New SHRIMP U-Pb zircon ages of granitic rocks in the Hida Belt, Japan: Implications for tectonic correlation with Jiamushi massif

Granitoids in the Hida region of Japan encompass two main rock types: younger type-1 granites and older type-2 granites. Sensitive high mass-resolution ion microprobe (SHRIMP) U-Pb zircon dating of older type-2 granites collected from the Tateyama area show similar ages of 245 +/- 2Ma and 248 +/- 5Ma for two gneissose granites, while a significantly younger intrusion age of 197 +/- 3Ma was determined for the younger type-1 granites collected from the Hayatsukigawa River which belongs to the Okumayama pluton. A felsic gneiss sample (07HI-3) collected from the right bank of the Hayatsukigawa River yielded multiple complex ages at 330 +/- 6Ma, indicating the timing of the Hida regional tectono-thermal events that formed the Hida gneisses; 243 +/- 8Ma, representing the timing of intrusion of the augen granite; and 220Ma, indicating the timing of regional dextral ductile shearing that caused a repeated recrystallization of metamorphic rocks in the study area. Considering the geochronological data, the rock types and assemblages, basement, and Sr-Nd isotopic constraints, we propose that the Hida Belt separated from the Jiamushi massif, which is located in the eastern margin of the Central Asian Orogenic Belt.