Genetic relationship between post-caldera and caldera-forming magmas from Aso volcano, SW Japan: Constraints from Sr isotope and trace element compositions

Miyoshi, Masaya; Shibata, Tomoyuki; Yoshikawa, Masakazu; Sano, Takashi; Shinmura, Taro; Hasenaka, Toshiaki

doi:10.2465/jmps.101021b

Cited by 18 publications

(9 citation statements)

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“…As a result, sills of dense mafic magma formed at a similar depth to that of the 4I-1 magma chamber. The postcaldera mafic magmas may have chemically interacted with the remaining crystal mush, although the Aso-4 and post-caldera basaltic-andesitic magmas have similar isotopic compositions (Miyoshi et al 2011b); consequently, their interaction is difficult to detect using isotopic data. The formation and differentiation of mafic sills at depth also created additional barriers for the ascending mafic magma.…”

Section: Pressure Conditions Of Amphibole Crystallizationmentioning

confidence: 99%

Amphibole–melt disequilibrium in silicic melt of the Aso-4 caldera-forming eruption at Aso Volcano, SW Japan

Ishibashi

Suwa

Miyoshi

et al. 2018

Earth Planets Space

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The most recent and largest caldera-forming eruption occurred at ~ 90 ka at Aso Volcano, SW Japan, and is known as the "Aso-4 eruption. " We performed chemical analyses of amphibole phenocrysts from Aso-4 pyroclasts collected from the initial and largest pyroclastic unit (4I-1) of the eruption to infer the composition-temperature-pressure conditions of the melt that crystallized amphibole phenocrysts. Each amphibole phenocryst is largely chemically homogeneous, but inter-grain chemical variation is observed. Geothermometry, geobarometry, and melt-SiO 2 relationships based on amphibole single-phase compositions reveal that most amphibole phenocrysts were in equilibrium with hydrous melt comprising ~ 63-69 wt% SiO 2 (SiO melt 2) at 910-950 °C, although several grains were crystallized from more mafic and higher-temperature melts (~ 57-60.5 wt% SiO 2 and 965-980 °C). The amphibole temperatures are comparable with those previously estimated from two-pyroxene geothermometry, but are much higher than temperatures previously estimated from Fe-Ti oxide geothermometry. The estimated SiO melt 2 contents are lower than that of the host melt in the 4I-1 pyroclasts. Chemical and thermal disequilibrium between the amphibole rims and the host melt, as well as intra-grain homogeneity and inter-grain heterogeneity of amphibole compositions, suggests that these amphiboles were incorporated into the host melt immediately prior to the caldera-forming eruption. Our results suggest that the amphibole phenocrysts, and perhaps some of the pyroxene and plagioclase phenocrysts, were derived from a chemically and thermally zoned crystal mush layer that had accumulated beneath the chamber of the host 4I-I melt. Amphibole geobarometry indicates a crystallization depth of ~ 13.9 ± 3.5 km, which is consistent with the present-day magma chamber depth beneath the volcano as inferred from geophysical observations. The results suggest that the depth of the post-caldera magma plumbing system is strongly influenced by a relic magma reservoir related to a previous caldera-forming eruption.

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Section: Pressure Conditions Of Amphibole Crystallizationmentioning

confidence: 99%

Amphibole–melt disequilibrium in silicic melt of the Aso-4 caldera-forming eruption at Aso Volcano, SW Japan

Ishibashi

Suwa

Miyoshi

et al. 2018

Earth Planets Space

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“…Data for Aira Volcano from Arakawa et al (). Data for Aso Volcano from Hunter (), Miyoshi et al (), and Kaneko et al (). IBM Arc tephra from Straub et al (, , , ), Schmidt (), and Egeberg et al ().…”

Section: Discussionmentioning

confidence: 99%

“…Pb isotopes for Honshu quaternary arc are from the Takadani Pluton (Hartung et al, ) and the Chayano‐Ebisutoge Rhyolite (Kimura & Nagahashi, ). Kyushu and Ryukyu volcanic rocks from Terakado et al (), Shinjo (), Shinjo et al (, ), Arakawa et al (), Furukawa et al (), Guo et al (), Hoang and Uto (), Honma et al (), Hosono et al (), Hunter (), Kaneko et al (), Kita et al (), Miyoshi et al (), and Shibata et al (, ). For the Izu‐Bonin Mariana field (uncorrected for time) a compilation of magmatic products from arc‐inception (ca.…”

Section: Discussionmentioning

confidence: 99%

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Isotopic Characteristics of Neogene‐Quaternary Tephra From IODP Site U1438: A Record of Explosive Volcanic Activity in the Kyushu‐Ryukyu Arc

McCarthy

Yogodzinski

Tepley

et al. 2019

Geochem Geophys Geosyst

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International Ocean Discovery program (IODP) Site U1438 is located within the Amami‐Sankaku Basin, ~50 km SW of the Kyushu‐Palau Ridge and ~500 km SE of the present‐day volcanic front of the Kyushu‐Ryukyu arc. Thirty‐eight rhyolitic tephra layers (1–15 cm thick) deposited over the last 4 Myr were recovered at this site. Representative ash layers dominated by unaltered, colorless glass shards reaching 100–300 μm in size, in association with rare pyroxene, amphibole, biotite, and zircon, were sampled for isotopic analysis. The isotopic compositions of the tephra have a narrow range in 87Sr/86Sr (0.704 to 0.706), 206Pb/204Pb (18.32 to 18.46), 207Pb/204Pb (15.57 to 15.62), and 208Pb/204Pb (38.46 to 38.75) and are more variable in εNd (−3.5 to +4.8) and εHf (+2.0 to +13.3). This record indicates the tephra were not sourced from the Izu‐Bonin‐Mariana arc or from Central Japan but derived from felsic volcanism from the Kyushu‐Ryukyu arc. The 4.8‐km‐deep Amami‐Sankaku Basin was located up to 600–900 km from the Kyushu‐Ryukyu arc over the last 4 Ma, which is significantly more distal than other drill sites from which extensive tephra layers sourced from SW Japan have been recovered. Site U1438 tephra are thus likely related to widely distributed (M > 6) rhyolitic eruptions. We propose the unique tephra record and high‐precision isotope analysis of recovered tephra from Site U1438 can be used as an important marker to identify submerged calderas within the Ryukyu arc and/or constrain the history of activity (>1 Ma) of major calderas‐forming eruptions within the Kyushu‐Ryukyu arc.

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“…1(b)), and the lava flows down mostly westward to southwestward. The volume of the lava is estimated to be 0.14 km 3 (Miyabuchi et al, 2004), and bulk rock chemistry of the lava is 70 to 72 SiO 2 wt% (Miyoshi et al, 2005(Miyoshi et al, , 2011. We examined two continuous drill cores of the Takanoobane rhyolite lava (cores AVL1 and AVL2) provided by the Aso Volcanological Laboratory of Kyoto University.…”

Section: Takanoobane Rhyolite Lavamentioning

confidence: 99%

Paleomagnetic investigation of rhyolite lava: Is rhyolite with clearly marked flow structure a high-fidelity geomagnetic field recorder?

et al. 2013

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Rhyolite is a common volcanic rock; however, few studies have focused on the remanent magnetization of rhyolite lava, and few paleomagnetic studies have successfully investigated rhyolite lavas. We suspect that problems associated with paleomagnetic studies of rhyolite may be due to the nearly ubiquitous flow structure in rhyolite lava. In this study, we examined a thick rhyolite lava flow with clearly marked flow structure to assess its ability to record a consistent paleomagnetic direction, using material penetrated by two drill cores. Progressive thermal demagnetization isolated two magnetization components. A high-temperature component from each of the two cores yields inclinations that differ from each other. The low-temperature component had those that agreed with each other, and were also consistent with the direction expected from a geocentric axial dipole field. The modification of direction of the high-temperature component may be explained by post-magnetization acquisition tilting. The development of flow structure also leads to distortion of directions of the component, which is observed at stratigraphic positions where the volume fraction of light-colored parts of the flow structure >30%. In the case of silicic lava, the low-temperature component may retain directions parallel to the ambient field direction at the time of lava emplacement.

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Genetic relationship between post-caldera and caldera-forming magmas from Aso volcano, SW Japan: Constraints from Sr isotope and trace element compositions

Cited by 18 publications

References 12 publications

Amphibole–melt disequilibrium in silicic melt of the Aso-4 caldera-forming eruption at Aso Volcano, SW Japan

Amphibole–melt disequilibrium in silicic melt of the Aso-4 caldera-forming eruption at Aso Volcano, SW Japan

Isotopic Characteristics of Neogene‐Quaternary Tephra From IODP Site U1438: A Record of Explosive Volcanic Activity in the Kyushu‐Ryukyu Arc

Paleomagnetic investigation of rhyolite lava: Is rhyolite with clearly marked flow structure a high-fidelity geomagnetic field recorder?

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