Geochronology of the Ulaan Uul W deposit, Northwestern Mongolia: Constraints from zircon U–Pb and wolframite Sm–Nd dating

The Mongolian Ulaan Uul Tungsten Deposit is located in the southern segment of the Altai Cu-Pb-Zn-W-MoNi-Au-Ag-Sb-Co-Fe Metallogenic Belt. The metallogenic belt is situated in the border area of China, Russia, Mongolia, and Kazakhstan, where over 40 large-sized deposits have been discovered. Among these, only one large-sized deposit is found on the Mongolian side, while the others are medium or small in size. Therefore, strengthening the study of typical deposits and summarizing the metallogenic rules of this region is the best way to achieve a breakthrough in mineral exploration of Altai region in Mongolia. This study focuses on the Ulaan Uul W deposit, a newly identified deposit of Tungsten mineralization within the southern segment of the belt. We examine the deposit’s zircon U-Pb geochronology and Sm-Nd isotopic data. The LA-ICP-MS zircon U–Pb dating of the ore-bearing alkali feldspar granite indicates crystallization ages of 212.5±2.2 Ma, which closely align with the wolframite Sm-Nd isochron age of 211.2±1.5 Ma for the Ulaan Uul W deposit, suggesting an Late Triassic magmatic event marked by W-dominated mineralization coinciding with the extensional tectonic setting following the subduction-collision of the Tarim Craton and the Altai Orogenic Belt. Regional data indicate that the Altai metallogenic belt experienced concentrated W mineralization between 242 and 211 Ma. The formation of W- dominated deposits, such as Ulaan Uul in the southern segment of the belt, is at least 30Ma later, which underscores the presence of a significant W metallogenic event during this critical post-collision to extensional mineralization period.