Genesis and geodynamic implications of Early Cretaceous granitoids in the southern Great Xing’an Range, NE China: The Laodaogou granitic complex

Mesozoic granitoids associated with Sn-Pb-Zn-Ag polymetallic deposits are prominent features in the southern Great Xing’an Range (SGXR), NE China. Understanding the origin and evolution of these granitoids is crucial for deciphering the associated mineralization and geodynamic processes. This study presents geological observations, zircon U-Pb ages, whole-rock major- and trace-element data, and zircon Lu-Hf isotopic analyses of the Early Cretaceous Laodaogou granitic complex in the SGXR. This complex, which hosts the Laodaogou Ag-Pb-Zn-(Sn) occurrence, consists of various types of plutonic rocks, including biotite monzogranites, biotite alkali-feldspar granites, alkali-feldspar granites, and porphyritic alkali-feldspar granitic dikes. Zircon U-Pb dating of these units yields Early Cretaceous ages ranging from ca. 145.3 Ma to 130.6 Ma. The four granite units exhibit broad variations in (K2O + Na2O)/CaO (5.63−56.64), FeOt/MgO (6.85−116.97), 10,000*Ga/Al (2.25−3.09), and Zr + Ce + Nb + Y contents (97.1−274.7 ppm). The elemental results coordinated U-Pb ages indicate that the Laodaogou complex exhibits high degrees of fractionation, evolving from I-type to A-type granites. The granite units show similar εHf(t) values (+7.7 to +16.1) and relatively young Hf model ages (650−165 Ma). It suggests that they were primarily derived from partial melting of a juvenile lower crust originating from a depleted mantle source. In the context of relevant published data, we propose that the retreating subduction of the Paleo-Pacific plate drove the Early Cretaceous magmatism in the SGXR. Asthenospheric mantle upwelling induced partial melting of the juvenile crust within the Central Asian Orogenic Belt, accompanied by magmatic differentiation and shallow emplacement. These processes culminated in regional Sn-Ag-Pb-Zn mineralization within the SGXR.