A long-lived tectono-metamorphic event in the late Paleoproterozoic: Evidence from SIMS U–Th–Pb dating of monazite from metapelite in central-south Trans-North China Orogen

Abstract

As a key accessory mineral in metapelite, monazite forms in the metamorphic event and therefore, places important direct constraint on the timing of the tectono-metamorphic event. In this study, we investigate four representative metapelites from different metamorphic terranes in the central-south Trans-North China Orogen (TNCO), applying secondary ion mass spectrometry (SIMS) U–Th–Pb dating on monazite. The dating results reveal that monazite collected from the Huashan, Luoning, Zanhuang and Wutai metamorphic complexes record the metamorphic ages of ~1.83 Ga, ~1.95 Ga, ~1.85 Ga and ~1.91 to 1.83 Ga, respectively. Combined with the literature data of metamorphic geochronology on the discrete terranes within the TNCO, it is suggested that the amalgamation between the Western and Eastern Blocks of the North China Craton along the nearly NS-trending TNCO stared as earlier as ~1.97 Ga and continued to as late as ~1.80 Ga, which was in fact a long-lived tectono-metamorphic event.