical data acquired during three expeditions of the R/V Southern Surveyor in the southern part of the North Fiji Basin allow us to characterize the deformation of the upper plate at the southern termination of the New Hebrides subduction zone, where it bends eastward along the Hunter Ridge. Unlike the northern end of the Tonga subduction zone, on the other side of the North Fiji Basin, the 908 bend does not correspond to the transition from a subduction zone to a transform fault, but it is due to the progressive retreat of the New Hebrides trench. The subduction trench retreat is accommodated in the upper plate by the migration toward the southwest of the New Hebrides arc and toward the south of the Hunter Ridge, so that the direction of convergence remains everywhere orthogonal to the trench. In the back-arc domain, the active deformation is characterized by propagation of the back-arc spreading ridge into the Hunter volcanic arc. The N-S spreading axis propagates southward and penetrates in the arc, where it connects to a sinistral strike-slip zone via an oblique rift. The collision of the Loyalty Ridge with the New Hebrides arc, less than two million years ago, likely initiated this deformation pattern and the fragmentation of the upper plate. In this particular geodynamic setting, with an oceanic lithosphere subducting beneath a highly sheared volcanic arc, a wide range of primitive subduction-related magmas has been produced including adakites, island arc tholeiites, back-arc basin basalts, and medium-K subduction-related lavas.

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Geodynamics of an arc-ridge junction: the case of the New Hebrides Arc/North Fiji Basin

Cited by 28 publications

References 16 publications

Primitive Inselbogen- und ozeanische Laven von Hunter R�cken und der Hunter BruchZone: die Bedeutung der Zusammensetzung von Glas, Olivin und Spinell

Primitive Inselbogen- und ozeanische Laven von Hunter R�cken und der Hunter BruchZone: die Bedeutung der Zusammensetzung von Glas, Olivin und Spinell

Tectonics, Magmatism, and Evolution of the New Hebrides Backarc Troughs (Southwest Pacific)

Propagation of back‐arc extension into the arc lithosphere in the southern New Hebrides volcanic arc

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