Details
| Original language | English |
|---|---|
| Pages (from-to) | 314-338 |
| Number of pages | 25 |
| Journal | Geochemistry, Geophysics, Geosystems |
| Volume | 20 |
| Issue number | 1 |
| Early online date | 18 Dec 2018 |
| Publication status | Published - 13 Feb 2019 |
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 (TiO 2 , P 2 O 5 , Zr) and Ni compared to MORB, with Na 2 O 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.
Keywords
- Forearc basalts, Izu-Bonin forearc, Joides Resolution, ophiolites, subduction initiation
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Geochemistry, Geophysics, Geosystems, Vol. 20, No. 1, 13.02.2019, p. 314-338.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Magmatic Response to Subduction Initiation
T2 - Part 1. Fore-arc Basalts of the Izu-Bonin Arc From IODP Expedition 352
AU - Shervais, John W.
AU - Reagan, Mark
AU - Haugen, Emily
AU - Almeev, Renat R.
AU - Pearce, Julian A.
AU - Prytulak, Julie
AU - Ryan, Jeffrey G.
AU - Whattam, Scott A.
AU - Godard, Marguerite
AU - Chapman, Timothy
AU - Li, Hongyan
AU - Kurz, Walter
AU - Nelson, Wendy R.
AU - Heaton, Daniel
AU - Kirchenbaur, Maria
AU - Shimizu, Kenji
AU - Sakuyama, Tetsuya
AU - Li, Yibing
AU - Vetter, Scott K.
N1 - Funding information: This research used samples and/or data provided by the International Ocean Discovery Program (IODP). The authors are grateful for support from IODP, the JOIDES Resolution Facility, and the scientific staff and crew aboard the JOIDES Resolution during Expedition 352. Funding support to U.S. participants (J. W. S., M. K. R., J. G. R., and W. N.) from the Consortium for Ocean Leadership and from the National Science Foundation is gratefully acknowledged (OCE-1558689 to Shervais, OCE-1558647 to Reagan, OCE-1558855 to Ryan, and OCE-1558608 to Nelson). Prytulak was supported by NERC directed grant NE/M010643/1. Chapman was supported by the Australia-New Zealand IODP consortium and the ARC LIEF scheme (LE140100047). Almeev was supported by R. A. by the German Science Foundation (DFG, Project AL1189/8-1). Pearce was supported by NERC (UK) grant (NE/M012034/1). Kurz appreciates support by the Austrian Academy of Sciences and funding by the Austrian Science Fund (FWF Project P27982-N29). Kirchenbaur appreciates funding by the German IODP consortium and the BGR Germany. Reviews by Marcel Regelous, Gene M. Yogodzinski, and two anonymous reviewers are gratefully acknowledged. Supporting information table is archived at PANGAEA Data Archiving and Publication (PDI-18813) (https://doi.pangaea.de/10.1594/PANGAEA.895122). This research used samples and/or data provided by the International Ocean Discovery Program (IODP). The authors are grateful for support from IODP, the JOIDES Resolution Facility, and the scientific staff and crew aboard the JOIDES Resolution during Expedition 352. Funding support to U. S. participants (J. W. S., M. K. R., J. G. R., and W. N.) from the Consortium for Ocean Leadership and from the National Science Foundation is gratefully acknowledged (OCE-1558689 to Shervais, OCE-1558647 to Reagan, OCE-1558855 to Ryan, and OCE-1558608 to Nelson). Prytulak was supported by NERC directed grant NE/M010643/1. Chapman was supported by the Australia-New Zealand IODP consortium and the ARC LIEF scheme (LE140100047). Almeev was supported by R. A. by the German Science Foundation (DFG, Project AL1189/8-1). Pearce was supported by NERC (UK) grant (NE/M012034/1). Kurz appreciates support by the Austrian Academy of Sciences and funding by the Austrian Science Fund (FWF Project P27982-N29). Kirchenbaur appreciates funding by the German IODP consortium and the BGR Germany. Reviews by Marcel Regelous, Gene M. Yogodzinski, and two anon ymous reviewers are gratefully acknowledged. Supporting information table is archived at PANGAEA Data Archiving and Publication (PDI-18813) (https://doi.pangaea.de/10.1594/ PANGAEA.895122).
PY - 2019/2/13
Y1 - 2019/2/13
N2 - 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 (TiO 2 , P 2 O 5 , Zr) and Ni compared to MORB, with Na 2 O 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.
AB - 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 (TiO 2 , P 2 O 5 , Zr) and Ni compared to MORB, with Na 2 O 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.
KW - Forearc basalts
KW - Izu-Bonin forearc
KW - Joides Resolution
KW - ophiolites
KW - subduction initiation
UR - http://www.scopus.com/inward/record.url?scp=85060149224&partnerID=8YFLogxK
U2 - 10.1029/2018GC007731
DO - 10.1029/2018GC007731
M3 - Article
AN - SCOPUS:85060149224
VL - 20
SP - 314
EP - 338
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
SN - 1525-2027
IS - 1
ER -