基岩裸露区蚀变岩遥感信息的提取方法

THE METHOD OF AbstractING REMOTE SENSINGINFORMATION OF ALTERATED ROCKS INTHE UNCOVERED BEDROCKS AREA

笔者利用与金属矿化相关的蚀变岩的ＴＭ多波段图像像元亮度值曲线的双峰特性（ＴＭ３和ＴＭ５为高值），以柳沟峡地区为样区，进行了提取蚀变岩遥感信息的方法研究，改进了Ｃｒｏｓｔａ信息提取方法，认为用ＴＭ１＋ＴＭ２、ＴＭ４／ＴＭ３、ＴＭ５、ＴＭ７组合进行主分量分析所获得的蚀变岩遥感异常图效果最佳。将该方法用于北祁连山西段，疏勒河以东９０００ｋｍ２区域内蚀变岩遥感信息提取，其结果是：在１０３处已知矿产地中的８６处有蚀变岩遥感异常信息显示，符合率达８３．５％，进而预测了找矿靶区１１５处。

he in-situ sampling and the on-image sampling have confirmed that in Liugouxia area the altered rocks, being closely related to metallic mineralization, are characterized by the double peaks on the reflective spectra curves (high reflection in TM3 and TM5 bands). This provides the prerequisite for abstracting the information of the alteration rocks from the remote sensing image. This paper, by studying the method of abstracting the alterated rocks information, demostrates that the method of PCA (using TM1+TM2, TM4/TM3, TM5,TM7) is the best for the information abstraction. This method can be called modified Crosta method. Among the 103 deposits located in the 9 000 square kilometers area, there are 86 deposits that have the corresponding alteration anomalies on the anomaly image is obtained by the modified Crosta method. The coincidence coefficient is as high as 83.5%. Another 115 new targets were predicted according to this anomaly image and rock types as well as structrural conditions.