The Ovor Bayan molybdenum deposit in Mongolia is located within the western segment of the Nukhetdavaa–Erlianhot–Dongwuzhumuqin–Aershan Mo–Pb–Zn–W–Cu–Sn–Cr–Fe metallogenic belt in the Mongolia–Daxing’anling Metallogenic Province. This metallogenic belt lies in the Sino-Mongolian border region, where over ten large-sized deposits have been discovered on the Chinese side in the past two decades. However, the discovered deposits in Mongolia side are relatively small in scale, primarily medium to small-sized, with no large deposits identified to date. Therefore, strengthening research on typical deposits and summarizing metallogenic patterns in this area are the optimal approaches to achieving breakthroughs in prospecting. This study focuses on the Ovor Bayan deposit, a newly identified deposit of molybdenum mineralization within the western segment of the belt. We examine the deposit’s zircon U-Pb geochronology and Re-Os isotopic data. The SHRIMP zircon U–Pb dating of the ore-bearing granite indicates crystallization ages of 183.3 ± 1.9 Ma, which closely align with the mean Re-Os age of 183.1 ± 2.3 MaMa for the Ovor Bayan molybdenum deposit, suggesting an Early Jurassic magmatic event marked by Mo-dominated mineralization coinciding with the extensional tectonic setting following the southeastward subduction-collision of the Mongol–Okhotsk Plate. Regional data indicate that the Nukhetdavaa–Erlian–Dongwuqi–Aershan metallogenic belt experienced concentrated Mo-W mineralization between 240 and 131 Ma. The formation of Mo-dominated deposits, such as Ovor Bayan and Aryn nuur in the western segment of the belt, is at least 50 Ma earlier, which underscores the presence of a significant Mo metallogenic event during this critical post-collision to extensional mineralization period. The molybdenite sample exhibits Re contents ranging from (969.2–1209) × 10⁻⁶, suggesting a mantle-derived source for the molybdenum mineralization.

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.