Tracing Rodinia’s assembly to breakup: Insight from Mesoproterozoic to Neoproterozoic granites along the western margin of the Yangtze Block (Southwest China)

Understanding the tectonic evolution of the Yangtze Block during the late Mesoproterozoic and Neoproterozoic is crucial for gaining insights into the assembly and breakup of the Rodinia supercontinent. Here, we present an integrated geochronological, whole-rock geochemical, and Nd-Hf isotopic study of the late Mesoproterozoic Shuiqiaosi (ca. 1104−1045 Ma) and mid-Neoproterozoic Yaoxingcun (ca. 768 Ma) granites of the Xujie area, central Yunnan Province, China. Our investigations focus on their petrogenesis and tectonic setting, aiming to constrain the evolution of the supercontinent. The Shuiqiaosi granites are A2-type granites, with positive whole-rock εNd(t) (0.0−1.5) and zircon εHf(t) (3.9−17.5) values, indicating derivation from the partial melting of juvenile crustal rocks. In contrast, the Yaoxingcun granites exhibit an S-type affinity, with negative whole-rock εNd(t) (−5.8 to −4.6) and variable zircon εHf(t) (−3.0 to +8.7) values, suggesting origination from the partial melting of Al-rich, metasedimentary sources with some involvement of mantle materials. Combined with results from previous studies in the western Yangtze Block, we propose that the Shuiqiaosi A-type granites and Yaoxingcun S-type granites—both of which exhibit high-temperature features—are related to the assembly and breakup of the Rodinia supercontinent, respectively. Based on the ultramafic-mafic and felsic rocks examined in previous studies, we further suggest that the western margin of the Yangtze Block was situated in a subduction-related extensional setting during ca. 1.1−1.0 Ga, which marked the assembly of Rodinia. The breakup of Rodinia began at ca. 0.83 Ga, driven by a mantle plume, with specific regions, including the study area, experiencing slab tearing or breakoff in an oceanic subduction environment during ca. 0.80−0.75 Ga.