Rare metals such as Li, Be, Nb, and Ta are crucial for modern high‑tech industries. The North Qaidam (NQ) region on the northern Tibetan Plateau has recently emerged as an important rare-metal granitic pegmatite metallogenic belt, with several discoveries highlighting its significant potential. Among these, the newly identified Duolongge (DLG) pegmatite in the western part of the belt represents a key Li–Be–Nb–Ta mineralized occurrence. This paper presents a detailed geological, geochronological, and geochemical study of this newly discovered prospect. Petrographic observations reveal three main lithofacies: muscovite-K-feldspar, graphic-textured muscovite-albite, and muscovite-albite granitic pegmatites. The dominant ore mineral is manganocolumbite (Mn‑rich columbite‑tantalite). LA-ICP-MS U-Pb dating of manganocolumbite yielded a crystallization age of 227.8 ± 1.4 Ma (Late Triassic). Geochemically, the pegmatites are strongly peraluminous (A/CNK = 1.51–2.03), exhibit a pronounced rare-earth-element tetrad effect, and are enriched in light rare‑earth elements (0.97–15.49 × chondrite) and incompatible elements such as Cs, Rb, Nb, Ta, Zr, Hf, showing an affinity to the LCT family. Zircon ε Hf (t) values range from –2.87 to + 2.97, with two-stage Hf model ages (T DM2 ) of 921–1227 Ma, indicating a dominant source from partial melting of Mesoproterozoic ancient continental crust with a minor mantle contribution. Integrated with previous studies, the geochronological data from the DLG pegmatite reveal that it shares an identical Late Triassic emplacement age with most rare-metal pegmatites in the eastern NQ, all formed in a post-collisional extensional setting following the closure of the Paleo‑Tethys Ocean. More importantly, the DLG prospect is located approximately 270 km west of earlier-discovered deposits such as Chakabeishan, confirming that the rare-metal pegmatite belt extends continuously across the NQ. This finding substantially expands the recognized spatial distribution and exploration potential of rare-metal pegmatites in the region.
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