Abstract
We conducted U-Pb dating on zircon crystals separated from two drill core samples to ascertain whether a tonalite body discovered by drilling in Matsukawaura east of the Futaba Fault near the city of Soma, belongs to a 300-Ma Paleozoic granite, or to Cretaceous granitoids with age common to the Abukuma Highlands or the Kitakami Mountains. The zircons yield U-Pb ages of 115-114 Ma, which are slightly older than the age of Abukuma granitoids exposed to the area between the Hatagawa and Futaba faults (108-106 Ma). The Matsukawaura tonalite, having a typical adakitic signature, exhibits similarity to Cretaceous Takase Granite in Wariyama Sheared Granodiorite occurring along the east side of the Futaba Fault.
