Exploration Geology of Clustered Calderas in the Hakkoda Volcanic Field, Japan

Abstract

The Hakkoda volcanic field occurs in northern Honshu and contains five calderas of which two, the Hakkoda and Towada, were recognised prior to this study. Geologic sensing, geological mapping, age dating and petrochemical studies were out on Pliocene and early Pleistocenerocks. Three new calderas were found within a 40 km by 40 km area and that have formed during the last 3.5Ma. The five calderas are classified into the Valles-type and Crater Lake-type; they differ according to their eruption volume, collapse structure and evolution. The five calderas may have formed under the Chilean-type and Northeast Japan-type subduction regimes. The major hydrothermal systems in the volcanic field are controlled by these calderas.