Objective The Lalangmai tungsten deposit is a significant and the only discovery in recent tungsten exploration in the eastern part of the East Kunlun Orogen. Its timing of mineralization is similar to that of the Silurian Baiganhu tungsten−tin ore district in the western part. Understanding its metallogenic mechanism is crucial for revealing regional tungsten−tin metallogenic patterns and guiding future exploration efforts.

Methods This study systematically investigates the geological characteristics of mineralization, geo−chronology , and metallogenic mechanism of the Lalangmai tungsten deposit through geological fieldwork, petrographic observations, whole−rock geochemistry, Sr−Nd isotope analysis of the whole rock, and Sm−Nd isotopic dating of garnet and scheelite.

Results Tungsten mineralization at the Lalangmai deposit is primarily hosted within skarns at the contact zone between monogranite and carbonate wall−rocks. The main ore mineral is scheelite, with gangue minerals including garnet, epidote, diopside, and calcite, characteristic of skarn−type deposits. The monogranite, closely related to mineralization, contains primary muscovite and garnet. It exhibits high silicon, alkali, and aluminum content, with relatively low magnesium and iron. It is enriched in large−ion lithophile elements (LILEs) and depleted in high−field strength elements (HFSEs), and its rare earth element (REE) distribution curve is right−inclined with a distinct negative Eu anomaly, indicating typical S−type granite characteristics. Whole−rock Sr−Nd isotopic data reveal high (⁸⁷Sr/⁸⁶Sr)_i values (0.7470 to 0.7659) and negative ε_Nd(t) values (−8.22 to −6.05). Sm−Nd isotopic isochron dating of garnet and scheelite from the skarn gives an age of 408±4 Ma, which is consistent with the zircon U−Pb age of the monogranite (414±3 Ma) within the margin of error.

Conclusions The study indicates that during the Silurian in the eastern East Kunlun Orogen, the underplating of magmatism led to partial melting of the ancient crust, forming a tungsten−rich S−type granitic magma. Following intrusion, the magma interacted with carbonate strata, resulting in metasomatic replacement and the formation of the Lalangmai skarn−type tungsten deposit.