Table 3 Whole rock K-Ar dating of the ejecta of Takamatsu crater sample # locali Rock name Isotope ag 40Ar* %40Ar* %K Ma scc/gm*10-5 TK21-3-G 1 glass 12.8±3.8 0.138 9.5 2.92 0.153 9.3 2.91 94070205 2 biotite daci14.2±0.7 0.163 74.1 2.97 0.166 73.7 2.97 TKC-2-07 1 aphyric rhyo14.0±0.7 0.167 74.4 3.02 0.163 78.6 3.03 TKC-2-20A 1 aphyric rhyo13.8±0.7 0.162 67.0 2.99 0.159 69.3 2.98 TKC-2-20B 1 glass <19.5 0.218 4.4 2.86 0.219 4.5 2.87 TKC-2-21A 1 glass <21.7 0.241 4.6 2.87 0.246 4.8 2.87 TKC-2-21B 1 aphyric rhyo14.2±0.7 0.170 71.6 3.06 0.168 69.6 3.05