Sr isotopic study of Ibara dismembered ophiolite from the Maizuru Tectonic Belt, Southwest Japan.

Koide, Yoshiyuki; Tazaki, Koichi; Kagami, Hiroo

doi:10.2465/ganko1941.82.1

Cited by 22 publications

(12 citation statements)

References 49 publications

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“…Mudstone and basalt lava of the Maizuru Belt are distributed in the northern part of the field. The strontium isotope ratio of the metabasalt was reported by Koide et al (1987) to range from 0.704 to 0.707. The mudstone of the Tamba Belt is distributed in the southern and western parts of the field.…”

Section: Geology Of the Sanyo Regionmentioning

confidence: 98%

Strontium isotope analysis to reveal migration in relation to climate change and ritual tooth ablation of Jomon skeletal remains from western Japan

Kusaka

Nakano

Morita

et al. 2012

Journal of Anthropological Archaeology

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Section: Geology Of the Sanyo Regionmentioning

confidence: 98%

Strontium isotope analysis to reveal migration in relation to climate change and ritual tooth ablation of Jomon skeletal remains from western Japan

Kusaka

Nakano

Morita

et al. 2012

Journal of Anthropological Archaeology

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“…Shibata and Igi (1966), Hayase and Ishizaka (1967), Shibata et al (1972Shibata et al ( , 1977Shibata et al ( , 1979, Koide et al (1987), Sano (1992), Hayasaka and Ikeda (1992b), and this work.…”

mentioning

confidence: 91%

Rb-Sr ages of the Yakuno rocks from the Northern Subzone of the Maizuru Terrane, Kyoto Prefecture, Southwest Japan.

Ikeda¹,

Hayasaka

1994

J. Min. Petr. Econ. Geol.

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Rb-Sr ages of the Yakuno rocks from the Northern Subzone of the Maizuru Terrane, Kyoto Prefecture, Southwest Japan Rb-Sr isotopic age determinations were made on the basement rocks of the Northern subzone of the Maizuru Terrane in the western Maizuru City and Oe Town area. The rocks of the area consist mainly of granitic rocks with minor amounts of quartz-diorite, gabbro, diabase, and pelitic schist and amphibolite (Komori metamorphic rocks), being called the Northern Yakuno rocks. They are distinguished from the Southern Yakuno rocks which consist of ophiolitic complex (Yakuno ophiolite) lying in the Southern subzone of the terrane by their lithofacies and whole rock chemistry. The Northern Yakuno rocks are characterized by the abundance of K-feldspar rich granitic rocks, whereas the Southern Yakuno rocks do not contain such rocks. The Northern Yakuno rocks are thrust over the Shimomidani Formation of the Akiyoshi Terrane to the north in the area.The Rb-Sr mineral isochron ages were determined upon six granitic rocks and one quartzdiorite. They can be divided into two age groups, the older (around 300 Ma) and the younger (around 150 Ma). The rocks give whole rock isochron ages of 327 Ma for the older group and 149 Ma for the younger one, whose initial 87Sr/86Sr ratios are 0.70669 and 0.70779 respectively. Whole rock isochron age for the gabbros and diabases is 163 Ma, and initial 87Sr/86Sr ratio is 0.70687. Nearly coincidence between whole rock and mineral isochron ages for each age group explains the existence of two stage igneous activities at those ages in this area, despite their mylonitization and recrystallization.Both whole rock chemistry and the initial 87Sr/86Sr ratio of those rocks indicate that the Northern Yakuno rocks was evolved as an matured crust of island-arc or continent by the late Carboniferous time. In this respect, the evolutional history of the Northern subzone is quite different from that of the Southern subzone in the terrane.

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“…These results suggest that the BAB crust was brought to the magmatic arc setting soon (within several million years) after its generation. Koide et al [37] reported an Rb-Sr whole-rock-mineral isochron age of 281 ± 8 Ma for the metagabbro and metabasalt of BABB origin in the Ibara area. This age is similar to the age of radiolarians from the lower strata of the Maizuru Group and may represent the magmatic age of the mafic rocks of BABB origin without the influence of arc magmatism.…”

Section: Geotectonic Timescalementioning

confidence: 99%

Crustal Evolution of a Paleozoic Intra-oceanic Island-Arc-Back-Arc Basin System Constrained by the Geochemistry and Geochronology of the Yakuno Ophiolite, Southwest Japan

Suda

Hayasaka

Kimura

2014

Journal of Geological Research

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The Yakuno ophiolite in southwest Japan is considered to have been obducted by the collision between an intrao-ceanic islandarc-back-arc basin (intra-OIA-BAB) system and the East Asian continent during the late Paleozoic. New SIMS (SHRIMP) zircon U-Pb determinations for amphibolite and metagabbro of BAB origin within the Yakuno ophiolite yield ages of 293.4 ± 9.5 Ma and 288 ± 13 Ma, respectively. These ages are slightly older (however, overlapping within analytical errors) than the magmatic age of arc granitoids (ca. 285-282 Ma) that intruded into the mafic rocks of BAB origin. Results from geochronological and geochemical data of the Yakuno ophiolite give rise to the following tentative geotectonic model for the Paleozoic intra-OIA-BAB system: the initial stage of BAB rifting (ca. 293-288 Ma) formed the BAB crust with island-arc basalt (IAB) signatures, which was brought to the OIA setting, and generated the arc granitoids (ca. 285-282 Ma) by anatexis of the BAB crust. A later stage of BAB rifting (

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Sr isotopic study of Ibara dismembered ophiolite from the Maizuru Tectonic Belt, Southwest Japan.

Cited by 22 publications

References 49 publications

Strontium isotope analysis to reveal migration in relation to climate change and ritual tooth ablation of Jomon skeletal remains from western Japan

Strontium isotope analysis to reveal migration in relation to climate change and ritual tooth ablation of Jomon skeletal remains from western Japan

Rb-Sr ages of the Yakuno rocks from the Northern Subzone of the Maizuru Terrane, Kyoto Prefecture, Southwest Japan.

Crustal Evolution of a Paleozoic Intra-oceanic Island-Arc-Back-Arc Basin System Constrained by the Geochemistry and Geochronology of the Yakuno Ophiolite, Southwest Japan

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