Alteration mapping and prospecting model construction in the Tiegelongnan ore deposit of the Duolong ore concentration area, northern Tibet, based on shortwave infrared technique

The discovery of the Rongna deposit was a breakthrough in 2013. This deposit was considered as the porphyry-epithermal type deposit, because alteration minerals occur in the surface rock samples which were measured by shortwave infrared and geochemical technique; nevertheless, they are mainly muscovite and chlorite. These minerals form a characteristic alteration system from the outer phyllic to propylic zone. The measuring of the drill cores ZK0804, ZK1604, ZK2404, ZK3204 with the instrument ASD revealed that abundant minerals like alunite, kaolinite and muscovite are existent and coexist with copper. From ZK804 to ZK3204, the abundance of alunite decreases and disappears in ZK3204, but muscovite increases. The combination characteristics of alteration minerals can illustrate the deposit type characterized by the transition from epithermal deposit to porphyry deposit. According to the surface and underground mineral distribution of rock samples, a model about porphyry-epithermal deposit was constructed on the basis of shortwave infrared technique which shows the spectral and type variations of minerals and distribution features. The result obtained by the authors is a good reference for the prospecting with the shortwave infrared technique.