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Early Permian zircon uranium‐lead ages for plagiogranites in the Yakuno ophiolite, Asago district, Southwest Japan
Author(s) -
Herzig Charles T.,
Kimbrough David L.,
Hayasaka Yasutaka
Publication year - 1997
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/j.1440-1738.1997.tb00049.x
Subject(s) - ophiolite , zircon , geology , geochemistry , permian , island arc , petrogenesis , basement , stage (stratigraphy) , paleozoic , petrology , subduction , paleontology , tectonics , basalt , archaeology , structural basin , history
Prior work has defined a two‐stage history for Yakuno ophiolite petrogenesis consisting of older oceanic basement, and younger island‐arc rocks and subordinate elastic rocks. First‐stage Yakuno rocks have transitional‐type M orb or oceanic plateau affinities, and second‐stage Yakuno rocks are more similar to immature island‐arc settings. Zircon U‐Pb isotopic dates of plagiogranite from the Asago district of Southwest Japan yield crystallization ages of 285 ± 2 Ma for the first‐stage ophiolite component, and 282 ± 2 Ma for the second‐stage component of the ophiolite. These results indicate that the two petrologi‐cally distinct components of the Yakuno ophiolite in this area formed in a short time interval in the Early Permian. The zircon U‐Pb crystallization ages provide a maximum age for the base of the stratigraphically overlying Maizuru Group.