Objective The Sandun Cu−Pb−Zn deposit is a large deposit newly discovered in the northeastern Hunan region during the geological survey, which is located in the southern margin of the Mufu Mountain pluton. It belongs to the magmatic hydrothermal filling metasomatic vein type deposit, whose metallogenic age is unknown.

Methods Based on detailed field geological investigation, sulfide−fluorite−quartz vein of the Sandun Cu−Pb−Zn is Sm−Nd, Pb isotope studied in this paper.

Results The isochron age obtained from fluorite Sm−Nd isotope dating is 88.8±2.4 Ma (MSWD = 1.3), indicating that the mineralization age belongs to the Late Cretaceous, which is significantly later than the formation age of the known magmatic activity in this area. The ε_Nd(t) value of the Sm−Nd isotope composition of fluorite is −9.1±0.1, and the initial ratio of ¹⁴³Nd/¹⁴⁴Nd is 0.512059±0.000005. The sulfide Pb isotope of ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb ratios are 18.128~18.452, 15.574~15.849, and 38.440~39.004, respectively, indicating that the ore−forming materials of this deposit may mainly originated from deep magmatism.

Conclusions The aforementioned characteristics suggest that the potential presence of Late Cretaceous concealed rock masses in this region, which has significant guiding importance for regional prospecting and exploration.