The arc arises; the links between volcanic output, arc evolution and melt composition

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doi: 10.1016/j.epsl.2016.12.027
Author(s): Brandl, Philipp A.; Hamada, Morihisa; Arculus, Richard J.; Johnson, Kyle; Marsaglia, Kathleen M.; Savov, Ivan P.; Ishizuka, Osamu; Li, He
Author Affiliation(s): Primary:
GEOMAR-Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
Other:
Japan Agency for Marine-Earth Science and Technology, Japan
Australian National University, Australia
California State University Northridge, United States
University of Leeds, United Kingdom
Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, China
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, Vol.461, p.73-84. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Includes appendix. 64 refs.; illus., incl. sketch map
Summary: Subduction initiation is a key process for global plate tectonics. Individual lithologies developed during subduction initiation and arc inception have been identified in the trench wall of the Izu-Bonin-Mariana (IBM) island arc but a continuous record of this process has not previously been described. Here, we present results from International Ocean Discovery Program Expedition 351 that drilled a single site west of the Kyushu-Palau Ridge (KPR), a chain of extinct stratovolcanoes that represents the proto-IBM island arc, active for ∼25 Ma following subduction initiation. Site U1438 recovered 150 m of oceanic igneous basement and ∼1450 m of overlying sediments. The lower 1300 m of these sediments comprise volcaniclastic gravity-flow deposits shed from the evolving KPR arc front. We separated fresh magmatic minerals from Site U1438 sediments, and analyzed 304 glass (formerly melt) inclusions, hosted by clinopyroxene and plagioclase. Compositions of glass inclusions preserve a temporal magmatic record of the juvenile island arc, complementary to the predominant mid-Miocene to recent activity determined from tephra layers recovered by drilling in the IBM forearc. The glass inclusions record the progressive transition of melt compositions dominated by an early 'calc-alkalic', high-Mg andesitic stage to a younger tholeiitic stage over a time period of 11 Ma. High-precision trace element analytical data record a simultaneously increasing influence of a deep subduction component (e.g., increase in Th vs. Nb, light rare earth element enrichment) and a more fertile mantle source (reflected in increased high field strength element abundances). This compositional change is accompanied by increased deposition rates of volcaniclastic sediments reflecting magmatic output and maturity of the arc. We conclude the 'calc-alkalic' stage of arc evolution may endure as long as mantle wedge sources are not mostly advected away from the zones of arc magma generation, or the rate of wedge replenishment by corner flow does not overwhelm the rate of magma extraction.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Basalts; Calc-alkalic composition; Composition; Expedition 351; Fluid inclusions; Gravity flows; IODP Site U1438; Igneous rocks; Inclusions; International Ocean Discovery Program; Island arcs; Izu-Bonin Arc; Kyushu-Palau Ridge; Magmas; Magmatism; Mantle wedges; Mariana Islands; Melt inclusions; Melts; Micronesia; North Pacific; Northwest Pacific; Oceania; Pacific Ocean; Philippine Sea; Subduction; Tholeiite; Trace elements; Volcanic rocks; Volcaniclastics; West Pacific
Coordinates: N272300 N272301 E1341907 E1341905
Record ID: 2017025678
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands