Abstract
The Kurohanayama basalt has been referred to as a representative rock of Quaternary basalts in northeast Japan. There has been a significant amount of petrological studies on these rocks, however, the effused age of the Kurohanayama basalt has not been established yet.
In this study, we determined the K-Ar ages of rocks from the Kurohanayama basalt, and obtained 5.03±0.50, 5.2±1.2 and 5.64±0.31 Ma in age. From these data, we have shown that basalts of Kurohanayama effused some time between Late Miocene and Early Pliocene (4-6 Ma). Thus, the Kurohanayama basalt is Tertiary in age, and must be genetically separated from the Quaternary Funagata volcano.
