11:30 AM - 11:45 AM
[SGL28-10] Revised Cenozoic chronostratigraphy and tectonics in the Yatsuo Area, Toyama Prefecture, central Japan
Keywords:Cenozoic, chronostratigraphy, U-Pb dating, Fission-Track dating, diatom, tectonics
Facies and sequence stratigraphic analysis of the lowermost Nirehara Formation clarifies that the Nirehara Formation comprises many depositional cycles formed by sea level or lake level fluctuation in a coastal or lacustrine fan delta environment. The results also suggest that the Nirehara Formation was formed in an early rift basin, which is overlain by the syn-rift Yatsuo Group with an unconformity. Detrital zircon U-Pb and FT dating of sandstone in the Nirehara Formation suggests that possible source of sandstone was the Nohi Rhyolite.
Regional correlation of onshore and offshore Cenozoic chronostratigraphy in the Hokuriku district shows multistage rifting during Oligocene-Middle Miocene opening of the Sea of Japan. The regional correlation also suggests that post-rifting compressive tectonics was also incremental associated with fluctuation of strength and direction of compressive stress fields.