Mineral mapping in the Duolong porphyry and epithermal ore district, Tibet, using the Gaofen-5 satellite hyperspectral remote sensing data

Abstract

Remote sensing technology is an exploration method that can directly map distribution of alteration minerals or zones associated with different types of mineral systems. Hyperspectral remote sensing can identify key pathfinder minerals and compositional variations within minerals. The Duolong porphyry-epithermal ore district, which has proven reserves of approximately 20 million tons of Cu and 420 tons of Au, is part of an emerging world-class metallogenic area in the western part of the Bangong Co-Nujiang metallogenic belt, Tibet, China. The Gaofen-5 hyperspectral (GF-HS) reflectance data were used to map the distribution patterns of hydrothermal alteration and to locate areas potentially containing mineral deposits in the Duolong ore district (DOD). Based on the mixture tuned matched filtering (MTMF) technique and the absorption feature wavelength positions of the minerals, an alteration map was generated using GF-HS data for mineral mapping in the DOD with sparse vegetation. The widely distributed advanced argillic alteration (alunite + pyrophyllite + kaolinite ± dickite), phyllic alteration (high content of Al-rich white mica), propylitic alteration (Mg-rich chlorite), and limited argillic alteration (kaolinite ± dickite ± white mica) were mapped in detail. The distribution patterns of alteration in known deposits were fairly consistent with the mineralogical information obtained in previous studies. In addition, we identified potential mineralization areas with characteristics similar to the Duobuza, Bolong and Naruo porphyry deposits.