基于矿物光谱指数的蚀变信息提取——以西藏多龙铜金矿集区ASTER数据为例

Extraction of the Alteration Information Based on Mineral Spectrum Index:A Case Study of ASTER Data in the Duolong Copper-Gold Concentrate Area

矿物光谱指数是利用比值的方法增强Fe和含OH矿物在可见光、短波红外区间的吸收特征,进而提取蚀变矿物信息的一种方法。由于斑岩型矿床的蚀变分带特征明显,西藏多龙矿集区中集中了斑岩型、浅成低温热液型等铜、金矿床,通过矿物光谱指数的计算提取相关蚀变信息,对该区域的下一步找矿具有指导意义。本文采用矿物光谱指数(5+7)/6、(6+9)/8等方法提取了镁、铝两类羟基及铝羟基类下的高岭石等蚀变信息,采用5/4、2/1的方法提取了二价铁、三价铁的蚀变信息。经过与OLI影像采用PCA方法及野外实地勘查采样,证实了利用本文方法所提取的蚀变信息有效。

Mineral spectral index is a method to enhance the absorption characteristics of Fe and OH contained minerals in the visible and short wave infrared range by using the ratio method, and then to extract the alteration mineral information. As the alteration zoning of porphyry - type deposit has obvious characteristics, and in Tibet Duolong diggings it is a concentration area of porphyry, shallow epithermal copper and gold deposits, thus the extraction of alteration information by the calculation of mineral spectral index is significance for next - step prospecting in the region that next. In this paper, the alteration information of kaolinite, whose classify are hydroxyl groups of magnesium and aluminum, is extracted using the （5 ＋ 7）/6, （6 ＋ 9）/8 method, and the alteration information of bivalent iron and trivalent iron is extracted using the 5/4, 2/1 method. The effectiveness of the proposed method is verified by the PCA method and the field survey sampling in the field of OLI image.