内蒙古朱拉扎嘎金矿ETM^+数据提取蚀变异常方法研究

Study on Abnormal Extracting of Altered Rocks Using ETM^+ Data in Zhulazhaga Gold Deposit,Alashan Region,Inner Mongolia

中国西北部大部分地区属于荒漠景观区,自然条件恶劣,常规的地质、物探、化探找矿工作难度大,如何借助遥感技术进行矿产资源勘查,是地质工作者积极探索的方向之一。本次工作选择内蒙古阿拉善盟朱拉扎嘎金矿作为实验区,利用卫星遥感ETM+数据进行蚀变异常提取方法研究。从蚀变矿物的波谱特征出发,对Crosta法则进行改造,建立了适合本区的异常提取模型:铁化蚀变异常提取以Band2、Band3、Band4、Band5/Band1主成分分析为核心技术;含羟基和碳酸盐化蚀变异常提取以Band2、Band4、Band5、Band7主成分分析为核心技术。运用该模型完成了矿区及其外围蚀变异常提取工作,经过地面光谱验证,检测到铁化、含羟基和碳酸盐化蚀变矿物,认为提取方法合理,提取结果可信。本次研究工作可以为矿区外围找矿提供新方法,为推广和应用遥感技术在荒漠景观区找矿提供参考。

Most part of northwestern China belongs to arid/semi-arid. The natural conditions are very hard. Exploring mineral resources are very difficulty using traditional geology, geophysical and geochemical methods. Now it is very urgent for geologist to explore mineral resources using new technique such as remote sensing in this area. We chose Zhulazaga gold deposit as a testing district, and studied on abnormal data extracting of altered rocks using Enhanced Thematic Mapper plus （ETM^＋ ）images. The study began from the characteristics of minerals wave spectrum, and made some corrections to Crosta. The principal component analysis （PCA） method has been used on selected 4 bands. A new model of abnormal extracting on altered rocks using ETM ^＋ images created. Altera- tions with iron oxide have been enhanced by using Band 2, Band 3, Band 4, Band 5/Band 1 of ETM^＋ data; Band 2, Band 4, Band 5, and Band 7 will be key analysis data for abnormal extracting for argillic and carbonation alteration. Extracting abnormal data of altered rocks in the deposit and beyond areas show that there are iron, argillic and carbonation alteration. Geology and geochemical analysis showed a good correlation with hydrothermal alteration information extracted from ETM^＋. This study provides a new method for prospecting in the arid/semi-arid area by remote sensing techniques in the deposit and beyond areas. This paper made some contributions for oreprospecting in the arid/semi-arid area by remote sensing techniques.