Evidence for arc-related extension on the periphery of Rodinia: First report of Neoproterozoic magmatism in the South Yellow Sea, China

Abstract

Understanding the dynamic linkage of Neoproterozoic extension-related magmatism between the Yangtze Block and the Gyeonggi Massif in central Korean Peninsula is crucial for reconstructing the paleogeographic evolution of East Asia during the breakup of Rodinia. The South Yellow Sea Basin, positioned between these regions, provides a key window for addressing these questions. This study systematically investigates newly discovered Neoproterozoic granites from the South Yellow Sea, integrating geochronological, geochemical, and isotopic data with published records from the Yangtze Block and the Gyeonggi Massif to decipher the origins and tectonic implications of Neoproterozoic extension-related magmatism within these blocks. The basement granites from the South Yellow Sea, dated to ca. 813–804 Ma, exhibit geochemical characteristics typical of A₂-type granites and are coeval with ca. 830–790 Ma A₂-type granitic magmatism in the Yangtze Block and Gyeonggi Massif. Geochemical and isotopic evidence suggests that most A₂-type granites in these regions originated from the partial melting of Paleoproterozoic metasedimentary rocks, with minor crust-mantle interaction and significant fractional crystallization. Some A₂-type granites in the Gyeonggi Massif, however, were derived from the melting of Paleoproterozoic mafic lower crust. These findings indicate that the ca. 830–790 Ma A₂-type granitic magmatism was closely associated with continent arc extension, likely triggered by slab rollback. The South Yellow Sea and Gyeonggi Massif likely represent the eastern extension of the Yangtze Block, forming part of a marginal arc system along the periphery of Rodinia. This study provides new insights into the Neoproterozoic magmatic-tectonic evolution of East Asia and its paleogeographic configuration during the breakup of Rodinia.