Sericite Rb-Sr age of the Dongtaozikou gold-molybdenum deposit in the Jialu Area, Xiaoqinling, and its geological implications

The Xiaoqinling region, as the second-largest gold producer in China, is rich in mineral resources. However, the lack of robust metallogenic age constraints has hindered the understanding of ore genesis and regional metallogenic patterns. In recent years, significant deep exploration progress has been made in the Jialu area of the western Xiaoqinling, where the newly discovered Dongtaozikou gold-molybdenum deposit is characterized by intense potassic alteration and a distinctive gold-molybdenum paragenesis, distinctly different from the traditional quartz-vein gold deposits and alteration-type gold deposits dominated by sericitization in the region. Based on detailed field geological surveys and petrographic observations, this study conducted in situ micro-scale Rb-Sr isotopic geochronological analysis on hydrothermal sericite closely associated with gold-molybdenum mineralization in the Dongtaozikou deposit. Two sericite samples yielded Rb-Sr isochron ages of 140 ± 6 Ma and 141 ± 6 Ma, indicating an Early Cretaceous mineralization age. Integrated with regional tectonic-magmatic events, this study proposes that the formation of the Dongtaozikou gold-molybdenum deposit is closely related to crust-mantle interaction under large-scale lithospheric extension and thinning of the North China Craton, triggered by the subduction of the Paleo-Pacific Plate during the Early Cretaceous. Deep-sourced fluids enriched in ore-forming elements migrated upward along ore-controlling structures such as the Xunmadao Fault under regional extension and precipitated at sites of abrupt physicochemical changes. This study not only provides precise geochronological constraints for gold-molybdenum mineralization in the western Xiaoqinling and reveals its unique metallogenic geodynamic setting but also highlights the significant exploration potential in the deep sections of the Xunmadao Fault zone. The findings are of great importance for advancing gold metallogenic theory along the southern margin of the North China Craton and guiding regional mineral exploration.