Isotopic ages of the Usukigawa quartzdiorite along the Usuki-Yatsushiro Tectonic Line in eastern Kyushu and their geological significance.

秀雄, 高木; 賢, 柴田; 和博, 鈴木; 剛, 田中; 寛, 上田

doi:10.5575/geosoc.103.368

Cited by 18 publications

(12 citation statements)

References 3 publications

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“…The initial Sr isotopic ratio of 0.7055 for the garnet-biotite granodiorite clasts in the Kozaki Formation is higher than the ratios around 0.7040 reported for the Permian granitic rocks from the Akaishi Range (Hyogoshi) and the eastern Kyushu areas (Usukigawa) and the corresponding Permian granitic clasts ("Usuginu conglomerate") in the Kitakami area (Shibata and Takagi, 1989;Shibata et al, 1993;Takagi et al, 1997) (Fig. 6).…”

Section: A Slightly Enriched Feature Of Initial Sr Isotopic Ratio Formentioning

confidence: 64%

“…The determined Rb/Sr ratios are 0.32-1.5 for the garnet-biotite granodiorite clasts in the Kozaki Formation, 0.88-3.6 (Nohda, 1973) and 0.48-2.2 (Yanagi, 1975) for the Yatsushiro granite, and 0.32 for the average of upper continental crust (Taylor and McLennan, 1985). These considerations lead to the suggestion that the protolith or protolithic melt of the garnet-biotite granodiorite recorded in the Kozaki Formation was evolved from the parent of the Yatsushiro Nohda, 1973); USKGW (Usukigawa quartzdiorite in eastern Kyushu; Takagi et al, 1997);Hyogoshi (Hyogoshi granite, Akaishi Range;Shibata et al, 1993); USGN (Granitic clasts from the Usuginu conglomerate in the Kitakami mountains; Shibata and Takagi, 1989 Sr = 0.7172, Rb = 84.3 ppm, Sr = 346.7 ppm;Shibata and Adachi, 1974). Loess (Lanzhou loess. 87 Sr/ 86 Sr = 0.714041, Rb = 83.2 ppm, Sr = 300 ppm;Nakai et al, 1993).…”

Section: A Slightly Enriched Feature Of Initial Sr Isotopic Ratio Formentioning

confidence: 99%

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Rb-Sr isotopic and REE geochemistry on garnet-biotite granodiorite clasts from the Permian Kozaki Formation, Kumamoto, Southwest Japan. A slightly enriched initial Sr isotope ratio and M-type REE tetrad pattern.

et al. 2000

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Sr isotopic ratios and Rb, Sr and REE abundances are determined for granitic clasts from the middle Permian Kozaki Formation in the Kurosegawa Belt, Kumamoto, Southwest Japan, in order to elucidate their source and formation. Garnet-biotite granodiorite clasts, uniquely found in the Kozaki Formation, show M-type REE tetrad patterns and wide variation of Rb/Sr ratios, which enable their petrogenesis and age determination. The REE patterns indicate shallow formation of the garnet-bearing granodiorite. The Rb-Sr isotopic data yield an age of 251 ± 46 Ma with an initial ratio of 0.7055 ± 0.0006. The Rb-Sr age is close to the sedimentation age of the Kozaki Formation defined by paleontological data and K-Ar ages of the corresponding granitic clasts in the Permian conglomerate ("Usuginu conglomerate") of the Kitakami area, Northeast Japan. The initial Sr isotopic ratio of 0.7055 is slightly higher than the ratios around 0.7040 reported for the Permian granitic rocks from the Akaishi Range and the eastern Kyushu and the corresponding Permian granitic clasts in the Kitakami area. The initial ratio for the garnet-biotite granodiorite clasts is also slightly higher than the ratios (0.7037 and 0.7032) at 345 and 400 Ma reported for Yatsushiro granite of the Kurosegawa Belt (Nohda, 1973;Yanagi, 1975). These Sr isotopic data suggest that the garnet-biotite granodiorite clasts correspond to rocks differentiated from the Kurosegawa granitic rocks. The Sr initial ratio of 0.7055 at 251 Ma for the garnet-bearing granodiorite clasts is slightly enriched but still primitive, and the Sr initial ratio clearly indicates that the clasts were not derived from typical-continental crust. The Rb-Sr isotopic data and our preliminary Sm-Nd isotopic data for the garnet-biotite granodiorite clasts yield ε Sr (251 Ma) = +18 and ε Nd (251 Ma) = +6, suggesting an intra-oceanic arc provenance for the garnet-biotite granodiorite body from which the clasts in the Kozaki Formation had been derived.

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Section: A Slightly Enriched Feature Of Initial Sr Isotopic Ratio Formentioning

confidence: 64%

Section: A Slightly Enriched Feature Of Initial Sr Isotopic Ratio Formentioning

confidence: 99%

Rb-Sr isotopic and REE geochemistry on garnet-biotite granodiorite clasts from the Permian Kozaki Formation, Kumamoto, Southwest Japan. A slightly enriched initial Sr isotope ratio and M-type REE tetrad pattern.

et al. 2000

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“…), was examined by Takagi et al . () and provided a whole rock Sr isochron age of 275 ± 56 Ma and hornblende K–Ar ages ranging from 266 to 272 Ma, excluding mylonite in the quartz diorite (Fig. ).…”

Section: Discussionmentioning

confidence: 99%

SHRIMP U–Pb zircon dating of the Kinshozan Quartz Diorite from the Kanto Mountains, Japan: Implications for late Paleozoic granitic activity in Japanese Islands

2016

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The new result of SHRIMP U–Pb zircon dating of the Kinshozan Quartz Diorite from the Kanto Mountains, Japan, provides 281.5 ± 1.8 Ma. The age is 30 m.y. older than the available age of the Kinshozan Quartz Diorite obtained by hornblende K–Ar method. The new U–Pb zircon age represents the time of crystallization of the Kinshozan Quartz Diorite. The hornblende K–Ar age indicates the time that the Kinshozan Quartz Diorite cooled down to 500 °C which is the closure temperature of the systematics. Permian granites are found in small exposures in Japan, and frequently referred to as 250 Ma granites. The Kinshozan Quartz Diorite is considered as a type of the 250 Ma granites, and the age was influential in establishing a model of Paleozoic tectonic evolution for the Japanese Islands. The new age of the Kinshozan Quartz Diorite provides the opportunity to re‐examine the model. The Kinshozan Quartz Diorite and other Permian granites in the south of the Median Tectonic Line of Japan were constituents of the Paleo‐Ryoke Belt. The geochemical characteristics of the granitic rocks in the Paleo‐Ryoke Belt indicated that the granitic rocks were formed in a primitive island arc environment, and the new trace element data also support this interpretation. Examination of the available data and results of the present study suggests the late Paleozoic granitic activity in Japan as follows. At about 310–290 Ma, arc magmatism generated adakitic granites and other granites in the South Kitakami Belt. Quartz diorite and tonalites of primitive characteristic, such as the Kinshozan Quartz Diorite and granites in the Maizuru Belt appear to have been formed at the immature island arc, and accreted to the Japanese Islands at the end of Paleozoic or early Mesozoic era. During 260–240 Ma, granitic activity took place in the Hida and Maizuru Belts as a part of the Asian continent.

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“…versus Rb/Sr diagram for early Permian to late Jurassic plutonic rocks around Southwest Japan and Korea. Data sources: Yamanaka granodiorite and Kunisaki tonalite ( Osanai et al 1993 ), Hida granites ( Shibata & Nozawa 1984; Tanaka & Kagami 1987b; Arakawa 1988; Shibata et al 1988 ; Arakawa 1990a; Arakawa 1990b; Tanaka 1992; Arakawa & Shinmura 1995), Kinshozan granites ( Shibata & Takagi 1989; Shibata et al 1993 ; Takagi et al 1997 ), Daebo granites ( Park 1972; Tsusue et al 1986 ; Jin 1988; Hong & Lee 1989; Jwa et al 1990 ; Kim et al 1996 ).…”

Section: Interpretation For Magmatism Of the Miyanohara Tonalitementioning

confidence: 99%

“… Assumed crystallization age (Ma) versus initial Sr ratio (SrI) for early Permian to late Jurassic plutonic rocks around SW Japan and Korea. Data sources: the Yamanaka granodiorite and the Kunisaki tonalite ( Osanai et al 1993 ), Hida granites ( Tanaka & Kagami 1987b; Arakawa 1988; Arakawa 1990a; Tanaka 1992), Kinshozan granites ( Shibata et al 1993 ; Takagi et al 1997 ), Daebo granites ( Park 1972; Jin 1988; Hong & Lee 1989; Jwa et al 1990 ). …”

Section: Interpretation For Magmatism Of the Miyanohara Tonalitementioning

confidence: 99%

Isotopic equilibration ages for the Miyanohara tonalite from the Higo metamorphic belt in central Kyushu, Southwest Japan: Implications for the tectonic setting during the Triassic

et al. 2000

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Miyanohara tonalite occurs in the middle part of the Higo metamorphic belt in the central Kyushu, Southwest Japan. This tonalite intrudes into early Permian Ryuhozan metamorphic rocks in the south and is intruded by Cretaceous Shiraishino granodiorite in the north. The Miyanohara tonalite yielded three mineral ages: (i) 110–100 Ma for Sm–Nd and Rb–Sr internal isochrons and for K–Ar hornblende; (ii) 183 Ma for Sm–Nd internal isochron; and (iii) 211 Ma for Sm–Nd internal isochron. The ages of 110–100 Ma may indicate cooling age due to the thermal effect of the Shiraishino granodiorite intrusion. The ages of 183 Ma and 211 Ma are consistent with timing of intrusion of the Miyanohara tonalite based on geologic constraints. The hornblende in the sample which gave 183 Ma shows discontinuous zoning under microscope, whereas the one which gave 211 Ma does not show zonal structure. These mineralogical features suggest that the 183 Ma sample has suffered severely from later tectonothermal effect compared with the 211 Ma sample. Therefore, the age of 211 Ma is regarded as near crystallization age for the Miyanohara tonalite. The magmatic process, geochronology and initial Sr and Nd isotope ratios for the Miyanohara tonalite are similar to those of early Jurassic granites from the Outer Plutonic Zone of the Hida belt that constitutes a marginal part of east Asia before the opening of the Japan Sea. Intrusion of the Miyanohara tonalite is considered to have taken place in the active continental margin during the late Triassic.

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Isotopic ages of the Usukigawa quartzdiorite along the Usuki-Yatsushiro Tectonic Line in eastern Kyushu and their geological significance.

Cited by 18 publications

References 3 publications

Rb-Sr isotopic and REE geochemistry on garnet-biotite granodiorite clasts from the Permian Kozaki Formation, Kumamoto, Southwest Japan. A slightly enriched initial Sr isotope ratio and M-type REE tetrad pattern.

Rb-Sr isotopic and REE geochemistry on garnet-biotite granodiorite clasts from the Permian Kozaki Formation, Kumamoto, Southwest Japan. A slightly enriched initial Sr isotope ratio and M-type REE tetrad pattern.

SHRIMP U–Pb zircon dating of the Kinshozan Quartz Diorite from the Kanto Mountains, Japan: Implications for late Paleozoic granitic activity in Japanese Islands

Isotopic equilibration ages for the Miyanohara tonalite from the Higo metamorphic belt in central Kyushu, Southwest Japan: Implications for the tectonic setting during the Triassic

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