Porphyry Copper Deposit Prognosis in the Middle Region of the Bangonghu–Nujiang Metallogenic Belt, Tibet, Using ASTER Remote Sensing Data

Abstract

The Bangonghu–Nujiang metallogenic belt is considered to be Tibet’s third copper belt after the Yulong and Gangdese copper belts. The Duolong gold-rich porphyry copper deposit, located in the western part of the Bangonghu–Nujiang belt was recently recognized as a superlarge prospect. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was used to characterize the Duolong porphyry deposit alteration area, and three methods, color enhancement, band ratio transformation, and spectral angle mapping, were utilized to extract the phyllic and argillic alteration zones, which are typically considered the most important predictors of porphyry copper. Seven prospecting areas, which match mapped alteration zones, were delineated in the Duolong deposit. In addition, an ASTER image of the eastern region of the Bangonghu–Nujiang belt in the Xiongmei area was used to extract alteration information, and an area with image characteristics similar to the Duobuza and Bolong ore deposits was identified as a prospecting area. Numerous malachite outcrops were identified in the field, and both laboratory analysis and isotopic dating confirmed that the deposit had formed concurrently with the Duobuza deposit (119 Ma). Geologic mapping at the 1:5000 scale was conducted in the area, and three types of ore-bearing rocks were identified, indicating that this area has significant potential to host ore deposits. The discovery of the Xiongmei copper mining area is significant for the Bangonghu–Nujiang belt.