ASTER数据在遥感蚀变填图中的应用研究——-以内蒙古半拉山钼矿床为例

使用ASTER数据对内蒙古半拉山隐爆角砾岩型钼矿床进行矿床尺度的蚀变填图。 使用VNIR和SWIR谱段的单波段RBD分析、简单波段组合分析提取岩性分带信息, 使用PCA主成分分析, 提取黏土化、青磐岩化、碳酸盐化和褐铁矿化的蚀变信息, 使用TIR谱段提取硅化、钾化和碳酸盐化的蚀变信息, 获得半拉山矿床自西向东分布青磐岩化带、碳酸盐化带和黏土化带的蚀变带分布图。结合实地勘测结果, 证实ASTER数据对斑岩型矿床及相关的隐爆角砾岩型矿床蚀变带的识别具有较好效果。在矿床尺度上可以应用VNIR数据和SWIR数据有效区分黏土化、青磐岩化和碳酸盐化, 在矿田尺度上可以应用TIR数据区分硅化和钾化, 但对于只在VNIR谱段具有光谱特征的铁氧化物, 蚀变解译效果较差。

Application of ASTER Data in Hydrothermal Alteration Mapping and Prospecting Prediction: Take an Example of Banlashan Molybdenum Deposit, Inner Mongolia

An advanced spaceborne thermal emission and reflection radiometer (ASTER) data were evaluated for the hydrothermal alteration mapping of the Banlashan cryptoexplosive breccia type molybdenum deposit, Inner Mongolia. Relative absorption-band depth (RBD) and simple band combination method in visible near infrared (VNIR) and shortwave infrared (SWIR) bands were used to fetch the information about lithological distribution. Principal component analyses (PCA) were applied to get alteration information of clay, chlorite, carbonate and limonite. Thermal infrared (TIR) bands were used to get information of silicification and potassic alteration. An eastward propylitization, carbonate and argillic alteration zone was defined in the Banlashan deposit. Combined with field research, ASTER data are good at characterizing the alteration area of both porphyry deposits and breccia-type deposits. With VNIR and SWIR bands, argillic, propylitic and carbonic alterations in a single deposit can be effectively discriminated, and TIR bands can be used to detect surface silica and potassic alterations on a larger scale. It is less effective to detect Fe-oxide alteration, which only has identified characteristics in the VNIR bands.