Deciphering multi-stage W-Sn mineralization at ore-field scale: new U-Pb geochronology and trace element fingerprinting from the world-class Dayu district, Nanling

The Dayu ore field hosts an established reserve of 0.25 Mt WO3 and 0.1 Mt Sn, including the well-known Xihuashan and Piaotang W–Sn deposits, as well as numerous medium-sized deposits, such as Dangping and Muziyuan. However, studies on deposits of varying sizes in the Dayu ore field remain limited, hindering a full understanding of regional ore genesis and constraining the delineation of prospective exploration targets. In this study, we present LA-ICP-MS U–Pb dating and trace-element analyses of wolframite and cassiterite from the Dangping and Muziyuan deposits. Together with ages from the giant Xihuashan and Piaotang deposits, our new robust U-Pb ages define two episodes of W-(Sn) mineralization at the Dayu W-Sn ore field: an earlier event at >160 Ma and a younger event at ~156–155 Ma. We suggest that the cupolas of concealed granites emplaced during the younger pulse at Dangping and Muziyuan are prime targets for greisen-type tungsten mineralization. Wolframite from Dangping and Muziyuan is enriched in Nb and Ta and displays left-inclined trend REE patterns with negative Eu anomalies, indicating wolframite-forming fluids derived predominantly from highly fractionated granites, with limited meteoric water mixing and wall‐rock alteration. High concentrations of Ti, Fe, Zr, and W in cassiterite from Dangping, Muziyuan, and Piaotang further support a predominantly magmatic–hydrothermal origin of the mineralizing fluids. All cassiterite samples show fluctuations in Nb and Ta, reflecting variable temperatures during precipitation. Pronounced Nb and Ta variations in Piaotang cassiterite, coupled with positive Eu anomalies in wolframite, indicate significant meteoric water input during the cassiterite-forming process. In summary, we emphasize the complex ore genesis of different deposits in a single ore field, which may have originated from distinct magmatic events and exhibit markedly different mineralization processes.