ON THE AGE OF THE XINQIAO MASSIF

The Xinqiao massif in Datian, Fujian, occurs as a batholith in the middle part of the Zhenghe-Dapu deep fracture belt. This massif consists mainly of typical remoulded granite resulting from metamorphism, metasomatism and partial melting. But divergent views exist as to its age. Some people consider it to be of Hercynian age, while others consider it to be early Yanshanian in age. According to a comprehensive analysis of the isotopic age determination, zircon mineralogy and region geoloical setting of the massif, it may be considered that the 410 Ma zircon U-Pb age is the age of crystallization of zircon when the protolith was reconstituted into granite by means of metamorphism and metasomatism or partial melting. Therefore the age of the massif should be Caledonian, but the possibility of the local existence of a Hercynian massif and its influence is not ruled out.