Geochemical Characteristics of Ore-forming Intrusions and their Diagenetic and Metallogenic Revelation from the Xiataolegai Iron and Copper Deposit, Inner Mongolia

The Xiataolegai iron and copper deposit, located in Inner Mongolia, is a representative skarn-type deposit within the active continental margin of the Beishan Metallogenic Belt. Situated in the western part of the Ejina Banner in the Alashan League, it is closely associated in both time and space with granodiorite and monzogranite linked to Fe-Cu mineralization. To ascertain the formation age, source characteristics, and the relationship between magmatism and mineralization, samples underwent petrography, geochemical analysis, and zircon U-Pb dating. Results reveal high SiO₂, Al₂O₃, alkalinity, and low MgO, with LREE enrichment and HREE depletion in both granodiorite and monzogranite. Granodiorite exhibits Rb, La enrichment, Ta, Nb, Ti, P depletion, weak Ce positive and Eu negative anomaly, while monzogranite shows Rb, U enrichment, Nb, Ti, P depletion, Ce positive and weak Eu negative anomaly Both granodiorite and monzogranite are classified as calc-alkaline I-type granite. The obtained U-Pb ages for zircons from granodiorite and monzogranite are (451.7±4.8)Ma and (460.1±4.9)Ma, indicating that the magmatism and related mineralization in the eastern and western section of the deposit occurred in the Late Ordovician and Middle Ordovician, respectively. A comprehensive analysis suggests that the Xiataolegai deposit formed in the late-middle Ordovician within an active continental margin arc tectonic setting, likely associated with oceanic plate subduction.