Prospecting Prediction of the Tieyaoshan Tin Deposit Based on Zircon U–Pb Geochronology, Geochemical Data and Tectonic Numerical Simulation

This study integrates zircon U–Pb geochronology, whole-rock geochemical analysis, and tectonic numerical simulation to determine the emplacement age, petrogenesis, and tectonic setting of ore-bearing granites in the Tieyaoshan tin deposit and further clarify the structural ore-controlling characteristics to provide effective geological evidence and favorable prospecting indicators for tin deposit prediction in the study area. The Tengchong block is located in the Sanjiang–Tethys tectonic domain. The Tieyaoshan deposit is situated at the southwestern end of the regional metallogenic belt and belongs to the Early Cretaceous Donghe granite belt, with ore-bearing lithology dominated by medium-fine grained biotite granite. Zircon U–Pb dating yielded a precise emplacement age of 123.45 ± 0.64 Ma for the ore-related granite. Geochemically, these granites are enriched with sodium and potassium. In comparison to the primitive mantle, the rock samples exhibit a marked enrichment in large-ion lithophile elements (LILEs). Additionally, there are distinct negative anomalies in typical high-field-strength elements (Nb, Ta, P, Ti). The analysis of major and trace element discrimination diagrams collectively suggests that the granites originated in a tectonic setting characterized by subduction-collision and subsequent post-collisional extension. The consistent geochronological and geochemical signatures between the ore district plutons and the igneous rocks from the central and eastern Lhasa block demonstrate that the Early Cretaceous Tengchong magmatic belt represents the southeastern extension of the central Lhasa magmatic belt, which was a magmatic response to the subduction and collision of the Meso-Tethyan oceanic crust beneath the Lhasa–Tengchong block along the Bangong Co-Nujiang suture zone. Tectonic stress field numerical simulation reveals that the study area is dominated by NW–SE compressive stress, and the central region exhibits obvious shear stress concentration, which accounts for widespread rock fragmentation and well-developed structures. During the mineralization period, shear stress was predominantly concentrated along the NE-trending fracture structures. Therefore, the NE-trending fracture zones formed during mineralization, together with the early-stage E–W-trending guiding and host structures, constitute favorable metallogenic spaces. This study provides important theoretical guidance for tin ore prospecting in the region.