Early Paleozoic orogenic belt in the eastern segment of South China

The authors performed a systematic study of the Early Paleozoic belt in the eastern segment of South China, including its sedimentary environment, volcanic rocks, ages of mafic-ultramafic rocks, kinematic analysis of ductile deformation and orogenic mechanism. Results suggest that the Sinian-Ordovician sequence (680-440 Ma) consists chiefly of sandstone and mudstones. In the strata neritic sedimentary structure is well developed, without the Bouma sequence, volcanic lavas or explosive pyroclastic rocks. Some originally defined Early Paleozoic basalt is actually graywacke. Based on the aforesaid study, combined with the geochemical features of graywacke, the study area was a neritic-bathyal environment on the passive continental margins during the Early Paleozoic. SHRIMP U-Pb zircon dating of some mafic rocks and volcanic rocks show that their ages cluster at 860-800 Ma. The kinematic pattern of ductile deformation indicates that the southeastern foot of the Wuyi Mountains was overthrust from northwest to southeast, while the northern foot was thrust from south to north, displaying a flower-shaped structural style is displayed in section. Slightly later, strike-slip shearing occurred. The 40Ar-39Ar dating of muscovite and biotite from mylonitic yielded ages in the range from 430 to 390 Ma. By comparing with the typical Caledonian orogens in the world, the Early Paleozoic South China orogenic belt shows distinct local features and the orogenic mechanism is similar to that of the Pyrenean orogenic belt of Western Europe.