Abstract Collisional orogeny is characterized by deep subduction of continental crust and major crustal thickening, leading to high-pressure/high-temperature metamorphism and anataxis of the subducted continental crust. Since conductive heating of large slabs of cold, subducted continental crust is a slow process, heating to a temperature that is high enough to generate significant partial melting can take tens of millions of years. Where the spatial and temporal relationships are obscured due to later modification (e.g. post-collisional rifting), the peak metamorphism and magmatism may be interpreted as an orogeny that is separate from the collision, or may be interpreted as an intraplate orogeny as no contemporaneous arcs or ophiolite may be present. We propose here that this is the case for the early Paleozoic orogeny in South China. In our model, the West Cathaysia terrane of South China was part of a continent (possibly Australia) on the lower plate and collided with another continent (possibly India) in the Cambrian–Ordovician, at a late stage of Gondwana assembly, and the late Ordovician–Silurian Wuyi–Yunkai orogeny, characterized by amphibolite–granulite facies metamorphism and extensive anataxis, was a continuation of the Cambrian–Ordovician collisional orogeny. In this interpretation, the Wuyi–Yunkai orogen was part of the Kuunga orogen before Gondwana break-up.

Abstract The Early Paleozoic Orogeny in eastern South China has been highly controversial. It has been alternatively interpreted to have formed in an intra-plate setting driven by far-field tectonic forces or at plate boundaries involving subduction–collision. The West Cathaysia terrane in the core of the orogen is characterized by extensive magmatism, intense deformation and especially high-grade metamorphism. Identifying early Paleozoic high-pressure (HP) metamorphism and establishing a complete P–T–t path from the high-grade metamorphic rocks could help us understand the tectono-thermal evolution process and nature of the Early Paleozoic Orogeny. Here, we present results from a felsic granulite from the Chencai Complex in the northeastern West Cathaysia terrane. Petrographic evidence, mineral compositions and phase equilibria modelling indicate that the granulite underwent a pre-peak HP stage with P–T conditions of 13.3–14.7 kbar/696–718°C and low geothermal gradients of 13–14°C km −1 , and a peak high-temperature stage with P–T conditions of 9.7–11.0 kbar/785–820°C. A clockwise P–T path involving pre-peak decompressional heating, post-peak near-isothermal decompression and near-isobaric cooling processes was constrained for the HP felsic granulite. In situ monazite U–Pb geochronology combined with previous results date these metamorphic processes at c. 440, c. 425 and c. 400 Ma, respectively. Our new metamorphic and geochronological data from the HP felsic granulite support the case that the Early Paleozoic Orogeny was a typical collisional one.