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Mathilde Cannat - One of the best experts on this subject based on the ideXlab platform.
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can high temperature high heat flux hydrothermal vent fields be explained by thermal convection in the Lower Crust along fast spreading mid ocean ridges
Geochemistry Geophysics Geosystems, 2017Co-Authors: Fabrice J Fontaine, Michel Rabinowicz, Mathilde CannatAbstract:We present numerical models to explore possible couplings along the axis of fast-spreading ridges, between hydrothermal convection in the upper Crust and magmatic flow in the Lower Crust. In an end-member category of models corresponding to effective viscosities μM Lower than 1013 Pa.s in a melt-rich Lower Crustal along-axis corridor and permeability k not exceeding ∼10−16 m2 in the upper Crust, the hot, melt-rich, gabbroic Lower Crust convects as a viscous fluid, with convection rolls parallel to the ridge axis. In these models, we show that the magmatic-hydrothermal interface settles at realistic depths for fast ridges, i.e., 1–2 km below seafloor. Convection cells in both horizons are strongly coupled and kilometer-wide hydrothermal upflows/plumes, spaced by 8–10 km, arise on top of the magmatic upflows. Such magmatic-hydrothermal convective couplings may explain the distribution of vent fields along the East (EPR) and South-East Pacific Rise (SEPR). The Lower Crustal plumes deliver melt locally at the top of the magmatic horizon possibly explaining the observed distribution of melt-rich regions/pockets in the axial melt lenses of EPR and SEPR. Crystallization of this melt provides the necessary latent heat to sustain permanent ∼100 MW vents fields. Our models also contribute to current discussions on how the Lower Crust forms at fast ridges: they provide a possible mechanism for focused transport of melt-rich crystal mushes from moho level to the axial melt lens where they further crystallize, feed eruptions, and are transported both along and off-axis to produce the Lower Crust.
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Can high-temperature, high-heat flux hydrothermal vent fields be explained by thermal convection in the Lower Crust along fast-spreading Mid-Ocean Ridges?
Geochemistry Geophysics Geosystems, 2017Co-Authors: Fabrice Fontaine, Michel Rabinowicz, Mathilde CannatAbstract:We present numerical models to explore possible couplings along the axis of fast-spreading ridges, between hydrothermal convection in the upper Crust and magmatic flow in the Lower Crust. In an end-member category of models corresponding to effective viscosities l M Lower than 10 13 Pa.s in a melt-rich Lower Crustal along-axis corridor and permeability k not exceeding 10 216 m 2 in the upper Crust, the hot, melt-rich, gabbroic Lower Crust convects as a viscous fluid, with convection rolls parallel to the ridge axis. In these models, we show that the magmatic-hydrothermal interface settles at realistic depths for fast ridges, i.e., 1–2 km below seafloor. Convection cells in both horizons are strongly coupled and kilometer-wide hydrothermal upflows/plumes, spaced by 8–10 km, arise on top of the magmatic upflows. Such magmatic-hydrothermal convective couplings may explain the distribution of vent fields along the East (EPR) and SouthEast Pacific Rise (SEPR). The Lower Crustal plumes deliver melt locally at the top of the mag-matic horizon possibly explaining the observed distribution of melt-rich regions/pockets in the axial melt lenses of EPR and SEPR. Crystallization of this melt provides the necessary latent heat to sustain permanent 100 MW vents fields. Our models also contribute to current discussions on how the Lower Crust forms at fast ridges: they provide a possible mechanism for focused transport of melt-rich crystal mushes from moho level to the axial melt lens where they further crystallize, feed eruptions, and are transported both along and off-axis to produce the Lower Crust.
Kazue Suzuki - One of the best experts on this subject based on the ideXlab platform.
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ancient oceanic Crust in island arc Lower Crust evidence from oxygen isotopes in zircons from the tanzawa tonalitic pluton
Lithos, 2015Co-Authors: Kazue Suzuki, Kouki Kitajima, Yusuke Sawaki, Kentaro Hattori, Takafumi Hirata, Shigenori MaruyamaAbstract: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 (4–9 Ma), 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.
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zircon u pb dating from the mafic enclaves in the tanzawa tonalitic pluton japan implications for arc history and formation age of the Lower Crust
Lithos, 2014Co-Authors: Kazue Suzuki, Yusuke Sawaki, Takafumi Hirata, Shinji Yamamoto, Kazumasa Aoki, Soichi Omori, Yibing Li, Yutaro Takaya, Koichiro Fujinaga, Yasuhiro KatoAbstract:Abstract The petro-chemical characteristics of the arc Lower-Crust, important for understanding continental growth, have been rarely obtained because of their scarcity at the surface of the Earth. To constrain the formation age of the arc Lower-Crust, U–Pb zircon dating was applied to mafic enclaves in tonalites of the Tanzawa Tonalitic Pluton (TTP), which is regarded as the exposed middle Crust of the former Izu–Bonin–Mariana arc, using a laser ablation-inductively coupled plasma–mass spectrometer (LA-ICP-MS). The texture and shape of mafic enclaves indicate an injection of mafic magma into tonalitic magma at the mid-Crustal level. While 44 zircon grains from a host tonalite show a narrow-age distribution with a mean age of 4.6 ± 0.2 Ma, 301 zircon grains from 9 mafic enclaves show wide-age distributions from ca. 5 to 43 Ma. This study is the first to reveal a U–Pb age older than previously reported for the rock materials that compose the TTP, now identified to be 18 Ma compared with an age range from 4 Ma to 9 Ma. Because there are no other components of the TTP yet identified to be older than 17 Ma, the zircons separated from the TTP in this study which dated to be 18–43 Ma are interpreted to be xenocrysts derived from the arc Lower-Crust beneath the TTP. The oldest zircon age obtained from the mafic enclaves indicates that the formation of the arc Lower-Crust beneath TTP took place before 42.9 ± 8.6 Ma, consistent with the history of the Izu–Bonin–Mariana arc. This is the first time that the formation age of the Lower Crust has been estimated using zircons from mafic enclaves. This study shows that the zircon U–Pb dating from mafic enclaves in granites can yield significant information about the age of the continental Lower Crust.
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zircon u pb dating from the mafic enclaves in the tanzawa tonalitic pluton japan implications for arc history and formation age of the Lower Crust
Lithos, 2014Co-Authors: Kazue Suzuki, Yusuke Sawaki, Takafumi Hirata, Shinji Yamamoto, Kazumasa Aoki, Soichi Omori, Yutaro Takaya, Koichiro Fujinaga, Yoshiaki Kon, Yasuhiro KatoAbstract:Abstract The petro-chemical characteristics of the arc Lower-Crust, important for understanding continental growth, have been rarely obtained because of their scarcity at the surface of the Earth. To constrain the formation age of the arc Lower-Crust, U–Pb zircon dating was applied to mafic enclaves in tonalites of the Tanzawa Tonalitic Pluton (TTP), which is regarded as the exposed middle Crust of the former Izu–Bonin–Mariana arc, using a laser ablation-inductively coupled plasma–mass spectrometer (LA-ICP-MS). The texture and shape of mafic enclaves indicate an injection of mafic magma into tonalitic magma at the mid-Crustal level. While 44 zircon grains from a host tonalite show a narrow-age distribution with a mean age of 4.6 ± 0.2 Ma, 301 zircon grains from 9 mafic enclaves show wide-age distributions from ca. 5 to 43 Ma. This study is the first to reveal a U–Pb age older than previously reported for the rock materials that compose the TTP, now identified to be 18 Ma compared with an age range from 4 Ma to 9 Ma. Because there are no other components of the TTP yet identified to be older than 17 Ma, the zircons separated from the TTP in this study which dated to be 18–43 Ma are interpreted to be xenocrysts derived from the arc Lower-Crust beneath the TTP. The oldest zircon age obtained from the mafic enclaves indicates that the formation of the arc Lower-Crust beneath TTP took place before 42.9 ± 8.6 Ma, consistent with the history of the Izu–Bonin–Mariana arc. This is the first time that the formation age of the Lower Crust has been estimated using zircons from mafic enclaves. This study shows that the zircon U–Pb dating from mafic enclaves in granites can yield significant information about the age of the continental Lower Crust.
Michel Rabinowicz - One of the best experts on this subject based on the ideXlab platform.
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can high temperature high heat flux hydrothermal vent fields be explained by thermal convection in the Lower Crust along fast spreading mid ocean ridges
Geochemistry Geophysics Geosystems, 2017Co-Authors: Fabrice J Fontaine, Michel Rabinowicz, Mathilde CannatAbstract:We present numerical models to explore possible couplings along the axis of fast-spreading ridges, between hydrothermal convection in the upper Crust and magmatic flow in the Lower Crust. In an end-member category of models corresponding to effective viscosities μM Lower than 1013 Pa.s in a melt-rich Lower Crustal along-axis corridor and permeability k not exceeding ∼10−16 m2 in the upper Crust, the hot, melt-rich, gabbroic Lower Crust convects as a viscous fluid, with convection rolls parallel to the ridge axis. In these models, we show that the magmatic-hydrothermal interface settles at realistic depths for fast ridges, i.e., 1–2 km below seafloor. Convection cells in both horizons are strongly coupled and kilometer-wide hydrothermal upflows/plumes, spaced by 8–10 km, arise on top of the magmatic upflows. Such magmatic-hydrothermal convective couplings may explain the distribution of vent fields along the East (EPR) and South-East Pacific Rise (SEPR). The Lower Crustal plumes deliver melt locally at the top of the magmatic horizon possibly explaining the observed distribution of melt-rich regions/pockets in the axial melt lenses of EPR and SEPR. Crystallization of this melt provides the necessary latent heat to sustain permanent ∼100 MW vents fields. Our models also contribute to current discussions on how the Lower Crust forms at fast ridges: they provide a possible mechanism for focused transport of melt-rich crystal mushes from moho level to the axial melt lens where they further crystallize, feed eruptions, and are transported both along and off-axis to produce the Lower Crust.
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Can high-temperature, high-heat flux hydrothermal vent fields be explained by thermal convection in the Lower Crust along fast-spreading Mid-Ocean Ridges?
Geochemistry Geophysics Geosystems, 2017Co-Authors: Fabrice Fontaine, Michel Rabinowicz, Mathilde CannatAbstract:We present numerical models to explore possible couplings along the axis of fast-spreading ridges, between hydrothermal convection in the upper Crust and magmatic flow in the Lower Crust. In an end-member category of models corresponding to effective viscosities l M Lower than 10 13 Pa.s in a melt-rich Lower Crustal along-axis corridor and permeability k not exceeding 10 216 m 2 in the upper Crust, the hot, melt-rich, gabbroic Lower Crust convects as a viscous fluid, with convection rolls parallel to the ridge axis. In these models, we show that the magmatic-hydrothermal interface settles at realistic depths for fast ridges, i.e., 1–2 km below seafloor. Convection cells in both horizons are strongly coupled and kilometer-wide hydrothermal upflows/plumes, spaced by 8–10 km, arise on top of the magmatic upflows. Such magmatic-hydrothermal convective couplings may explain the distribution of vent fields along the East (EPR) and SouthEast Pacific Rise (SEPR). The Lower Crustal plumes deliver melt locally at the top of the mag-matic horizon possibly explaining the observed distribution of melt-rich regions/pockets in the axial melt lenses of EPR and SEPR. Crystallization of this melt provides the necessary latent heat to sustain permanent 100 MW vents fields. Our models also contribute to current discussions on how the Lower Crust forms at fast ridges: they provide a possible mechanism for focused transport of melt-rich crystal mushes from moho level to the axial melt lens where they further crystallize, feed eruptions, and are transported both along and off-axis to produce the Lower Crust.
Takafumi Hirata - One of the best experts on this subject based on the ideXlab platform.
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ancient oceanic Crust in island arc Lower Crust evidence from oxygen isotopes in zircons from the tanzawa tonalitic pluton
Lithos, 2015Co-Authors: Kazue Suzuki, Kouki Kitajima, Yusuke Sawaki, Kentaro Hattori, Takafumi Hirata, Shigenori MaruyamaAbstract: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 (4–9 Ma), 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.
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zircon u pb dating from the mafic enclaves in the tanzawa tonalitic pluton japan implications for arc history and formation age of the Lower Crust
Lithos, 2014Co-Authors: Kazue Suzuki, Yusuke Sawaki, Takafumi Hirata, Shinji Yamamoto, Kazumasa Aoki, Soichi Omori, Yibing Li, Yutaro Takaya, Koichiro Fujinaga, Yasuhiro KatoAbstract:Abstract The petro-chemical characteristics of the arc Lower-Crust, important for understanding continental growth, have been rarely obtained because of their scarcity at the surface of the Earth. To constrain the formation age of the arc Lower-Crust, U–Pb zircon dating was applied to mafic enclaves in tonalites of the Tanzawa Tonalitic Pluton (TTP), which is regarded as the exposed middle Crust of the former Izu–Bonin–Mariana arc, using a laser ablation-inductively coupled plasma–mass spectrometer (LA-ICP-MS). The texture and shape of mafic enclaves indicate an injection of mafic magma into tonalitic magma at the mid-Crustal level. While 44 zircon grains from a host tonalite show a narrow-age distribution with a mean age of 4.6 ± 0.2 Ma, 301 zircon grains from 9 mafic enclaves show wide-age distributions from ca. 5 to 43 Ma. This study is the first to reveal a U–Pb age older than previously reported for the rock materials that compose the TTP, now identified to be 18 Ma compared with an age range from 4 Ma to 9 Ma. Because there are no other components of the TTP yet identified to be older than 17 Ma, the zircons separated from the TTP in this study which dated to be 18–43 Ma are interpreted to be xenocrysts derived from the arc Lower-Crust beneath the TTP. The oldest zircon age obtained from the mafic enclaves indicates that the formation of the arc Lower-Crust beneath TTP took place before 42.9 ± 8.6 Ma, consistent with the history of the Izu–Bonin–Mariana arc. This is the first time that the formation age of the Lower Crust has been estimated using zircons from mafic enclaves. This study shows that the zircon U–Pb dating from mafic enclaves in granites can yield significant information about the age of the continental Lower Crust.
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zircon u pb dating from the mafic enclaves in the tanzawa tonalitic pluton japan implications for arc history and formation age of the Lower Crust
Lithos, 2014Co-Authors: Kazue Suzuki, Yusuke Sawaki, Takafumi Hirata, Shinji Yamamoto, Kazumasa Aoki, Soichi Omori, Yutaro Takaya, Koichiro Fujinaga, Yoshiaki Kon, Yasuhiro KatoAbstract:Abstract The petro-chemical characteristics of the arc Lower-Crust, important for understanding continental growth, have been rarely obtained because of their scarcity at the surface of the Earth. To constrain the formation age of the arc Lower-Crust, U–Pb zircon dating was applied to mafic enclaves in tonalites of the Tanzawa Tonalitic Pluton (TTP), which is regarded as the exposed middle Crust of the former Izu–Bonin–Mariana arc, using a laser ablation-inductively coupled plasma–mass spectrometer (LA-ICP-MS). The texture and shape of mafic enclaves indicate an injection of mafic magma into tonalitic magma at the mid-Crustal level. While 44 zircon grains from a host tonalite show a narrow-age distribution with a mean age of 4.6 ± 0.2 Ma, 301 zircon grains from 9 mafic enclaves show wide-age distributions from ca. 5 to 43 Ma. This study is the first to reveal a U–Pb age older than previously reported for the rock materials that compose the TTP, now identified to be 18 Ma compared with an age range from 4 Ma to 9 Ma. Because there are no other components of the TTP yet identified to be older than 17 Ma, the zircons separated from the TTP in this study which dated to be 18–43 Ma are interpreted to be xenocrysts derived from the arc Lower-Crust beneath the TTP. The oldest zircon age obtained from the mafic enclaves indicates that the formation of the arc Lower-Crust beneath TTP took place before 42.9 ± 8.6 Ma, consistent with the history of the Izu–Bonin–Mariana arc. This is the first time that the formation age of the Lower Crust has been estimated using zircons from mafic enclaves. This study shows that the zircon U–Pb dating from mafic enclaves in granites can yield significant information about the age of the continental Lower Crust.
Yusuke Sawaki - One of the best experts on this subject based on the ideXlab platform.
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ancient oceanic Crust in island arc Lower Crust evidence from oxygen isotopes in zircons from the tanzawa tonalitic pluton
Lithos, 2015Co-Authors: Kazue Suzuki, Kouki Kitajima, Yusuke Sawaki, Kentaro Hattori, Takafumi Hirata, Shigenori MaruyamaAbstract: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 (4–9 Ma), 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.
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zircon u pb dating from the mafic enclaves in the tanzawa tonalitic pluton japan implications for arc history and formation age of the Lower Crust
Lithos, 2014Co-Authors: Kazue Suzuki, Yusuke Sawaki, Takafumi Hirata, Shinji Yamamoto, Kazumasa Aoki, Soichi Omori, Yibing Li, Yutaro Takaya, Koichiro Fujinaga, Yasuhiro KatoAbstract:Abstract The petro-chemical characteristics of the arc Lower-Crust, important for understanding continental growth, have been rarely obtained because of their scarcity at the surface of the Earth. To constrain the formation age of the arc Lower-Crust, U–Pb zircon dating was applied to mafic enclaves in tonalites of the Tanzawa Tonalitic Pluton (TTP), which is regarded as the exposed middle Crust of the former Izu–Bonin–Mariana arc, using a laser ablation-inductively coupled plasma–mass spectrometer (LA-ICP-MS). The texture and shape of mafic enclaves indicate an injection of mafic magma into tonalitic magma at the mid-Crustal level. While 44 zircon grains from a host tonalite show a narrow-age distribution with a mean age of 4.6 ± 0.2 Ma, 301 zircon grains from 9 mafic enclaves show wide-age distributions from ca. 5 to 43 Ma. This study is the first to reveal a U–Pb age older than previously reported for the rock materials that compose the TTP, now identified to be 18 Ma compared with an age range from 4 Ma to 9 Ma. Because there are no other components of the TTP yet identified to be older than 17 Ma, the zircons separated from the TTP in this study which dated to be 18–43 Ma are interpreted to be xenocrysts derived from the arc Lower-Crust beneath the TTP. The oldest zircon age obtained from the mafic enclaves indicates that the formation of the arc Lower-Crust beneath TTP took place before 42.9 ± 8.6 Ma, consistent with the history of the Izu–Bonin–Mariana arc. This is the first time that the formation age of the Lower Crust has been estimated using zircons from mafic enclaves. This study shows that the zircon U–Pb dating from mafic enclaves in granites can yield significant information about the age of the continental Lower Crust.
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zircon u pb dating from the mafic enclaves in the tanzawa tonalitic pluton japan implications for arc history and formation age of the Lower Crust
Lithos, 2014Co-Authors: Kazue Suzuki, Yusuke Sawaki, Takafumi Hirata, Shinji Yamamoto, Kazumasa Aoki, Soichi Omori, Yutaro Takaya, Koichiro Fujinaga, Yoshiaki Kon, Yasuhiro KatoAbstract:Abstract The petro-chemical characteristics of the arc Lower-Crust, important for understanding continental growth, have been rarely obtained because of their scarcity at the surface of the Earth. To constrain the formation age of the arc Lower-Crust, U–Pb zircon dating was applied to mafic enclaves in tonalites of the Tanzawa Tonalitic Pluton (TTP), which is regarded as the exposed middle Crust of the former Izu–Bonin–Mariana arc, using a laser ablation-inductively coupled plasma–mass spectrometer (LA-ICP-MS). The texture and shape of mafic enclaves indicate an injection of mafic magma into tonalitic magma at the mid-Crustal level. While 44 zircon grains from a host tonalite show a narrow-age distribution with a mean age of 4.6 ± 0.2 Ma, 301 zircon grains from 9 mafic enclaves show wide-age distributions from ca. 5 to 43 Ma. This study is the first to reveal a U–Pb age older than previously reported for the rock materials that compose the TTP, now identified to be 18 Ma compared with an age range from 4 Ma to 9 Ma. Because there are no other components of the TTP yet identified to be older than 17 Ma, the zircons separated from the TTP in this study which dated to be 18–43 Ma are interpreted to be xenocrysts derived from the arc Lower-Crust beneath the TTP. The oldest zircon age obtained from the mafic enclaves indicates that the formation of the arc Lower-Crust beneath TTP took place before 42.9 ± 8.6 Ma, consistent with the history of the Izu–Bonin–Mariana arc. This is the first time that the formation age of the Lower Crust has been estimated using zircons from mafic enclaves. This study shows that the zircon U–Pb dating from mafic enclaves in granites can yield significant information about the age of the continental Lower Crust.
