Contrasting granites associated with W, Sn, and Be mineralization in the Xuebaoding and Pingwu areas, Sichuan Province, SW China

Rare metals (e.g., tungsten, tin, or beryllium) are critical strategic elements mainly hosted by magmatic-hydrothermal ore deposits associated with granitic intrusions. The simultaneous occurrence of W, Sn, and Be is unusual, and the underlying processes leading to the formation of corresponding ore deposits is not yet understood. In that regard, the Xuebaoding W-Sn-Be deposit in the Songpan-Garze Orogenic Belt of western China stands out with its exceptionally high Be content with only weak alteration. While the Xuebaoding deposit has been the subject of much previous petrographic, geochronological, mineralogical, and ore-forming fluid investigations, few studies have yet addressed the regional granitoid rocks around the deposit and their potential association with the Xuebaoding system. Here, a contrasting lithologic, geochemical, chronological, and Sr-Nd-Pb isotope analyses of granites from neighboring intrusions with only W mineralization near Pingwu is performed. The Pingwu granites are found to be S-type, of 211.4 +/- 0.7 to 229.8 +/- 0.6 Ma age, with high A/CNK values (>1.07), and Sr-Nd-Pb isotope values of Sr-87/Sr-86((i)) = 0.70589-0.71486, epsilon Nd-(t) = -3.49 to -9.51, Pb-206/Pb-204 = 17.9378-18.3996, Pb-207/Pb-204 = 15.5693-15.6836, and Pb-208/Pb-204 = 38.1382-38.7390. In addition, these granites are low in W (0.06-4.1 ppm), Sn (1.0-7.3 ppm) and Be (1.6-8.6 ppm). A comparison with the Xuebaoding granites suggests a cogenetic origin, but a lower degree of fractionation in the Pingwu system. The different petrogenesis of the W occurrences near Pingwu with respect to the W-Sn-Be deposit are likely due to a combination of protolith, melting mechanism, and ore-controlling structures. The work highlights the unusual conditions necessary for the spatial or temporal coexistence of W, Sn, and Be mineralization within the same deposit as represented by only few deposits worldwide.