Gold fertilization driven by volatile-rich lithospheric mantle metasomatism: Insights from syn-metallogenic magmatism in the Jiaodong Peninsula, eastern North China Craton

The mantle fertilization processes driven by subduction associated with gold mineralization are critical yet remain poorly understood in the world-class Jiaodong gold province, where more than 5000 tons of Au formed within a unique decratonization setting. We conducted integrated geochronological and geochemical analysis from newly discovered syn-mineralization diorites and pre-mineralization granodiorites at the Xiadian gold deposit, NW Jiaodong Peninsula, both of which are spatially associated with gold ores. Zircon U−Pb dating reveals ages of ca. 125 Ma for the Guojialing granodiorite and 121 Ma for the diorite, nearly coinciding with gold mineralization events (ca. 120 Ma). Our data, including inherited zircons from the lower crust of the North China Craton (NCC), mantle-derived apatite signatures consistently indicate that the Guojialing granodiorite was derived from the mixing between the melts derived from the lower crust of the NCC and asthenospheric mantle. In contrast, the Xiadian diorite displays geochemical characteristics including depletion of high field strength elements, heavy rare earth elements and lithospheric−mantle-like apatite Sr−Nd isotopic signatures, alongside inherited zircons from the Yangtze Craton crust, indicating a source of metasomatized subcontinental lithospheric mantle (SCLM) of the NCC. Building on this, the apatite trace element−based machine learning model developed from the global gold-fertility dataset indicates that the source of gold fertility is the enrichment of volatile-rich mafic components. This is reflected in our data by the enrichment of water, S, Cl (and potentially Au) of the mantle source of the Xiadian diorite, as well as its elevated oxidation state. This gold fertility was inherited from earlier subduction-related devolatilization and subsequently reactivated during later asthenospheric upwelling. As the SCLM began to melt, gold that had been enriched within the lithospheric mantle was mobilized and released, with the transient remobilization triggered during the rollback of the subducted slab leading to the formation of large-scale gold mineralization.