Geochronology of alkali volcanism in Oki-Dogo Island, southwest Japan: geochemical evolution of basalts related to the opening of the Japan Sea

K. Uto, E. Takahashi, Eizou Nakamura, I. Kaneoka

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Geochronological and geochemical studies were performed on alkali volcanic rocks from Oki-Dogo Island, locating about 60 km off the coast of Southwest Japan inside the Japan Sea. There are big differences both in age and in geochemistry between the oldest alkali rocks and the younger rocks. Syn-extensional rocks should not have erupted in the active subduction zone but are probably originated from or at least contaminated by the lithosphere beneath the early Proterozoic crust. The lithosphere is considered to have suffered mantle metasomatism to form phlogopite selectively enriched in Ba and K2O by fluids, which had been released from previous subductions at the Asian continental margin. Partial melting of such lithospheric mantle during the active rifting was essential for the generation of Ba- and K2O-enriched alkali basalt magmas. The younger basaltic rocks are probably originated either from the asthenosphere or the deeper plume mantle. -from Authors

Original languageEnglish
Pages (from-to)431-449
Number of pages19
JournalGeochemical Journal
Volume28
Issue number6
Publication statusPublished - 1994

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Geochronology
geochronology
Alkalies
basalt
volcanism
alkalies
Japan
Rocks
rocks
Earth mantle
rock
lithosphere
mantle
Volcanic rocks
Geochemistry
alkali basalt
phlogopite
mantle plume
asthenosphere
metasomatism

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Geochronology of alkali volcanism in Oki-Dogo Island, southwest Japan : geochemical evolution of basalts related to the opening of the Japan Sea. / Uto, K.; Takahashi, E.; Nakamura, Eizou; Kaneoka, I.

In: Geochemical Journal, Vol. 28, No. 6, 1994, p. 431-449.

Research output: Contribution to journalArticle

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