Zircon U-Pb Dating Constraint on the formation age of the Tananao Metamorphic Complex, Central Taiwan

The oldest rock of the Tananao Metamorphic Complex is exposed on the eastern part of the Central Range. It consists of schist, marble, and gneiss. Because of lack of fossils and radiometric dating, the formation age was difficult to confirm. U-Pb age of detrital zircon represents the age of sediment source, and the youngest age may be closed to or older than the depositional age. Therefore, we use the detrital zircon U-Pb dating to discuss the maximum depositional age of the schist formation which is divided into quartz-mica schist, metachert, green schist, and metabasite. The youngest age of the detrital zircon of 26 samples from schist formation are 86±2Ma (metachert), 91±1Ma (metachert), 93±3Ma (metabasite), 81±2Ma (quartz-mica schist), and 95±2Ma (quartz-mica schist). We suggest that the maximum depositional age of the schist formation is late Cretaceous. The marble formation, which was deposited during the Permo-Triassic period, is overlain by the schist formation. Apparently, there is an unconformity between the schist formation and marble.