Shervais, John W; Reagan, Mark K; Godard, Marguerite; Prytulak, Julie; Ryan, Jeffrey G; Pearce, Julian A; Almeev, Renat R; Li, Hongyan; Haugen, Emily; Chapman, Timothy; Kurz, Walter; Nelson, Wendy R; Heaton, Daniel E; Kirchenbaur, Maria; Shimizu, Kenji; Sakuyama, Tetsuya; Vetter, Scott K; Li, Yibing; Whattam, Scott

Author(s)

Shervais, John W

Reagan, Mark K

Godard, Marguerite

Prytulak, Julie

Ryan, Jeffrey G

Pearce, Julian A

Almeev, Renat R

Li, Hongyan

Haugen, Emily

Chapman, Timothy

Kurz, Walter

Nelson, Wendy R

Heaton, Daniel E

Kirchenbaur, Maria

Shimizu, Kenji

Sakuyama, Tetsuya

Vetter, Scott K

Li, Yibing

Whattam, Scott

Publication Date

2021-01

Abstract

This article is a companion to Coulthard et al. (2020), <a href="https://doi.org/10.1029/2020GC009054">https://doi.org/10.1029/2020GC009054</a>.

Abstract

International Ocean Discovery Program Expedition 352 to the Izu-Bonin forearc cored over 800 m of basement comprising boninite and boninite-series lavas. This is the most extensive, well-constrained suite of boninite series lavas ever obtained from in situ oceanic crust. The boninites are characterized as high-silica boninite (HSB), low-silica boninite (LSB), or basaltic boninite based on their SiO<sub>2</sub>-MgO-TiO<sub>2</sub> relations. The principal fractionation products of all three series are high-Mg andesites (HMA). Lavas recovered >250 meters below seafloor (mbsf) erupted at a forearc spreading axis and are dominated by LSB and HMA. Lavas recovered from <250 mbsf erupted off-axis and are dominated by HSB. The axial and off-axis lavas are characterized by distinct chemostratigraphic trends in their major, trace, and isotopic compositions. The off-axis lavas are chemically similar to boninite from the type locality at Chichijima, with concave-upward rare earth elements patterns. In contrast, the more abundant axial lavas have distinctly light rare earth element-depleted patterns and represent a new, previously unsampled precursor to the Chichijima-type boninite lavas. Petrogenetic modeling suggests that the axial lavas formed by fluxing of refractory mantle (likely the residue from forearc basalt extraction), with amphibolite-facies melt derived from subducting altered oceanic crust. The upper, off-axis lavas require an additional component of sediment-derived melt in addition. Both models are consistent with previously published isotopic data.

Citation

Geochemistry, Geophysics, Geosystems, 22(1), p. 1-34

ISSN

1525-2027

Link

https://hdl.handle.net/1959.11/30370

Publisher

Wiley-Blackwell Publishing, Inc

Title

Magmatic Response to Subduction Initiation, Part II: Boninites and Related Rocks of the Izu‐Bonin Arc From IOPD Expedition 352

Type of document

Journal Article

Entity Type

Publication

Author(s)	Shervais, John W Reagan, Mark K Godard, Marguerite Prytulak, Julie Ryan, Jeffrey G Pearce, Julian A Almeev, Renat R Li, Hongyan Haugen, Emily Chapman, Timothy Kurz, Walter Nelson, Wendy R Heaton, Daniel E Kirchenbaur, Maria Shimizu, Kenji Sakuyama, Tetsuya Vetter, Scott K Li, Yibing Whattam, Scott
Publication Date	2021-01
Abstract	This article is a companion to Coulthard et al. (2020), <a href="https://doi.org/10.1029/2020GC009054">https://doi.org/10.1029/2020GC009054</a>.
Abstract	International Ocean Discovery Program Expedition 352 to the Izu-Bonin forearc cored over 800 m of basement comprising boninite and boninite-series lavas. This is the most extensive, well-constrained suite of boninite series lavas ever obtained from in situ oceanic crust. The boninites are characterized as high-silica boninite (HSB), low-silica boninite (LSB), or basaltic boninite based on their SiO<sub>2</sub>-MgO-TiO<sub>2</sub> relations. The principal fractionation products of all three series are high-Mg andesites (HMA). Lavas recovered >250 meters below seafloor (mbsf) erupted at a forearc spreading axis and are dominated by LSB and HMA. Lavas recovered from <250 mbsf erupted off-axis and are dominated by HSB. The axial and off-axis lavas are characterized by distinct chemostratigraphic trends in their major, trace, and isotopic compositions. The off-axis lavas are chemically similar to boninite from the type locality at Chichijima, with concave-upward rare earth elements patterns. In contrast, the more abundant axial lavas have distinctly light rare earth element-depleted patterns and represent a new, previously unsampled precursor to the Chichijima-type boninite lavas. Petrogenetic modeling suggests that the axial lavas formed by fluxing of refractory mantle (likely the residue from forearc basalt extraction), with amphibolite-facies melt derived from subducting altered oceanic crust. The upper, off-axis lavas require an additional component of sediment-derived melt in addition. Both models are consistent with previously published isotopic data.
Citation	Geochemistry, Geophysics, Geosystems, 22(1), p. 1-34
ISSN	1525-2027
Link	https://hdl.handle.net/1959.11/30370
Publisher	Wiley-Blackwell Publishing, Inc
Title	Magmatic Response to Subduction Initiation, Part II: Boninites and Related Rocks of the Izu‐Bonin Arc From IOPD Expedition 352
Type of document	Journal Article
Entity Type	Publication

Magmatic Response to Subduction Initiation, Part II: Boninites and Related Rocks of the Izu‐Bonin Arc From IOPD Expedition 352

Files: