To investigate the evolution of the continental lithosphere of the southwestern South China Block, this study compiled previously whole-rock major and trace elements (n=76), whole-rock Sr-Nd-Pb isotopes (n=54) and in-situ zircon Hf isotopes data (n=113) of late Cretaceous Gejiu alkaline complex in South China Block, to reconstruct the geochemical signature and petrological model.According to its geochemical characteristics of the alkaline complex, which can be divided into three groups. Group one, shoshonitic nepheline syenites that show notably high total alkali (12.76%~17.57%) and total REE contents (134×10^-6~1 764×10^-6), low Ba/La ratios, and enriched Sr-Nd-Pb-Hf, indicating the enriched lithospheric mantle metasomatized by subduction-related melts. Group two, shoshonitic monzogabbro-monzonite suite has strongly high Ba (1 619×10^-6~4 640×10^-6) and Sr (970×10^-6~1 690×10^-6)contents, low Th/Yb ratios, similar to Sr-Nd-Pb-Hf isotopic components in nepheline syenite, indicating the enriched lithospheric mantle metasomatized by subduction-related fluids.Group three, monzogranite-K-feldspar granite suite shows high Th (30.7×10^-6~68.3×10^-6)and U (4.11×10^-6~23.2×10^-6) contents, and consistently Nb/U ratios of the lower crust and its trace element characteristics, indicating that they could be derived from the lower crust at variable depth. The MME and mantle-derived geochemical signatures are very developed in monzogranites, which indicate that their sources have experienced mantle-derived magma injection and crust-mantle magma mixing.During the Late Cretaceous, the South China Block occurred the lithospheric extension in the east-west direction that was influenced by the Neo-Tethys tectonic system, then the upwelling of asthenosphere material resulted into the reworking of the lithosphere, where a large amount of mantle-derived magma was injected into the lower crust and supported continental crust growth.

Zircon is ubiquitously distributed in magmatic, metamorphic, and sedimentary rocks of the solid Earth. Owing to its exceptional stability under high temperatures and weathering conditions, zircon preserves critical information about the crystallization age, temperature, oxygen fugacity, and geochemical characteristics of its host rocks, making it a vital tool for studying petrogenesis and deep Earth processes. This paper provides a preliminary analysis of recent advances in zircon applications for petrogenetic research. Zircon contains abundant radioactive isotopes and their stable decay products. Notably, the decay of ²³⁸U to ²⁰⁶Pb, ²³⁵U to ²⁰⁷Pb, and ²³²Th to ²⁰⁸Pb enables the U-Pb isotopic decay system to serve as the most reliable method for determining the crystallization age of zircon-bearing rocks. Additionally, the decay of ¹⁷⁶Lu to ¹⁷⁶Hf in zircon allows the Lu-Hf isotopic system to effectively trace the magma source regions of host rocks. Meanwhile, the oxygen stable isotopes (δ¹⁸O) in zircon faithfully record the oxygen isotopic signature of its source, providing insights into the crustal or mantle affinity of the parental material. The recently developed zircon Zr stable isotope system offers novel perspectives for understanding magmatic processes, such as tracking felsic magma differentiation and dynamic magma evolution. Furthermore, trace elements (e.g., Ti, Ce, Eu) within the zircon lattice can be utilized to construct thermometers and oxygen fugacity sensors, quantitatively constraining physicochemical parameters like crystallization temperature and redox conditions. Methods based on zircon isotopic systems (U-Pb, Lu-Hf, O, Zr), thermometers, and oxygen fugacity meters have played a significant scientific role in petrogenetic studies. As a robust scientific medium, zircon remains indispensable for geoscientists and will continue to address fundamental questions in Earth and planetary sciences, from crustal evolution to magmatic dynamics.