Study on the Spectral Identification Characteristics of Typical Rocks and Minerals in Alkali Feldspar Granite Type Nb-Ta Deposits in Central Inner Mongolia

Located in the central region of Inner Mongolia, within the southern segment of the Daxing'anling–North China Craton metallogenic belt, the area is notable for its widespread distribution of alkaline granite-type niobium-tantalum (Nb-Ta) deposits. Despite the region's rich Nb-Ta resources, a comprehensive understanding of their spectroscopic characteristics remains inadequate, hindering precise and efficient mineral exploration. This study focuses on the Zhaojinggou large Nb-Ta deposit, employing portable short-wave infrared and thermal infrared spectrometers to analyze typical rock and mineral samples. The research reveals distinctive spectroscopic features of Nb-Ta enriched alkaline granite, Tianhe petrochemical sodic granite, Tianhe leucogranite, biotite two-mica granite, and quartz veins containing scheelite. Comparative analysis, particularly against the standard sodium granite spectrum from the USGS spectral library, identifies a specific weak absorption feature at 2360nm crucial for distinguishing Tianhe petrochemical sodic granite from other rocks and minerals, likely attributed to rock alteration and mineralization processes. In thermal infrared spectroscopy, quartz veins containing scheelite are distinguished by their high reflectance and “three-peak” features. Despite spectral similarities among Nb-Ta enriched alkaline granite, Tianhe leucogranite, and Nb-Ta enriched alkaline granite, differences in absorption depth around 2200nm and the IC for effective mineral differentiation. These findings provide a foundational dataset for future remote sensing surveys and evaluations of Nb-Ta mineral resources. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202401090001.