Whole-rock K-Ar age for a basaltic andesite from the Uegusukudake Formation in Kume-jima, Central Ryukyu Arc

Hiroshi Kitagawa, Ryuichi Shinjo

Research output: Contribution to journalArticle

1 Citation (Scopus)

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.

Original languageEnglish
Pages (from-to)237-240
Number of pages4
JournalJapanese Magazine of Mineralogical and Petrological Sciences
Volume30
Issue number5
DOIs
Publication statusPublished - 2001
Externally publishedYes

Fingerprint

andesite
Rocks
Geochronology
rock
picrite
basalt
tholeiitic basalt
isotopic ratio
lava
Pliocene
volcanic eruption
fossil

Keywords

  • Basaltic andesite
  • K-Ar dating
  • Kume -jima
  • Picrite basalt
  • Pliocene
  • Ryukyu Arc
  • Uegusukudake Formation

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Economic Geology

Cite this

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title = "Whole-rock K-Ar age for a basaltic andesite from the Uegusukudake Formation in Kume-jima, Central Ryukyu Arc",
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.",
keywords = "Basaltic andesite, K-Ar dating, Kume -jima, Picrite basalt, Pliocene, Ryukyu Arc, Uegusukudake Formation",
author = "Hiroshi Kitagawa and Ryuichi Shinjo",
year = "2001",
doi = "10.2465/gkk.30.237",
language = "English",
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AU - Kitagawa, Hiroshi

AU - Shinjo, Ryuichi

PY - 2001

Y1 - 2001

N2 - 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.

AB - 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.

KW - Basaltic andesite

KW - K-Ar dating

KW - Kume -jima

KW - Picrite basalt

KW - Pliocene

KW - Ryukyu Arc

KW - Uegusukudake Formation

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