抄録
Boninites are widely distributed along the western margin of the Pacific Plate extruded during the incipient stage of the subduction zone development in the early Paleogene period. This paper discusses the genetic relationships of boninite and antecedent protoarc basalt magmas and demonstrates their recycled ancient slab origin based on the T–P conditions and Pb–Hf–Nd–Os isotopic modeling. Primitive melt inclusions in chrome spinel from Ogasawara and Guam islands show severely depleted high-SiO2, MgO (high-silica) and less depleted low-SiO2, MgO (low-silica and ultralow-silica) boninitic compositions. The genetic conditions of 1 346 °C at 0.58 GPa and 1 292 °C at 0.69 GPa for the low- and ultralow-silica boninite magmas lie on adiabatic melting paths of depleted mid-ocean ridge basalt mantle with a potential temperature of 1 430 °C in Ogasawara and of 1 370 °C in Guam, respectively. This is consistent with the model that the low- and ultralow-silica boninites were produced by remelting of the residue of the protoarc basalt during the forearc spreading immediately following the subduction initiation. In contrast, the genetic conditions of 1 428 °C and 0.96 GPa for the high-silica boninite magma is reconciled with the ascent of more depleted harzburgitic source which pre-existed below the Izu–Ogasawara–Mariana forearc region before the subduction started. Mixing calculations based on the Pb–Nd–Hf isotopic data for the Mariana protoarc basalt and boninites support the above remelting model for the (ultra)low-silica boninite and the discrete harzburgite source for the high-silica boninite. Yb–Os isotopic modeling of the high-Si boninite source indicates 18–30 wt% melting of the primitive upper mantle at 1.5–1.7 Ga, whereas the source mantle of the protoarc basalt, the residue of which became the source of the (ultra)low-Si boninite, experienced only 3.5–4.0 wt% melt depletion at 3.6–3.1 Ga, much earlier than the average depleted mid-ocean ridge basalt mantle with similar degrees of melt depletion at 2.6–2.2 Ga.
| 元の言語 | 英語 |
|---|---|
| 記事番号 | e12221 |
| ジャーナル | Island Arc |
| 巻 | 27 |
| 発行部数 | 1 |
| DOI | |
| 出版物ステータス | 出版済み - 1 2018 |
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All Science Journal Classification (ASJC) codes
- Geology
これを引用
Did boninite originate from the heterogeneous mantle with recycled ancient slab? / Umino, Susumu; Kanayama, Kyoko; Kitamura, Keitaro; Tamura, Akihiro; Ishizuka, Osamu; Senda, Ryoko; Arai, Shoji.
：: Island Arc, 巻 27, 番号 1, e12221, 01.2018.研究成果: ジャーナルへの寄稿 › 記事
}
TY - JOUR
T1 - Did boninite originate from the heterogeneous mantle with recycled ancient slab?
AU - Umino, Susumu
AU - Kanayama, Kyoko
AU - Kitamura, Keitaro
AU - Tamura, Akihiro
AU - Ishizuka, Osamu
AU - Senda, Ryoko
AU - Arai, Shoji
PY - 2018/1
Y1 - 2018/1
N2 - Boninites are widely distributed along the western margin of the Pacific Plate extruded during the incipient stage of the subduction zone development in the early Paleogene period. This paper discusses the genetic relationships of boninite and antecedent protoarc basalt magmas and demonstrates their recycled ancient slab origin based on the T–P conditions and Pb–Hf–Nd–Os isotopic modeling. Primitive melt inclusions in chrome spinel from Ogasawara and Guam islands show severely depleted high-SiO2, MgO (high-silica) and less depleted low-SiO2, MgO (low-silica and ultralow-silica) boninitic compositions. The genetic conditions of 1 346 °C at 0.58 GPa and 1 292 °C at 0.69 GPa for the low- and ultralow-silica boninite magmas lie on adiabatic melting paths of depleted mid-ocean ridge basalt mantle with a potential temperature of 1 430 °C in Ogasawara and of 1 370 °C in Guam, respectively. This is consistent with the model that the low- and ultralow-silica boninites were produced by remelting of the residue of the protoarc basalt during the forearc spreading immediately following the subduction initiation. In contrast, the genetic conditions of 1 428 °C and 0.96 GPa for the high-silica boninite magma is reconciled with the ascent of more depleted harzburgitic source which pre-existed below the Izu–Ogasawara–Mariana forearc region before the subduction started. Mixing calculations based on the Pb–Nd–Hf isotopic data for the Mariana protoarc basalt and boninites support the above remelting model for the (ultra)low-silica boninite and the discrete harzburgite source for the high-silica boninite. Yb–Os isotopic modeling of the high-Si boninite source indicates 18–30 wt% melting of the primitive upper mantle at 1.5–1.7 Ga, whereas the source mantle of the protoarc basalt, the residue of which became the source of the (ultra)low-Si boninite, experienced only 3.5–4.0 wt% melt depletion at 3.6–3.1 Ga, much earlier than the average depleted mid-ocean ridge basalt mantle with similar degrees of melt depletion at 2.6–2.2 Ga.
AB - Boninites are widely distributed along the western margin of the Pacific Plate extruded during the incipient stage of the subduction zone development in the early Paleogene period. This paper discusses the genetic relationships of boninite and antecedent protoarc basalt magmas and demonstrates their recycled ancient slab origin based on the T–P conditions and Pb–Hf–Nd–Os isotopic modeling. Primitive melt inclusions in chrome spinel from Ogasawara and Guam islands show severely depleted high-SiO2, MgO (high-silica) and less depleted low-SiO2, MgO (low-silica and ultralow-silica) boninitic compositions. The genetic conditions of 1 346 °C at 0.58 GPa and 1 292 °C at 0.69 GPa for the low- and ultralow-silica boninite magmas lie on adiabatic melting paths of depleted mid-ocean ridge basalt mantle with a potential temperature of 1 430 °C in Ogasawara and of 1 370 °C in Guam, respectively. This is consistent with the model that the low- and ultralow-silica boninites were produced by remelting of the residue of the protoarc basalt during the forearc spreading immediately following the subduction initiation. In contrast, the genetic conditions of 1 428 °C and 0.96 GPa for the high-silica boninite magma is reconciled with the ascent of more depleted harzburgitic source which pre-existed below the Izu–Ogasawara–Mariana forearc region before the subduction started. Mixing calculations based on the Pb–Nd–Hf isotopic data for the Mariana protoarc basalt and boninites support the above remelting model for the (ultra)low-silica boninite and the discrete harzburgite source for the high-silica boninite. Yb–Os isotopic modeling of the high-Si boninite source indicates 18–30 wt% melting of the primitive upper mantle at 1.5–1.7 Ga, whereas the source mantle of the protoarc basalt, the residue of which became the source of the (ultra)low-Si boninite, experienced only 3.5–4.0 wt% melt depletion at 3.6–3.1 Ga, much earlier than the average depleted mid-ocean ridge basalt mantle with similar degrees of melt depletion at 2.6–2.2 Ga.
UR - http://www.scopus.com/inward/record.url?scp=85039859309&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85039859309&partnerID=8YFLogxK
U2 - 10.1111/iar.12221
DO - 10.1111/iar.12221
M3 - Article
AN - SCOPUS:85039859309
VL - 27
JO - Island Arc
JF - Island Arc
SN - 1038-4871
IS - 1
M1 - e12221
ER -