Journal article
Magmatic Response to Subduction Initiation: Part 1. Fore-arc Basalts of the Izu-Bonin Arc From IODP Expedition 352
Geochemistry, Geophysics, Geosystems, Vol.20(1), pp.314-338
01/2019
DOI: 10.1029/2018GC007731
PMCID: PMC6392113
PMID: 30853858
Abstract
The Izu‐Bonin‐Mariana (IBM) fore arc preserves igneous rock assemblages that formed during subduction initiation circa 52 Ma. International Ocean Discovery Program (IODP) Expedition 352 cored four sites in the fore arc near the Ogasawara Plateau in order to document the magmatic response to subduction initiation and the physical, petrologic, and chemical stratigraphy of a nascent subduction zone. Two of these sites (U1440 and U1441) are underlain by fore‐arc basalt (FAB). FABs have mid‐ocean ridge basalt (MORB)‐like compositions, however, FAB are consistently lower in the high‐field strength elements (TiO2, P2O5, Zr) and Ni compared to MORB, with Na2O at the low end of the MORB field and FeO* at the high end. Almost all FABs are light rare earth element depleted, with low total REE, and have low ratios of highly incompatible to less incompatible elements (Ti/V, Zr/Y, Ce/Yb, and Zr/Sm) relative to MORB. Chemostratigraphic trends in Hole U1440B are consistent with the uppermost lavas forming off axis, whereas the lower lavas formed beneath a spreading center axis. Axial magma of U1440B becomes more fractionated upsection; overlying off‐axis magmas return to more primitive compositions. Melt models require a two‐stage process, with early garnet field melts extracted prior to later spinel field melts, with up to 23% melting to form the most depleted compositions. Mantle equilibration temperatures are higher than normal MORB (1,400 °C–1,480 °C) at relatively low pressures (1–2 GPa), which may reflect an influence of the Manus plume during subduction initiation. Our data support previous models of FAB origin by decompression melting but imply a source more depleted than normal MORB source mantle.
Details
- Title: Subtitle
- Magmatic Response to Subduction Initiation: Part 1. Fore-arc Basalts of the Izu-Bonin Arc From IODP Expedition 352
- Creators
- John Shervais - Utah State UniversityMark Reagan - University of Iowa [Iowa City]Emily Haugen - Utah State UniversityRenat Almeev - Institut für Mineralogie [Hannover]Julian Pearce - Cardiff UniversityJulie Prytulak - Department of Earth Science and Engineering [Imperial College London]Jeffrey Ryan - University of South FloridaScott Whattam - King Fahad UniversityMarguerite Godard - Géosciences MontpellierTimothy Chapman - The University of SydneyHongyan Li - Chinese Academy of Geological Sciences [Beijing]Walter Kurz - University of GrazWendy Nelson - Towson University [Towson, MD, United States]Daniel Heaton - Oregon State UniversityMaria Kirchenbaur - Universität zu KölnKenji Shimizu - Japan Agency for Marine-Earth Science and TechnologyTetsuya Sakuyama - Osaka University [Osaka]Yibing Li - Chinese Academy of Geological SciencesScott Vetter - Centenary college Shreveport
- Contributors
- Gm Aigle (Editor)
- Resource Type
- Journal article
- Publication Details
- Geochemistry, Geophysics, Geosystems, Vol.20(1), pp.314-338
- DOI
- 10.1029/2018GC007731
- PMID
- 30853858
- PMCID
- PMC6392113
- NLM abbreviation
- Geochem Geophys Geosyst
- ISSN
- 1525-2027
- eISSN
- 1525-2027
- Publisher
- AGU and the Geochemical Society
- Grant note
- DOI: 10.13039/501100002428, name: Austrian Science Fund, award: P27982‐N29; DOI: 10.13039/501100001659, name: Deutsche Forschungsgemeinschaft, award: AL1189/8‐; DOI: 10.13039/501100000270, name: Natural Environment Research Council, award: NE/M012034/, NE/M010643/1; DOI: 10.13039/100000001, name: National Science Foundation, award: 1558689
- Language
- English
- Date published
- 01/2019
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9983983668202771
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