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Two mantle domains and the time scales of fluid transfer beneath the Vanuatu Arc

Simon P. Turner, David W. Peate, Chris J. Hawkesworth, Stephen M. Eggins and Anthony J. Crawford
Two mantle domains and the time scales of fluid transfer beneath the Vanuatu Arc
Geology (Boulder) (November 1999) 27 (11): 963-966

Abstract

U-Th isotope disequilibria can provide constraints on the time elapsed since fluid addition to the mantle wedge beneath island arcs. The Vanuatu arc offers new insights into these processes because Pb isotopes there are not dominated by components from the subducting plate and so preserve the signatures of the mantle wedge. The Pb isotope data document the presence of separate Pacific and Indian mantle domains beneath the arc volcanoes. The Indian mantle was brought beneath the central part of the arc from the backarc by collision with the D'Entrecasteaux Ridge, resulting in a slowing of subduction there. The distinction in the mantle wedge composition is also uniquely apparent in U-Th isotope data, which define two subparallel arrays on the U-Th equiline diagram, one anchored to high U/Th Pacific mantle and the other to lower U/Th Indian mantle. These data provide clear evidence of the effects of variable mantle composition on U-Th isotope disequilibria. We argue that such arrays faithfully record the time elapsed since fluid release from the subducting plate. The data indicate that this occurred ca. 16 ka in the area of collision and slow subduction, but ca. 60 ka where the rate of subduction is substantially faster. This suggests a link between the rate of subduction and the time elapsed since fluid release.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 27
Serial Issue: 11
Title: Two mantle domains and the time scales of fluid transfer beneath the Vanuatu Arc
Affiliation: Open University, Department of Earth Sciences, Milton Keynes, United Kingdom
Pages: 963-966
Published: 199911
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 21
Accession Number: 1999-070120
Categories: Isotope geochemistrySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch map
S20°30'00" - S13°00'00", E166°00'00" - E169°00'00"
Secondary Affiliation: Danish Lithosphere Centre, Copenhagen, DNK, DenmarkAustralian National University, Canberra, AUS, AustraliaUniversity of Tasmania, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199924
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