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Existence of multiple units with different accretionary and metamorphic ages in the S anbagawa B elt, S akuma– T enryu area, central J apan
Author(s) -
Tsutsumi Yukiyasu,
Miyashita Atsushi,
Horie Kenji,
Shiraishi Kazuyuki
Publication year - 2012
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/iar.12001
Subject(s) - zircon , geology , sedimentary depositional environment , geochemistry , metamorphic rock , subduction , paleontology , tectonics , structural basin
U – P b ages of detrital zircons and white mica K – A r ages are obtained from two psammitic schists from the western and eastern units of the S anbagawa M etamorphic B elt located in the S akuma– T enryu area. The detrital zircons in the sample from the western unit ( T 1) show an age cluster around 95 Ma, and the youngest age in the detrital zircons is 94.0 ± 0.6 Ma. The detrital zircons in the sample from the eastern unit ( T 5) show a main age cluster in the L ate C retaceous with some older ages, and the youngest age in the detrital zircons is 72.8 ± 0.9 Ma. The youngest zircon ages restrict the older limit of the depositional ages of each sample. White mica K – A r ages of T 1 and T 5 are 69.8 ± 1.5 Ma and 56.1 ± 1.2 Ma, respectively, which indicate the age of exhumation and restrict the younger limit on the depositional age of each sample. The results show that the western and eastern units were different in their depositional and exhumation ages, suggesting the episodic subduction and exhumation of the S anbagawa B elt in the S akuma– T enryu area. These results also suggest simultaneous existence of subduction and exhumation paths of metamorphic rocks in the high‐ P / T S anbagawa M etamorphic B elt.