摘要:
在高光谱遥感找矿应用中,从影像上提取的蚀变信息经常包含了很多对找矿无用的信息。为了避免这些无用信息,本研究选取植被覆盖的云南普朗斑岩铜矿区作为研究区,使用该区高光谱遥感数据分别提取蚀变岩和蚀变矿物的信息,分析它们对找矿的有用性。提取蚀变矿物信息使用的是从影像上提取的矿物端元参考光谱,光谱匹配采用的是光谱角方法;提取蚀变岩信息使用的是野外蚀变岩参考光谱,光谱匹配不仅考虑光谱的整体形态,而且考虑吸收谷位置形态。在蚀变岩识别图上,4个典型蚀变岩点的野外验证表明:识别结果与实地地物基本一致。但是,在蚀变矿物信息图中,这4个圈定点无任何信息。这表明:这些点的蚀变岩信息较其表面蚀变矿物信息更丰富,因而能被有效提取出。通过比较蚀变岩、蚀变矿物的信息分布图,发现:一些粘土矿物(比如硬石膏和高岭石)的大量信息分布在沉积岩区,因而可能是假的蚀变信息。这表明:通过蚀变岩光谱获取的蚀变信息比通过蚀变矿物光谱获取的蚀变信息更可靠。在蚀变岩信息提取中,比较吸收谷位置识别前后的结果表明:考虑光谱整体和局部形态比仅考虑整体形态的识别结果具有更高的可靠性。
Abstract:
Hyperspectral remote sensing (RS) has been widely used in mineral exploration. However, the information of altered minerals extracted from the RS image often contains some information which is useless for ore prospecting. In order to eliminate the useless information, the authors selected a vegetation covered area from the Pulang porphyry copper deposit in Zhongdian County of Yunnan Province as the study area, extracted the information of altered minerals and altered rocks separately from the hyperspectral image of the study area, and analyzed the usefulness of the information for ore prospecting. The altered minerals in the image were identified using the reference spectra extracted from the image, and the method of SAM (spectral angle mapper) was used in the identification, whereas the altered rocks in the image were identified by spectral matching of the overall shape of the spectrum and the absorption-band position in the spectral shape, with the field spectra of altered rocks used as the reference spectra. The four marked targets of altered rocks in the figures of recognition results were demonstrated, and the result showed that the identification results of these targets were consistent with the field ground objects. However, there was almost no information in the marked targets of the altered mineral maps. This phenomenon can probably be attributed to the fact that the altered rocks include more information than altered minerals on their surface in the RS image. A comparison between the alteration zones obtained by the altered spectra with those obtained by the spectra of alteration minerals shows that much information of such clay alteration minerals as anhydrite and kaolinite appears in the area of sedimentary rock, and hence such information might be false information of altered minerals, which suggests that the alteration zones obtained by the spectra of altered rocks are more reliable than those obtained by the spectra of altered minerals. In the identification of altered rocks using the RS data, the recognition results obtained by considering the overall and partial shape of the spectra have higher reliability than the results obtained by only considering the overall shape.
下载: