基于ASTER的甘肃柳园地区蚀变信息提取与找矿预测

热液矿床常伴随一定的矿化蚀变类型,根据一定的矿化蚀变类型可以预测潜在的成矿有利区。甘肃柳园地区地处黑山—咸泉子深大断裂,热液型矿点多、蚀变丰富,且基岩出露好,可以作为提取遥感蚀变信息的良好示范区。使用ASTER遥感数据,利用主成分分析(principle component analysis,PCA)方法进行的铁染、羟基蚀变异常和碳酸盐化识别及基于SiO₂定量反演的硅化蚀变异常提取结果,与实际情况吻合度达88.9%。通过对区内已知矿床成矿作用、区域构造、蚀变信息和岩石分布特征的研究与分析,成功圈定2处成矿有利区,为该地区找矿勘查提供了依据。研究实例验证了基于ASTER数据的PCA蚀变信息提取和SiO₂定量反演的硅化蚀变异常提取方法的可靠性。该方法可推广至同等类型区域的遥感蚀变信息提取。

Extraction of alteration information and oreprospecting based on ASTER data in Liuyuan area of Gansu Province

Hydrothermal deposits are often accompanied by a certain type of mineralized alteration, which can indicate potential favorable metallogenic areas. The Heishan-Xianquanzi deep fault at Liuyuan area in Gansu Province can be regarded as one of the best demonstration areas for alteration information extraction based on remote sensing data because of its numerous types of hydrothermal deposits, abundant alteration, and well exposed bedrocks. In this paper, with the ASTER images, principal component analysis(PCA) was used to extract the anomalous information of iron-stain, hydroxyl alteration and carbonate, and the quantitative inversion of SiO₂ content of surface rock was used to extract silicified alteration. Comparing with the existing geological data, the field verification shows that the extracted information is in good agreement with the actual situation,and the relevant factor reaches 88.9%. Based on the known mineralization in the mining area, regional structure, remote sensing alteration information and rock distribution, two favorable prospecting areas were successfully delineated, which provides great support for exploration in this area. This study proves the reliability of the alteration anomaly extraction by the method of PCA and the quantitative inversion of SiO₂ content based on ASTER data, which can be extended to the alteration information extraction of similar areas.