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Titolo:
Across-arc geochemical trends in the Izu-Bonin arc: Contributions from thesubducting slab
Autore:
Hochstaedter, A; Gill, J; Peters, R; Broughton, P; Holden, P; Taylor, B;
Indirizzi:
Univ Calif Santa Cruz, Dept Earth Sci, Santa Cruz, CA 95064 USA Univ CalifSanta Cruz Santa Cruz CA USA 95064 i, Santa Cruz, CA 95064 USA Univ Hawaii, Sch Ocean & Earth Sci & Technol, Honolulu, HI 96822 USA Univ Hawaii Honolulu HI USA 96822 h Sci & Technol, Honolulu, HI 96822 USA
Titolo Testata:
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
, volume: 2, anno: 2001,
pagine: NIL_9 - NIL_52
SICI:
1525-2027(20010702)2:<NIL_9:AGTITI>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
CONVERGENT-MARGIN MAGMAS; KERMADEC ISLAND-ARC; TRACE-ELEMENT; SUMISU RIFT; ISOTOPIC CHARACTERISTICS; PHILIPPINE SEA; OGASAWARA ARC; MANTLE; CONSTRAINTS; VOLCANISM;
Keywords:
trace element geochemistry; Izu-Bonin arc; Island arc; volcanic arc; isotope geochemistry;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Hochstaedter, A Univ Calif Santa Cruz, Dept Earth Sci, Santa Cruz, CA 95064 USA Univ Calif Santa Cruz Santa Cruz CA USA 95064 A 95064 USA
Citazione:
A. Hochstaedter et al., "Across-arc geochemical trends in the Izu-Bonin arc: Contributions from thesubducting slab", GEOCH GEO G, 2, 2001, pp. NIL_9-NIL_52

Abstract

We propose that across-arc differences in the geochemistry of Izu-Bonin arc magmas are controlled by the addition of fertile-slab fluids to depleted mantle at the volcanic front, and residual-slab fluids to fertile mantle inthe back arc without slab melting or contemporaneous back arc spreading. The arc consists of a volcanic front, an extensional zone, and seamount chains ( the Western Seamounts) that trend into the Shikoku Basin. Each province produces a distinct suite of arc-like volcanic rocks that have relative Nb depletions and high ratios of fluid-mobile elements to high field strength elements. The volcanic front has the lowest concentrations of incompatible elements and the strongest relative enrichments of fluid-mobile elements ( high U/Nb, Ba/Nb, Pb/Zr, Th/Nb, Pb-206/Pb-204, epsilon (Nd), and Sr-87/Sr-86). A fluid derived from both sediment and altered oceanic crust explainsmost of the slab-related characteristics of the volcanic front. The Western Seamounts and some of the extensional zone rocks have lower epsilon (Nd),Sr-87/Sr-86, Pb-206/Pb-204, Ba/Th, and U/Th; moderate Ba/Nb and U/Nb; and similar or higher Th/Nb and Th/Nd. Although the lower epsilon (Nd) and higher Th/Nd tempt a sediment melt explanation, a lack of correlation between the strongest sediment proxies, such as epsilon (Nd), Th/Nb, and Ce/Ce*, precludes sediment melts. The subduction component for the Western Seamounts is probably a fluid dehydrated from a residual slab that was depleted in fluid-mobile elements beneath ( as well as trenchward of) the volcanic front. This depleted fluid is added to elementally and isotopically more enriched mantle beneath the Western Seamounts.

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Documento generato il 04/04/20 alle ore 02:46:18