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

Brandl, Philipp A., Hamada, M., Arculus, R. J., Johnson, K., Marsaglia, K. M., Savov, I. P., Ishizuka, O. and Li, H. (2017) The arc arises: The links between volcanic output, arc evolution and melt composition Earth and Planetary Science Letters, 461 . pp. 73-84. DOI 10.1016/j.epsl.2016.12.027.

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Supplementary data:

Abstract

Highlights

• Glass inclusions record 11 Ma of early arc magma evolution.
• Arc tholeiites succeed calc-alkalic magmas temporally.
• Volcanic arc output directly linked to mantle wedge composition.
• Dynamic slab control on arc magmatism following subduction initiation.

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.

Document Type: Article
Keywords: Izu–Bonin; U1438; mantle wedge; subduction; island arc; melt inclusion; IODP Exp.351
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems > Marine Mineralische Rohstoffe
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1016/j.epsl.2016.12.027
ISSN: 0012-821X
Projects: Future Ocean
Expeditions/Models:
Date Deposited: 12 Jan 2017 11:09
Last Modified: 10 May 2017 11:21
URI: http://eprints.uni-kiel.de/id/eprint/35615

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