Low-temperature thermochronology of the Izu collision zone, central Japan; Implications for mountain building at an active arc-arc collision zone

Sueoka, Shigeru   ; Kobayashi, Yumi*; Fukuda, Shoma   ; Kohn, B. P.*; Yokoyama, Tatsunori   ; Sano, Naomi*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*

Multi-system thermochronometries were applied to the Izu collision zone, an active arc-arc collision zone in the central Japan, in order to reveal the mountain formation process. Nine granitic samples yielded zircon U-Pb ages of 10.2-5.8 Ma (n = 2), apatite (U-Th)/He ages of 42.8-2.6 Ma (n = 7), and apatite fission-track (AFT) ages of 44.1-3.0 Ma (n = 9). Thermal inversion analyses based on the AFT data suggest rapid cooling events at ca 5 Ma and 1 Ma in the collision zone and no such thermal/tectonic effect out of the zone. The Kanto Mountains are thought to be uplifted domally associated with the collision of the Tanzawa Block at ca 5 Ma. The Minobu Mountains and possibly the adjacent mountains could be uplifted by the collision of the Izu Block at ca 1 Ma. Mountain formation in the Izu collision zone is mainly controlled by the collisions of crustal blocks of the Izu-Bonin Arc and motional change of the Philippine Sea plate.