Magmatism of the troughs behind the New Hebrides island arc (RV Jean Charcot SEAPSO 2 cruise): K-Ar geochronology and petrology

Monjaret, Marie-Claire; Bellón, Hervé; Maillet, Patrick

doi:10.1016/0377-0273(91)90088-h

Cited by 29 publications

(20 citation statements)

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“…There is a consensus that the age and nature of the volcanic and volcano-sedimentary formations sampled in the troughs or on their flanks are linked to the historical evolution of the New Hebrides central chain. However, Monjaret et al (1991) argued that the formation of the NHBAT progressed from south to north, through successive volcano-tectonic phases. The Coriolis troughs developed first (the Futuna Trough around 6.5-6.1 Ma; the Erromango Trough around 4.1 Ma; the Efate Trough around 3.5 Ma) with the formation of the Jean-Charcot troughs (Vot Tande area, 2.7 Ma; Vanikoro area, 2.3 Ma) being more recent.…”

Section: Discussionmentioning

confidence: 99%

“…The date of initiation of the formation of the NHBAT still remains imprecise, in spite of reliable WAr ages (Table III; Monjaret et al, 1991) and micropaleontological determinations (Gérard, 1993). There is a consensus that the age and nature of the volcanic and volcano-sedimentary formations sampled in the troughs or on their flanks are linked to the historical evolution of the New Hebrides central chain.…”

Section: Discussionmentioning

confidence: 99%

“…5.5,5.14, and 5.15. As summarized by Monjaret et al (1991), basalts (4553% SO,) clearly predominate (60% of lavas dredged during the SEAPSO 2 cruise), whereas basaltic andesites (53-60%) and dacites (SO, > 60%) represent 13% and 27% of dredged samples, respectively. These relative abundances did not drastically change after sampling carried out during JSAIYO 89, YOKOSUKA 90 and SAVANES cruises (Table II).…”

Section: Volcanic Petrologymentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Volcanic Petrologymentioning

confidence: 99%

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

Maillet¹,

Ruellan

Gérard³

et al. 1995

Backarc Basins

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“…Volcanic edifices built partly within sedimented summit basins ( Figure 4) along the central axis of the active New Hebrides volcanic chain are largely latest Pliocene and younger (Ͻ 2.5 Ma) in age, but also include latest Miocene to Early Pliocene (5.3 -3.4 Ma) rocks on Erromango (Carney and MacFarlane, 1982;Bellon et al, 1984). Radiometric ages for volcanic rocks dredged from backarc troughs along the eastern flank of the New Hebrides island arc span the interval from 7 Ma to ϳ0.5 Ma (Monjaret et al, 1987(Monjaret et al, , 1991Maillet et al, 1995), overlapping arc activity along both the Maewo -Pentecost trend and the central arc axis.…”

Section: Geologic Contextmentioning

confidence: 99%

Petrography and geologic provenance of sand tempers in prehistoric potsherds from Fiji and Vanuatu, South Pacific

Dickinson

2001

Geoarchaeology

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“…1). Subsequent surveys (Monjaret et al, 1991;Maillet et al, 1995) found no evidence that southern trough extension had evolved to the stage of marginal basin and oceanic crust formation.…”

Section: Introductionmentioning

confidence: 98%

New hydrothermal activity and alkalic volcanism in the backarc Coriolis Troughs, Vanuatu

McConachy

Arculus

Yeats

et al. 2005

Geol

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The Vanuatu Australia Vents Expedition (VAVE) to the Coriolis Troughs in southern Vanuatu during September 2001 aboard the RV Franklin discovered a new hydrothermal vent field-herein informally named Nifonea-and recent alkalic volcanic activity.The Nifonea field in the central Vate Trough was located by coincident light transmission and CH 4 anomalies in a hydrothermal plume of ϳ60 km 2 extent, best developed between 1600 and 1750 m depth at ϳ150 m above the seafloor. Extensive hydrothermal fauna and yellow-brown crusts and mounds cover an area of ϳ1 km 2 . Very fresh, glassy, variably vesicular, sparsely phyric and aphyric basalt, trachybasalt, and basaltic trachyandesite (with ϳ5-6 wt% combined alkalies at ϳ51%-53% SiO 2 and enriched light rare earth elements, Nb, and Zr) samples were dredged from youthful curtain, tube, and sheet flows, plus iron oxyhydroxide deposits. The alkalic composition of lavas in this tectonic setting is unique and attributed to thin ocean crust being developed in an incipient rifting phase involving a relatively low percentage of source-mantle melting. The Coriolis Troughs are among Earth's most youthful backarc basins and thus provide valuable insights to incipient rifting and hydrothermal processes.

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Magmatism of the troughs behind the New Hebrides island arc (RV Jean Charcot SEAPSO 2 cruise): K-Ar geochronology and petrology

Cited by 29 publications

References 8 publications

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

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

Petrography and geologic provenance of sand tempers in prehistoric potsherds from Fiji and Vanuatu, South Pacific

New hydrothermal activity and alkalic volcanism in the backarc Coriolis Troughs, Vanuatu

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