Contrasting behavior of platinum-group elements and Au-Cu during mantle melting and refertilization: Implications for lithospheric metal fertility

Mounting evidence highlights the critical role of silicate-melt−mediated refertilization in lithospheric evolution, yet chalcophile element behavior during this process remains contentious. Integrating Pyrenean peridotite geochemistry (of the Lherz massif) with quantitative modeling reveals that platinum-group elements (PGEs), due to their extreme sulfide compatibility, are primarily controlled by initial partial melting, and largely unaffected (or net addition strictly localized at the reaction interface) by refertilization. Conversely, moderately incompatible Cu and Au are systematically enriched overall in the mantle column during refertilization. This decoupling is globally corroborated, where pervasive Au-Cu enrichment characterizes both subcontinental lithospheric mantle (SCLM) and oceanic lithospheric mantle (OLM), while systematic platinum-palladium depletion in SCLM versus primitive mantle−like ratios in OLM reflect distinct sulfide exhaustion during their partial melting. Crucially, the eastern North China craton exemplifies how extensive refertilization transforms ancient, barren SCLM into a fertile Au-Cu and volatile-rich source, directly supplying the ingredients for giant Au deposits. This provides a quantitative framework linking mantle processes to lithospheric metal fertility.