4D volcanic geology of Hachijo-jima islet, Izu-Bonin arc

This study combines detailed geologic mapping, tephrochronology, U-Pb zircon dating, and published drill core data to evaluate the time transgressive 3-dimensional (thus 4-dimensional) structure evolution of two volcanoes on Hachijo-jima juvenile Izu-Bonin intra oceanic arc. The regional Ata-Torihama tephra (Ata-Th; 0.24 Ma) Kikai-Tozurahara (K-Tz; 0.095 from Kyushu are intercalated within voluminous proximal volcanic products. silicic tuff cover some supra-subduction zone ophiolites, that formed in a nascent arc setting, may be ancient analogs derived adjacent but mature succession comprises submarine basement, marine volcaniclastic rocks, terrestrial with tholeiitic basalt exotic calc-alkaline layers. undissected Hachijo-Fuji stratovolcano (tholeiitic basalt) overlies volcaniclastics abutting northwestern paleo sea cliffs older dissected volcano, Mihara-yama. Newly-described folding normal faulting overlying rocks record NW-SE shortening associated collision Honshu arc, analogous NNE-SSW observed for Troodos ophiolite. proto volcano emerged above >0.24 Ma, this date can applied as molecular biological calibration organisms island.