Open AccessStructural variations of arc crusts and rifted margins in the southern Izu‐Ogasawara arc–back arc system
Author(s) -
Takahashi Narumi,
Kodaira Shuichi,
Tatsumi Yoshiyuki,
Yamashita Mikiya,
Sato Takeshi,
Kaiho Yuka,
Miura Seiichi,
No Tetsuo,
Takizawa Kaoru,
Kaneda Yoshiyuki
Publication year - 2009
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2008gc002146
Subject(s) - geology , crust , arc (geometry) , island arc , volcano , magmatism , volcanic arc , mantle (geology) , seismology , andesite , subduction , geochemistry , volcanic rock , tectonics , geometry , mathematics
We carried out a reflection/refraction seismic survey across the southern Izu‐Ogasawara arc–back arc system, covering three arcs with different crustal ages. The oldest Eocene arc has middle and lower crust with high velocities of 6.4–6.6 and 6.8–7.4 km/s, respectively, suggesting denser crustal materials. The current volcanic arc has middle and lower crust with lower velocities of 5.7–6.5 and 6.7–7.1 km/s, suggesting advanced crustal differentiation. The crust‐mantle transition layer, with a velocity of 7.5–8.0 km/s, is distributed beneath the current volcanic arc and the rear arc, suggesting a pool of dense materials emanating from the crust through the crustal growth. These structural differences between the Eocene arc and current arc indicate a difference of crustal growth based on basaltic and andesitic magmas according to known petrologic studies. Commonly, rifted crusts have lower crusts with high velocities of over 7.0 km/s, and the arc–back arc transition zone also has a thinner more reflective crust that may have been affected by postrifting magmatism.