Petrogenesis of the Dupangling Granitic Complex, South China: Implications for A-type and Strongly Peraluminous Granite Origin

Abstract

Granite origin is crucial to understanding the evolution of continental crust, yet many concerns about granite genesis remain yielding ongoing debates. A new integrated study of petrology, geochronology, mineral chemistry and whole-rock geochemistry of the Dupangling granitic complex in South China, indicate that the granites in the western complex were emplaced during the Caledonian (418 Ma); they have SiO₂ contents of 68.1–70.4 wt%, and are calc-alkaline and strongly peraluminous with high maficity [(TFe₂O₃ + MgO) > 4.0 wt%] and exhibit ⁸⁷Sr/⁸⁶Sr(t) of 0.7234–0.7311 and ε_Nd(t) of –9.0 to –6.7. The granites in the eastern complex, emplaced during the Indosinian (212 Ma), have high SiO₂ contents (73.3–79.8 wt%) and exhibit affinities with A-type granites, such as enrichment in alkalis and rare earth elements (REEs), and depletion in Sr and Ba along with high TFeO/(TFeO + MgO), Ga/Al and Zr + Y + Ce + Nb; these granites exhibit ⁸⁷Sr/⁸⁶Sr(t) of 0.7221 and ε_Nd(t) of –9.2 to –7.5. Geochemical characteristics suggest that the older Caledonian granites were derived through dehydration melting of Paleoproterozoic metasedimentary rocks plus additional (∼20%–32%) input from mafic magma, whereas the Indosinian granites were generated through shallow dehydration melting of the Caledonian granitoids.