Zircon U-Pb dates from the Taiheizan Complex Plutons in Akita Prefecture, NE Japan

Abstract

Zircon U-Pb dating was carried out on granitic rocks from plutons in the Taiheizan Complex in Akita Prefecture, NE Japan. Two granodiorites from the Main Intrusive Rocks yielded weighted mean ²⁰⁶Pb/²³⁸U dates of 103.4±1.0 Ma and 115.6±1.1 Ma (1SE). Three porphyrygranite from the Young Intrusive Rocks yielded weighted mean ²⁰⁶Pb/²³⁸U dates of 11.4±0.1 Ma, 4.7±Ma, and 4.8±0.1 Ma (1SE). The older and younger dates can be interpreted as the ages of early and later stages of granitic intrusion at the sampling locations. The Pliocene U-Pb dates suggest that the Nibetsu Body in the Young Intrusive Rocks is one of the youngest granitic plutons currently exposed on Earth.