基于ETM+的几内亚铝土矿蚀变信息提取方法研究

A Study on Extraction of Bauxite Alteration Information of Guinea based on ETM+ Remote Sensing Data

铝土矿上覆厚度为0.5～9m的铁矾土(铁帽)的特点使得研究区内铝土矿蚀变信息在一定程度上可以由铁帽信息来表示。在分析区内铝土矿的含矿体系、光谱特征和遥感影像特征的基础上,提出充分利用铝土矿与铁帽信息的相关性,通过提取铁帽信息来间接提取铝土矿蚀变信息。介绍了通过"多元数据分析+比值分析+主成分分析+分类"提取铝土矿蚀变信息的方法,结果表明:利用该方法提取的蚀变信息与已知矿体的吻合率为63%,蚀变信息提取准确度较主成分分析(44.6%)和比值分析(54.7%)有较大幅度提高。该方法能够抑制植被覆盖及第四系等干扰因素的影响,快速有效地提取几内亚金迪亚地区的铝土矿蚀变信息,初步查明区内铝土矿的分布规律,为进一步找矿勘查工作提供了有效的指示信息,这对于找矿勘查成本高的海外勘探区,具有重要的现实意义。

The overlying iron cap formed from Limonite with the thickness of 0.5~9 m of bauxite is an important characteristic of bauxite in study area,which makes the bauxite altered information can be represented by iron cap information in a certain degree.Based on the feature analyses of ore-contained system,spectral and remote sensing images,utilizes the correlation between iron cap information and bauxite altered information to extract bauxite altered information indirectly by extracting iron cap information is proposed.This paper presents a method of ＂multivariate data analysis ＋ ratio analysis ＋ principal component analysis ＋ classification＂ to extract bauxite altered information.Test results show that the coincidence rate with given ore bodies and bauxite altered information extracted by the presented method is 63%,while the extraction accuracy of principal component analysis and ratio analysis is 44.6% and 54.7% respectively.The extraction accuracy is much higher than that of principal component analysis and ratio analysis.The method proposed in this paper can extract bauxite altered information in Kindia,Guinea rapidly and effectively by inhibiting vegetation coverage and Quaternary effectually.With the help of the presented method,the distribution of bauxite in the study area is verified preliminarily,which provides effective instruction information for the further prospecting and exploration.It is of great realistic significance for overseas exploration area with high cost of ore exploration.