Trace elemental and Sr-Nd-Hf isotopic compositions, and U-Pb ages for the Kitakami adakitic plutons: Insights into interactions with the early Cretaceous TRT triple junction offshore Japan

Soichi Osozawa, Tadashi Usuki, Masako Usuki, John Wakabayashi, Bor ming Jahn

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

We conducted major, trace element, Sr-Nd-Hf isotopic, and U-Pb geochronologic analyses of early Cretaceous Kitakami granitic plutons, northeast Japan. We suggest that these plutons include rocks of adakitic affinity, which indicate partial melting of an eclogitic slab. The Kitakami adakites were mostly derived from juvenile oceanic crustal sources, but include inherited zircons with Archean to Neoproterozoic Hf model ages. Rather than being directly derived from crustal rocks of these ages, zircons may have been detrital in the voluminous trench fill sandstone within the Jurassic northern Kitakami accretionary prism. The exhumation of older basement that served as the detrital zircon source may have been triggered by ridge subduction. Although the plutons show a general southward younging from northern Kitakami (120–130 Ma), southern Kitakami (115–125 Ma), and Abukuma (100–115 Ma), restoration of post-crystallization left-slip faults inverts this spatial pattern and results in a northward-younging pattern. This suggests northward migration of a trench-ridge-transform triple junction that included the Izanagi–Farallon ridge. The Sambagawa eclogite may be genetically related to the Kitakami adakite in time and space if the transform duplexing is restored.

Original languageEnglish
Article number103968
JournalJournal of Asian Earth Sciences
Volume184
DOIs
Publication statusPublished - 2019 Oct 15

Keywords

  • Calc-alkaline
  • Eclogitic slab melting
  • Exhumation
  • Ridge subduction
  • Transform fault
  • Zircon

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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