基于ASTER影像的蚀变异常提取方法研究——以赞比亚谦比希铜矿床地区为例

Research on the Methods for Extraction of Alteration Information by Using ASTER Data:A Case Study of the Chambishi Copper Deposit in Zambia

基于赞比亚谦比希(Chambishi)铜矿带中的多种蚀变矿物及其在ASTER影像VNIR-SWIR谱带的特征光谱分析,采用相对波段吸收深度(Relative absorption-Band Depth,RBD)和波段比值的方法对蚀变信息进行增强处理。用波段比值ASTER 2/ASTER 1和ASTER 3的RBD增强黄铁矿和黄铜矿信息,用ASTER 8的RBD增强白云石、方解石和黑云母信息,用ASTER 6的RBD增强绢云母信息;对已有的Crosta主成分分析法进行改进,将信息增强后的比值和RBD数据应用于Crosta法则,对谦比希铜矿及其附近区域进行蚀变信息提取。经已知铜矿床(点)验证及地质资料分析证明,上述方法能够有效地提取蚀变信息并识别研究区内主要矿物,提取结果可靠,可为蚀变异常提取工作提供参考。

Based on several altered rocks in the Chambishi copper deposit and the spectral characteristics of the rocks existing in VNIR - SWIR bands of ASTER data, the authors adopted the methods of Relative absorption - Band Depth（RBD）and band ratio to enhance the mineral alteration information in this paper. The band ratio of ASTER 2/ASTER 1 and the RBD of ASTER 3 were used to enhance the Chalcopyrite and pyrite information, the RBD of ASTER 8 was used to enhance biotite and calcite information, and the RBD of ASTER 6 was used to enhance the sericite information. To improve the existing method of Crosta principal component analysis, the authors applied the combination of the enhanced band ratio and RBD to Crosta method with the purpose of extracting the alteration information of the copper deposit and neighborhood areas in Chambishi. As proved by known copper deposit locations and geological analysis, the methods mentioned above can effectively extract the alteration information and distinguish the main minerals in the study area. The results are reliable, thus supplying references to the extraction of alteration information.