Radioactive and Spectral Characteristics of the Qiongjiagang Pegmatite-Type Lithium Deposit in the Himalayas and Their Significance of Ore Prospecting

Lithium resources play a crucial role in the new energy industry, and their efficient exploration is directly related to the safety and stability of the new energy industrial chain. Pegmatite-type lithium deposits have become one of the main sources of lithium resources due to their high grade and ease of exploitation. The Qiongjiagang mining area hosts the first industrially valuable pegmatite-type lithium deposit discovered in the Himalayan metallogenic belt. Previous studies have extensively investigated its geochemistry and geophysical prospecting; however, the radioactive and spectral characteristics of the pegmatite-type lithium deposits in this area remain unclear, which limits the effective application of remote sensing technology. This study investigates the radioactive and spectral characteristics of pegmatite-type lithium deposits in the Qiongjiagang mining area of the Himalayas, explores applicable remote sensing identification methods, and establishes a dual-indicator identification method based on radioactive and spectral characteristics to achieve rapid and accurate identification of spodumene-bearing pegmatites. An environmental X and γ radiation detector, an X-ray fluorescence spectrometer, and a hyperspectral ground object spectrometer were used to conduct field radioactive measurements, radioactive element content measurements, indoor spectral test analysis, and mineral composition detection of various rocks. The results show that the radioactive characteristics of various rocks in the area follow the order: pegmatite > granite > surrounding rock (marble) > other rocks, with pegmatite exhibiting obvious thorium (Th) anomalies. In terms of spectral characteristics, the wavebands of 1900 nm, 2200 nm, and 2480–2490 nm possess diagnostic features for ore prospecting, which can be used to effectively distinguish spodumene-bearing pegmatites, non-ore-bearing pegmatites, and surrounding rocks. In addition, the reflectance of various rocks generally follows the sequence: ore-bearing pegmatite > non-ore-bearing pegmatite > granite > surrounding rock (marble). The range of radioactive characteristics of various rocks in the Qiongjiagang mining area and the prospecting indicator wavebands for ore-bearing pegmatites has been obtained, the radioactive and spectral characteristics of pegmatite-type lithium deposits in the area has been revealed, and an identification method based on dual indicators has been proposed, thereby achieving the goal of convenient and efficient ore prospecting.