Composition of back-arc basin volcanics, Valu Fa Ridge, Lau Basin

Evidence for a slab-derived component in their mantle source

G. A. Jenner, P. A. Cawood, M. Rautenschlein, W. M. White

Research output: Contribution to journalArticleResearchpeer-review

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Abstract

Samples dredged from 2 localities near the crest of the Valu Fa ridge, an active back-arc basin spreading centre in the Lau Basin, consist of highly vesicular lava fragments of andesitic composition. The samples are characterized by rare, euhedral An85 plagioclase phenocrysts in a hypocrystalline groundmass of An60 plagioclase laths, brown glass and rare subhedral clinopyroxene. Samples from within and, to a lesser extent, between the dredge hauls show remarkable isotopic and chemical homogeneity, with: 87Sr/86Sr - 0.70330 ± 2; 143Nd/144Nd - 0.51303 ± 2; 206Pb/204Pb - 18.65 ± 2; 207Pb/204Pb - 15.55 ± 1; 208Pb/204Pb - 38.34 ± 4; Sr - 165 ppm; Rb - 7 ppm; Cs - 0.17 ppm; K - 3300 to 4200 ppm; Ba - 96 ppm; and REE - LREE depleted with 12-18 × chondritic abundances. On Sr-Nd, Pb-Pb and Sr-Pb plots the volcanics lie just within or on the edge of the MORB fields, overlapping with island-arc volcanics from the Marianas and Tonga. Compared with MORB and ocean-island basalts, the samples show alkali-element enrichment relative to REE and higher Cs relative to Rb. The isotopic and geochemical characteristics of the Valu Fa Ridge volcanics clearly indicate a minor, but significant, slab-derived component in the back-arc basin mantle source.

Original languageEnglish
Pages (from-to)209-222
Number of pages14
JournalJournal of Volcanology and Geothermal Research
Volume32
Issue number1-3
DOIs
Publication statusPublished - 1 Jan 1987
Externally publishedYes

Cite this

@article{c6580a47152c4da3a363b8e95c55ccd1,
title = "Composition of back-arc basin volcanics, Valu Fa Ridge, Lau Basin: Evidence for a slab-derived component in their mantle source",
abstract = "Samples dredged from 2 localities near the crest of the Valu Fa ridge, an active back-arc basin spreading centre in the Lau Basin, consist of highly vesicular lava fragments of andesitic composition. The samples are characterized by rare, euhedral An85 plagioclase phenocrysts in a hypocrystalline groundmass of An60 plagioclase laths, brown glass and rare subhedral clinopyroxene. Samples from within and, to a lesser extent, between the dredge hauls show remarkable isotopic and chemical homogeneity, with: 87Sr/86Sr - 0.70330 ± 2; 143Nd/144Nd - 0.51303 ± 2; 206Pb/204Pb - 18.65 ± 2; 207Pb/204Pb - 15.55 ± 1; 208Pb/204Pb - 38.34 ± 4; Sr - 165 ppm; Rb - 7 ppm; Cs - 0.17 ppm; K - 3300 to 4200 ppm; Ba - 96 ppm; and REE - LREE depleted with 12-18 × chondritic abundances. On Sr-Nd, Pb-Pb and Sr-Pb plots the volcanics lie just within or on the edge of the MORB fields, overlapping with island-arc volcanics from the Marianas and Tonga. Compared with MORB and ocean-island basalts, the samples show alkali-element enrichment relative to REE and higher Cs relative to Rb. The isotopic and geochemical characteristics of the Valu Fa Ridge volcanics clearly indicate a minor, but significant, slab-derived component in the back-arc basin mantle source.",
author = "Jenner, {G. A.} and Cawood, {P. A.} and M. Rautenschlein and White, {W. M.}",
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Composition of back-arc basin volcanics, Valu Fa Ridge, Lau Basin : Evidence for a slab-derived component in their mantle source. / Jenner, G. A.; Cawood, P. A.; Rautenschlein, M.; White, W. M.

In: Journal of Volcanology and Geothermal Research, Vol. 32, No. 1-3, 01.01.1987, p. 209-222.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Composition of back-arc basin volcanics, Valu Fa Ridge, Lau Basin

T2 - Evidence for a slab-derived component in their mantle source

AU - Jenner, G. A.

AU - Cawood, P. A.

AU - Rautenschlein, M.

AU - White, W. M.

PY - 1987/1/1

Y1 - 1987/1/1

N2 - Samples dredged from 2 localities near the crest of the Valu Fa ridge, an active back-arc basin spreading centre in the Lau Basin, consist of highly vesicular lava fragments of andesitic composition. The samples are characterized by rare, euhedral An85 plagioclase phenocrysts in a hypocrystalline groundmass of An60 plagioclase laths, brown glass and rare subhedral clinopyroxene. Samples from within and, to a lesser extent, between the dredge hauls show remarkable isotopic and chemical homogeneity, with: 87Sr/86Sr - 0.70330 ± 2; 143Nd/144Nd - 0.51303 ± 2; 206Pb/204Pb - 18.65 ± 2; 207Pb/204Pb - 15.55 ± 1; 208Pb/204Pb - 38.34 ± 4; Sr - 165 ppm; Rb - 7 ppm; Cs - 0.17 ppm; K - 3300 to 4200 ppm; Ba - 96 ppm; and REE - LREE depleted with 12-18 × chondritic abundances. On Sr-Nd, Pb-Pb and Sr-Pb plots the volcanics lie just within or on the edge of the MORB fields, overlapping with island-arc volcanics from the Marianas and Tonga. Compared with MORB and ocean-island basalts, the samples show alkali-element enrichment relative to REE and higher Cs relative to Rb. The isotopic and geochemical characteristics of the Valu Fa Ridge volcanics clearly indicate a minor, but significant, slab-derived component in the back-arc basin mantle source.

AB - Samples dredged from 2 localities near the crest of the Valu Fa ridge, an active back-arc basin spreading centre in the Lau Basin, consist of highly vesicular lava fragments of andesitic composition. The samples are characterized by rare, euhedral An85 plagioclase phenocrysts in a hypocrystalline groundmass of An60 plagioclase laths, brown glass and rare subhedral clinopyroxene. Samples from within and, to a lesser extent, between the dredge hauls show remarkable isotopic and chemical homogeneity, with: 87Sr/86Sr - 0.70330 ± 2; 143Nd/144Nd - 0.51303 ± 2; 206Pb/204Pb - 18.65 ± 2; 207Pb/204Pb - 15.55 ± 1; 208Pb/204Pb - 38.34 ± 4; Sr - 165 ppm; Rb - 7 ppm; Cs - 0.17 ppm; K - 3300 to 4200 ppm; Ba - 96 ppm; and REE - LREE depleted with 12-18 × chondritic abundances. On Sr-Nd, Pb-Pb and Sr-Pb plots the volcanics lie just within or on the edge of the MORB fields, overlapping with island-arc volcanics from the Marianas and Tonga. Compared with MORB and ocean-island basalts, the samples show alkali-element enrichment relative to REE and higher Cs relative to Rb. The isotopic and geochemical characteristics of the Valu Fa Ridge volcanics clearly indicate a minor, but significant, slab-derived component in the back-arc basin mantle source.

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U2 - 10.1016/0377-0273(87)90045-X

DO - 10.1016/0377-0273(87)90045-X

M3 - Article

VL - 32

SP - 209

EP - 222

JO - Journal of Volcanology and Geothermal Research

JF - Journal of Volcanology and Geothermal Research

SN - 0377-0273

IS - 1-3

ER -