[S-GL42_29PO1] Geochronology and Isotope Geology

[SGL42-P02] Unspiked K-Ar dating for lavas from Zao volcano

*Seiko YAMASAKI¹, Teruki OIKAWA¹, Masao BAN² (1.Geological Survey of Japan, AIST, 2.Faculty of Science, Yamagata Univ.)

Keywords:Zao volcano, K-Ar dating

Zao volcano is located in the central part on the volcanic front of the NE Japan arc. Previous study revealed that the onset of the volcanic activity is ca. 0.8 Ma, the main edifice-building stage is ca. 0.3-0.1 Ma, and the newest stage is from 0.03 Ma to the present. On this volcano, about 50 K-Ar age data are reported, but not all units are covered and some data contradict the stratigraphy probably because of low-K and/or excess Ar contamination. We report new unspiked K-Ar age data for the lavas collected also from unexplored units, in order to construct the detailed history of the volcano.