Whole-rock K-Ar age for a basaltic andesite from the Uegusukudake Formation in Kume-jima, Central Ryukyu Arc.
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- KITAGAWA Hiroshi
- Department of Physics and Earth Sciences, University of the Ryukyus
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- SHINJO Ryuichi
- Department of Physics and Earth Sciences, University of the Ryukyus
Bibliographic Information
- Other Title
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- 中琉球弧久米島宇江城岳層の玄武岩質安山岩の全岩Ｋ‐Ａｒ年代
- 中琉球弧久米島宇江城岳層の玄武岩質安山岩の全岩K-Ar年代
- チュウ リュウキュウ コ クメジマ ウエグスクダケソウ ノ ゲンブガンシツ アンザンガン ノ ゼン ガン K Ar ネンダイ
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Abstract
Whole-rock K-Ar dating for a basaltic andesite lava from the Uegusukudake Formation in Kume-jima, Central Ryukyu Arc, yields age of 2.13±0.19 Ma. The sample dated is from the middle horizon of the Formation. This age is compatible with recently published K-Ar ages of 2.76±0.48 and 2.24±0.10 Ma for a picrite basalt from the lowest part and an andesite from the upper part of the Formation, respectively. The age, however, is inconsistent with the previously reported K-Ar ages of 5.5 and 4.6 Ma. The result is also concordant with ages estimated from Sr isotopic ratios for molluscan fossils (∼3.2-3.1 Ma) for the Aka Formation underlying the Uegusukudake Formation. This result suggests that tholeiitic basalts and basaltic andesites erupted after the eruption of picrite basalts with a short time interval at the late Pliocene.
Journal
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- Japanese Magazine of Mineralogical and Petrological Sciences
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Japanese Magazine of Mineralogical and Petrological Sciences 30 (5), 237-240, 2001
Japan Association of Mineralogical Sciences
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Keywords
Details 詳細情報について
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- CRID
- 1390001206525046016
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- NII Article ID
- 10006651321
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- NII Book ID
- AA1146088X
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- COI
- 1:CAS:528:DC%2BD3MXns1Cltr4%3D
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- ISSN
- 13497979
- 1345630X
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- NDL BIB ID
- 5924799
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- Abstract License Flag
- Disallowed