Timing of the Erlangping back-arc basin in the Qinling orogen, central China and its tectonic significance

摘要

Back-arc basins hold the key in understanding the geodynamics of orogenic processes. The Qinling-Dabie orogenic belt in central China is one of the most important orogenic belts constraining the tectonic framework of eastern Asia. However, its Palaeozoic accretionary processes remain equivocal, mainly derived from the age uncertainty of the back-arc basin in the Qinling orogen. We carried out zircon U-Pb geochronology for two pyroclastic volcanic rocks intercalated within the Erlangping back-arc basin basalts. They yield U-Pb ages of 435.8 +/- 4.2 Ma and 435.7 +/- 3.8 Ma, which precisely constrain the timing of the back-arc basin opening. The opening of the Erlangping back-arc basin might have been triggered by the rollback of the Proto-Tethyan oceanic slab due to the southward migration of arc magmatism at ca. 440 Ma. The Palaeozoic tectonic evolution and orogen-scale geodynamic processes of the Qinling orogen are thus reconstructed.