Petrogenesis and Geodynamics of the Early Paleozoic Tangwan Leucogranites, the Wuyi Region of the Cathaysia Block, SE China

Early Paleozoic leucogranites are rare in SE China, and their petrogenesis remains controversial. Here we present zircon U–Pb ages, Lu–Hf isotopes and whole-rock geochemical data for the Tangwan leucogranite in the Wuyi region of the Cathaysia Block to constrain its origin and geodynamic setting. The Tangwan leucogranite was emplaced at approximately 438 Ma. The relatively high Nb/Ta (8.39–9.32), Zr/Hf (28.6–31.8), K/Rb (130–247) and Eu/Eu* ratios (0.47–0.68), together with low TE1,3 values (0.97–1.04), indicate that the Tangwan leucogranite is not a highly fractionated granite. The low Zr + Nb + Ce +Y contents (<200 ppm) and Ga/Al ratios (<2.5) but high A/CNK ratios (>1.2), the presence of muscovite and the absence of mafic melanocratic minerals collectively point to an S-type affinity. The enriched Nd–Hf isotopic compositions, relatively high Rb/Sr ratios (>2), moderate TLREE and TZr values (699–794°C), and low TiO2 contents (<0.2 wt %) suggest derivation from ancient metasedimentary rocks sources via muscovite dehydration melting. The weakly differentiated early Paleozoic leucogranites in SE China formed in a syn-collisional compressional regime, whereas highly differentiated leucogranites record the post-collisional extension driven by mantled-derived magma underplating that supplied sufficient heat.