Abstract
Knowledge of the lithological variability and genesis of island arc crust is important for understanding continental growth. Although the volcanic architecture of island arcs is comparatively well known, the nature of island arc middle- and lower-crust remains uncertain owing to limited exposure. One of the best targets for deciphering the evolution of an island arc system is the Tanzawa Tonalites (4-9Ma), in the intra-oceanic Izu-Bonin-Mariana arc. These tonalities which occupied a mid-crustal position were generated by partial melting of lower crust. To constrain protoliths of the plutonic rocks in the island arc lower crust, in-situ O-isotopic analysis using an IMS-1280 Secondary Ion Mass Spectrometer was carried out on 202 zircon grains separated from 4 plutons in the Tanzawa Tonalite. δ18O value of the zircons ranges from 4.1‰ to 5.5‰ and some zircons have δ18O slightly lower than the mantle range. The low zircon δ18O values from the Tanzawa Tonalite suggest that their protoliths involved materials with lower δ18O values than those of the mantle. Hydrothermally altered gabbros in the lower oceanic crust often have lower δ18O values than mantle and can be primary components of arc lower crust. The Tanzawa Tonalite is interpreted to have been formed by partial melting of island arc lower crust. Thus the low δ18O values in zircons from the Tanzawa Tonalites may originate by melting of the hydrothermally altered gabbro. Ancient oceanic crustal material was likely present in the Izu-Bonin-Mariana arc lower crust, at the time of formation of the Tanzawa Tonalites.
| Original language | English |
|---|---|
| Pages (from-to) | 43-54 |
| Number of pages | 12 |
| Journal | Lithos |
| Volume | 228-229 |
| DOIs | |
| Publication status | Published - Jul 1 2015 |
| Externally published | Yes |
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Keywords
- Arc lower-crust
- IBM arc
- Oceanic crust
- Tanzawa Tonalitic Pluton
- Zircon oxygen isotope
ASJC Scopus subject areas
- Geochemistry and Petrology
Cite this
Ancient oceanic crust in island arc lower crust : Evidence from oxygen isotopes in zircons from the Tanzawa Tonalitic Pluton. / Suzuki, Kazue; Kitajima, Kouki; Sawaki, Yusuke; Hattori, Kentaro; Hirata, Takafumi; Maruyama, Shigenori.
In: Lithos, Vol. 228-229, 01.07.2015, p. 43-54.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Ancient oceanic crust in island arc lower crust
T2 - Evidence from oxygen isotopes in zircons from the Tanzawa Tonalitic Pluton
AU - Suzuki, Kazue
AU - Kitajima, Kouki
AU - Sawaki, Yusuke
AU - Hattori, Kentaro
AU - Hirata, Takafumi
AU - Maruyama, Shigenori
PY - 2015/7/1
Y1 - 2015/7/1
N2 - Knowledge of the lithological variability and genesis of island arc crust is important for understanding continental growth. Although the volcanic architecture of island arcs is comparatively well known, the nature of island arc middle- and lower-crust remains uncertain owing to limited exposure. One of the best targets for deciphering the evolution of an island arc system is the Tanzawa Tonalites (4-9Ma), in the intra-oceanic Izu-Bonin-Mariana arc. These tonalities which occupied a mid-crustal position were generated by partial melting of lower crust. To constrain protoliths of the plutonic rocks in the island arc lower crust, in-situ O-isotopic analysis using an IMS-1280 Secondary Ion Mass Spectrometer was carried out on 202 zircon grains separated from 4 plutons in the Tanzawa Tonalite. δ18O value of the zircons ranges from 4.1‰ to 5.5‰ and some zircons have δ18O slightly lower than the mantle range. The low zircon δ18O values from the Tanzawa Tonalite suggest that their protoliths involved materials with lower δ18O values than those of the mantle. Hydrothermally altered gabbros in the lower oceanic crust often have lower δ18O values than mantle and can be primary components of arc lower crust. The Tanzawa Tonalite is interpreted to have been formed by partial melting of island arc lower crust. Thus the low δ18O values in zircons from the Tanzawa Tonalites may originate by melting of the hydrothermally altered gabbro. Ancient oceanic crustal material was likely present in the Izu-Bonin-Mariana arc lower crust, at the time of formation of the Tanzawa Tonalites.
AB - Knowledge of the lithological variability and genesis of island arc crust is important for understanding continental growth. Although the volcanic architecture of island arcs is comparatively well known, the nature of island arc middle- and lower-crust remains uncertain owing to limited exposure. One of the best targets for deciphering the evolution of an island arc system is the Tanzawa Tonalites (4-9Ma), in the intra-oceanic Izu-Bonin-Mariana arc. These tonalities which occupied a mid-crustal position were generated by partial melting of lower crust. To constrain protoliths of the plutonic rocks in the island arc lower crust, in-situ O-isotopic analysis using an IMS-1280 Secondary Ion Mass Spectrometer was carried out on 202 zircon grains separated from 4 plutons in the Tanzawa Tonalite. δ18O value of the zircons ranges from 4.1‰ to 5.5‰ and some zircons have δ18O slightly lower than the mantle range. The low zircon δ18O values from the Tanzawa Tonalite suggest that their protoliths involved materials with lower δ18O values than those of the mantle. Hydrothermally altered gabbros in the lower oceanic crust often have lower δ18O values than mantle and can be primary components of arc lower crust. The Tanzawa Tonalite is interpreted to have been formed by partial melting of island arc lower crust. Thus the low δ18O values in zircons from the Tanzawa Tonalites may originate by melting of the hydrothermally altered gabbro. Ancient oceanic crustal material was likely present in the Izu-Bonin-Mariana arc lower crust, at the time of formation of the Tanzawa Tonalites.
KW - Arc lower-crust
KW - IBM arc
KW - Oceanic crust
KW - Tanzawa Tonalitic Pluton
KW - Zircon oxygen isotope
UR - http://www.scopus.com/inward/record.url?scp=84929353659&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84929353659&partnerID=8YFLogxK
U2 - 10.1016/j.lithos.2015.04.005
DO - 10.1016/j.lithos.2015.04.005
M3 - Article
AN - SCOPUS:84929353659
VL - 228-229
SP - 43
EP - 54
JO - Lithos
JF - Lithos
SN - 0024-4937
ER -