Application Of Short Wave Infrared(SWIR) Technique In Exploration Of Zhunuo In Tibet

Short-wave infrared(SWIR)technology is a new method of mineral exploration and research in recent years.The technology provides characteristic spectral bands based on the absorption of light energy by different particles of altered minerals,such as hydroxyl(OH-),carbonate(CO32-),sulfate(SO42-)and water molecules,so as to determine the type and content of target minerals.Because of its fast,low cost and high sensitivity,this technology is widely used in altered mineral mapping to guide mineral exploration.The application of short-wave infrared spectroscopy in the Gangdese metallogenic belt has begun.The Qulong porphyry copper deposit,Jiama copper polymetallic deposit,Niancun mining area in eastern Gangdese and Nuri large-scale copper polymetallic deposit in Tibet have all made good progress in SWIR exploration.Zhunuo copper deposit,located in the western part of the middle Gangdese metallogenic belt,is a large porphyry copper deposit discovered in recent years in China.Short-wave infrared spectroscopy has not been carried out in Zhunuo copper porphyry deposit before.In order to further elucidate the alteration and mineralization structure of Zhunuo porphyry copper deposit and effectively guide the next exploration work,six holes in two typical sections of Zhunuo porphyry deposit have been systematically tested and analyzed by short-wave infrared spectroscopy,and the identification of altered minerals and spectral parameters of altered minerals have been studied.Research on the spatial distribution of ore bodies.Four types of altered minerals have been identified: kaolinite,muscovite,chlorite and carbonate.Among them,muscovite minerals are mainly developed.Specific mineral types include: kaolinite,ordinary muscovite,polysilicate muscovite,montmorillonite,chlorite,Fe-chlorite,Mg-chlorite,Mg-Fe-chlorite,phlogopite,epidote,ankerite,siderite,illite and other 18 minerals.According to altered mineral assemblages,Zhunuo porphyry deposit can be divided into four zones: muscovite,muscovite+chlorite±epidote,muscovite+Illite,muscovite+illite+chlorite±epi dote.The extraction of spectral parameters of muscovite minerals and chlorite shows that the absorption intensity of Al-OH of muscovite increases(> 0.15),the peak position of Al-OH drifts towards short wave direction(< 2204 nm),the crystallinity of illite increases(> 1.25),and the opposite is far away from the ore body.Therefore,using these rules can effectively restrict the location of orebodies in Zhunuo porphyry deposit and provide a new direction for the exploration of porphyry copper deposits in Gangdese belt.