Universität zu Köln

Shervais, John W., Reagan, Mark ORCID: 0000-0003-1628-4194, Haugen, Emily ORCID: 0000-0002-0263-9911, Almeev, Renat R., Pearce, Julian A., Prytulak, Julie, Ryan, Jeffrey G., Whattam, Scott A., Godard, Marguerite ORCID: 0000-0003-3097-5135, Chapman, Timothy ORCID: 0000-0002-4821-6420, Li, Hongyan, Kurz, Walter, Nelson, Wendy R., Heaton, Daniel, Kirchenbaur, Maria, Shimizu, Kenji, Sakuyama, Tetsuya, Li, Yibing and Vetter, Scott K. (2019). Magmatic Response to Subduction Initiation: Part 1. Fore-arc Basalts of the Izu-Bonin Arc From IODP Expedition 352. Geochem. Geophys. Geosyst., 20 (1). S. 314 - 339. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 1525-2027

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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 degrees C-1,480 degrees 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.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Shervais, John W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Reagan, Mark UNSPECIFIED orcid.org/0000-0003-1628-4194 UNSPECIFIED Haugen, Emily UNSPECIFIED orcid.org/0000-0002-0263-9911 UNSPECIFIED Almeev, Renat R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Pearce, Julian A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Prytulak, Julie UNSPECIFIED UNSPECIFIED UNSPECIFIED Ryan, Jeffrey G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Whattam, Scott A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Godard, Marguerite UNSPECIFIED orcid.org/0000-0003-3097-5135 UNSPECIFIED Chapman, Timothy UNSPECIFIED orcid.org/0000-0002-4821-6420 UNSPECIFIED Li, Hongyan UNSPECIFIED UNSPECIFIED UNSPECIFIED Kurz, Walter UNSPECIFIED UNSPECIFIED UNSPECIFIED Nelson, Wendy R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Heaton, Daniel UNSPECIFIED UNSPECIFIED UNSPECIFIED Kirchenbaur, Maria UNSPECIFIED UNSPECIFIED UNSPECIFIED Shimizu, Kenji UNSPECIFIED UNSPECIFIED UNSPECIFIED Sakuyama, Tetsuya UNSPECIFIED UNSPECIFIED UNSPECIFIED Li, Yibing UNSPECIFIED UNSPECIFIED UNSPECIFIED Vetter, Scott K. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-139682
DOI:	10.1029/2018GC007731
Journal or Publication Title:	Geochem. Geophys. Geosyst.
Volume:	20
Number:	1
Page Range:	S. 314 - 339
Date:	2019
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	1525-2027
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WEST PHILIPPINE BASIN; SNAKE RIVER PLAIN; PARECE VELA BASIN; SEA PLATE; FRANCISCAN SUBDUCTION; MANTLE HETEROGENEITY; ISOTOPIC SIGNATURE; MIDOCEAN RIDGE; BACKARC BASIN; EARLY HISTORY Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/13968