Implications for tectono-magmatic evolution and tin mineralization in Tengchong terrane, western Yunnan, China: Evidence from geochemistry and Sr-Nd-Hf isotope of Cretaceous granitoids

The early to late Cretaceous granitoids of the Tengchong terrane offer key insights into the tectonic evolution of the Meso-Tethys and Neo-Tethys Oceans and associated polymetallic mineralization. This study employs petrological, geochemical, and isotopic analyses (Sr-Nd, zircon U-Pb, Lu-Hf) to investigate the Diantan, Guyong, and Xiaolonghe plutons and their tectonic evolution. Zircon U-Pb dating reveals ages of 116.5 Ma for the Diantan granite porphyry, 71.8 Ma for the Guyong biotite granite, 76.5 Ma for the Xiaolonghe monzogranite, and 66.4 Ma for the Xiaolonghe granodiorite. Geochemical data show that the Early Cretaceous granites are S-type, while the Late Cretaceous granites are A-type, reflecting a transition from syn-collisional to post-collisional extension. Negative zircon εHf_(t) values (−3.1 to −14.9) and two-stage model ages (T_DM2 = 1.17–2.03 Ga) indicate incorporation of Mesoproterozoic and Paleoproterozoic crustal material. Sr isotope ratios (initial ⁸⁷Sr/⁸⁶Sr_(i) values ranging from 0.709662 to 0.725917) suggest formation via melting of heterogeneous sources, including igneous and metamorphosed sedimentary rocks. The significant contribution of remelted tin-rich strata and multi-stage fractional crystallization explains variations in ore-bearing properties of the tin-bearing granites at Xiaolonghe and Lailishan. These findings highlight the strong tin mineralization potential of the Tengchong-Lianghe region, driven by multi-phase magmatism and substantial deep-seated tin resources.