ASTER数据在遥感蚀变填图中的应用研究——以内蒙古花敖包特银铅锌多金属矿床为例

Application of ASTER remote sensing data to hydrothermal alteration mapping and prospecting prediction:A case study of Huaaobaote Pb-Zn-Ag polymetallic deposit in Inner Mongolia

花敖包特是位于内蒙古西乌珠穆沁旗的一个大型脉状银铅锌多金属矿床,其矿区的蚀变矿物主要是黏土矿物、绿泥石和方解石,此外还可见孔雀石、萤石和赤铁矿等局部蚀变矿化。结合花敖包特矿床的地质特征,本研究利用高级星载热辐射和反射探测器(ASTER)获取的遥感数据进行蚀变矿物填图。利用ASTER可见光-近红外波段和短波红外波段,对校正后遥感数据采用波段比值分析、波段组合分析和主成分分析来提取黏土矿物、绿泥石和方解石化蚀变。利用ASTER热红外波段,根据相关数值关系,对校正后遥感数据计算二氧化硅含量、QI值以及CI值来分析地质体二氧化硅含量变化规律和碳酸盐化蚀变。结合野外勘查结果发现,主成分分析、波段组合分析能够初步划分矿区绿泥石化、碳酸盐化和黏土化蚀变带以及硅化带,其中主成分分析方法取得的效果较好,显示矿区北部以绿泥石化带为主,南部以碳酸盐化和黏土化混合带为主,而热红外波段数值分析方法在矿田尺度下对矿区附近的硅化带和碳酸盐化蚀变也具有一定的识别能力。

Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)data are widely accepted as a preferred data source for altered minerals mapping in combination with the field sampling spectral curves.In the mining area of the Huaaobaote Pb-Zn-Ag polymetallic deposit,Inner Mongolia,the altered minerals mainly include clay,calcite and chlorite.In this study,the authors used visible near infrared(VNIR)and shortwave infrared(SWIR)bands to obtain the information about these alteration types.Relative absorption-band depth method,simple band combination method and principal component analysis were conducted in the analysis.Thermal infrared(TIR)bands were also used to get the information about silicification and carbonatization by numerical relation.After synthesizing these results combined with field investigation,the most critical information can be effectively discriminated.In particular,the results from principal component analyses are relatively useful in indicating the alteration zonation,whereas the TIR bands show good potential in detecting surface silicification and carbonatization.