Early paleoproterozoic tectono-magmatic evolution of the southwestern yangtze craton delineated by 2.37–2.33 ga granitic-dioritic assemblages in the cuoke complex

Understanding how early Paleoproterozoic tectono-magmatic processes shaped the Yangtze Craton is critical for reconstructing Precambrian cratonization and its role in the assembly of Columbia. However, this history remains enigmatic in the southwestern Yangtze Craton because well-preserved Archean-Paleoproterozoic rocks are scarce. Here we present integrated whole-rock geochemical, zircon U-Pb geochronological, and zircon Hf-O isotopic data for 2.37–2.33 Ga granitoids and diorites from the Cuoke Complex. Our results define four distinct magmatic suites. 2.37–2.35 Ga sodic granites with trondhjemitic affinity exhibit high Na 2 O/K 2 O ratios, low K 2 O and Rb contents, low Sr/Y and (La/Yb) N ratios, and enriched Hf-O isotopic compositions, indicating partial melting of Mesoarchean mafic crust under low- to moderate-pressure conditions. 2.36–2.33 Ga strongly peraluminous granites with S-type affinity display low FeO/MgO ratios and HFSE contents, variable CaO/Na 2 O, K/Rb, and Rb/Sr ratios, and enriched Hf-O isotopic compositions, favoring derivation from a heterogeneous metasedimentary source. 2.35 Ga granites with A-type geochemical affinity show enriched Hf-O isotopic compositions, reflecting high-temperature remelting of compositionally heterogeneous crust involving TTG-like basement and metasedimentary components. 2.35 Ga diorite exhibits low Mg # and Nb/Ta ratios, high Rb/Sr values, and enriched Hf-O isotopic signatures, favoring derivation from partial melting of Mesoarchean mafic lower crust with possible mantle thermal contribution. These magmatic suites record a progressive tectonic transition from late syn -collision to post-collisional extension, likely driven by orogenic collapse, lithospheric delamination, and asthenospheric upwelling, which promoted large-scale reworking of heterogeneous Mesoarchean crust. Synthesis of previous data suggests that a magmatic shift from regional 2.37–2.35 Ga syn -collisional S-type granites and sodic granites to 2.35–2.31 Ga post-collisional granitoids with increasing proportions of A-type affinity and dioritic-mafic rocks likely marks a tectonic switch of the southwestern Yangtze Craton from syn -collision to post-collision at ca. 2.35 Ga. This collisional event was followed by a within-plate tectonic regime from ca. 2.33 Ga and renewed convergence with the northern Yangtze domain after ca. 2.15 Ga, culminating in final craton amalgamation at 2.0–1.93 Ga. The comparable Paleoproterozoic tectonothermal evolution of the Yangtze and North China cratons may further indicate a close geodynamic linkage during the assembly of Columbia.