Abstract: The Shilu large-scale Cu-Mo skarn deposit in western Guangdong is situated along the northwestern margin of the Yangchun basin within the Yunkai area. The orebodies are predominantly hosted in skarn and skarnized marble at the contact zone between Early Cretaceous granodiorite and Lower Carboniferous strata, structurally controlled by NE-trending faults. To better understand the metallogenic processes, this study employs EPMA and LA-ICP-MS in-situ microanalysis methods, focusing on garnet and vesuvianite to investigate their elemental geochemical characteristics based on detailed detailed geological investigations. Analytical results demonstrate that: Garnet in the Shilu deposit is predominantly andraditic (Gro0-36And63-100), while pyroxene is overwhelmingly diopside (Hed0-14Jo0-6Di81-99); The mineral assemblage indicates early-stage fluid evolution occurred under high oxygen fugacity conditions;  Vesuvianite exhibits more complex compositions, primarily belonging to common vesuvianite with minor Al-rich, Mg-Al, and Mg-Fe varieties. Garnet formed in a weakly acidic, open-system environment characterized by high water/rock ratios and dominantly infiltrative metasomatism. Both garnet and vesuvianite mainly originated from magmatic-hydrothermal fluids associated with granodiorite and quartz diorite. During the transition from skarn to retrograde alteration stages, the fluid composition shifted from Fe3+-rich to Al-rich, accompanied by significant reduction in w(∑REE). This trend reflects changing physicochemical conditions (e.g., pH) and suggests the involvement of external fluids (e.g., meteoric water) into the open-system alongside magmatic fluids. Additionally, the study identifies considerable tungsten exploration potential but limited tin mineralization potential in the deposit.

Key words: skarn; , garnet, pyroxene, vesuvianite, mineral geochemistry, ore-forming fluids, Shilu Cu-Mo deposit, Yunkai area