基于红外光谱技术研究内蒙古乌奴格吐山斑岩铜钼矿蚀变和矿化特征

A Study on Alteration Mineral Assemblages and Mineralization Characteristics of a Wunugetushan Porphyry Copper-Molybdenum Deposit in Inner Mongolia,China,Based on Infrared Spectroscopy

近年来,红外光谱技术在矿物学研究、地质勘探与找矿等方面发挥了重要作用。本文通过测量与分析内蒙古乌奴格吐山斑岩铜钼矿Z661钻孔岩心短波红外和热红外波段的光谱,快速厘定了该矿床的蚀变矿物类型及组合特征。结果表明:乌奴格吐山斑岩铜钼矿床蚀变矿物主要有石英、钾长石、绢云母、伊利石、高岭石和蒙脱石等。蚀变矿物组合在空间上呈现出明显的分带性,其中石英+伊利石+绢云母+钾长石与矿化关系最为密切,可作为找矿的标型矿物组合;结合钻孔Cu、Mo矿化分布特征,发现绢(白云母)2200nm处吸收峰位置的波长偏移与成矿中心距离有关,波长变小,更趋向于成矿中心;且伊利石结晶度(IC)越大,结晶度较高,矿化程度强。因而,该技术方法通过蚀变矿物波谱,能够快速圈定斑岩铜钼矿蚀变矿物组合,进而提高勘查效率。

BACKGROUND:In recent years,infrared spectroscopy and thermal infrared spectroscopy have played an important role in mineralogy research,geological exploration and prospecting.OBJECTIVES:To investigate alteration minerals and mineralization features of a Wunugetushan porphyry copper-molybdenum deposit in Inner Mongolia.METHODS:Core samples were scanned by infrared spectroscopy core scanning system and analyzed by TSG 8.0.RESULTS:The alteration minerals of the Wunugetushan porphyry copper molybdenum deposit mainly included quartz,potassium feldspar,sericite,illite,kaolinite and montmorillonite.The alteration mineral assemblage showed obvious zonation in space.Quartz+illite+sericite+potassium feldspar had the closest relationship with mineralization and can be used as the standard mineral assemblage for ore prospecting.By comparing with the spatial distribution of Cu and Mo mineralization,the wavelength shift of the absorption peak at 2200nm to shorter wavelengths was closely related to the mineralization center,and the IC value of illite reflects the degree of crystallization and mineralization.CONCLUSIONS:This technical method can be used to quickly delineate the alteration mineral assemblage of porphyry copper-molybdenum ore through the alteration mineral spectrum,thereby improving the exploration efficiency.