内蒙古苏莫查干敖包萤石矿区遥感蚀变信息提取及其找矿指示意义

Extraction of remote sensing alteration information and its ore prospecting indication in Sumochagan Obao fluorite mining area,Inner Mongolia

利用遥感技术可以经济、有效地获取地质找矿信息。基于多光谱遥感数据的蚀变信息提取已在地质填图和找矿工作中广泛应用,近几年,中国高分五号(GF-5)高光谱数据以其较高的光谱分辨率为地表蚀变矿物的精细化识别提供了基础数据。文章结合Landsat-8 OLI多光谱和GF-5高光谱数据,对内蒙古苏莫查干敖包萤石矿及周边开展蚀变信息提取,分析有利成矿区域,并进行野外验证,进一步发掘外围矿产资源潜力并探究遥感地质勘查的可信度。笔者基于Landsat-8多光谱数据,利用主成分分析方法提取了铁染、羟基类蚀变,并对其异常等级进行了划分;基于GF-5高光谱数据运用最小噪声分离(MNF)算法、纯净像元指数(PPI)算法、混合调制匹配滤波(MTMF)填图方法,在研究区内提取出白云母、绿泥石、高岭石、磁赤铁矿和褐铁矿5种矿物。将两者蚀变信息提取结果叠加,笔者发现苏莫查干敖包萤石矿区及外围存在热液蚀变特征,具备金属成矿潜力,野外验证发现研究区除萤石外,还伴生有铅锌多金属矿。因此,笔者认为多光谱和高光谱遥感数据结合的蚀变信息提取在地质矿产资源勘查领域具有一定应用潜力。

Remote sensing technology can be used to obtain geological prospecting information economically and effectively.Alteration information extraction based on multispectral remote sensing data has been widely used in geological mapping and prospecting.In recent years,the high spectral resolution of GF-5 hyperspectral data from China has provided basic data for the identification of surface altered minerals.In this paper,based on Landsat-8 OLI multispectral data and GF-5 hyperspectral data,the alteration information of the Sumochagan Obao fluorite mining area and its surrounding area in Inner Mongolia were extracted and analyzed.Through field verification,the potential of peripheral mineral resources and the credibility of remote sensing geological exploration is explored.Based on Landsat-8 multispectral data,we used principal component analysis(PCA)to extract iron staining and hydroxyl alteration,then classified their anomaly levels.Based on the GF-5 hyperspectral data,the minimum noise separation(MNF)algorithm,the pure pixel index(PPI)algorithm and the mixed modulation matched filter(MTMF)mapping method are used to extract five minerals in the study area.They are muscovite,chlorite,kaolinite,maghemite,and limonite.The superimposed analysis of the extracted alteration information shows that the Sumochagan Obao fluorite mining area has the characteristics of hydrothermal alteration and has the potential for metal mineralization.Field actual verification shows that lead-zinc polymetallic ore is associated with the fluorite deposit.Therefore,the authors believe that alteration information extraction combined with multispectral and hyperspectral remote sensing data has certain application potential in the field of geological and mineral resources exploration.