西藏桑木岗地区遥感线性构造和蚀变信息提取与找矿预测

摘要

Based on remote sensing images and ore-prospecting prognosis,this article describes a way to extract linear structures and the alteration information through a case study from Sangmugang in Tibet.Using principal component analysis in ENVI4.8 software,convolution filter and morphological analysis and false color composite method,this article enhanced the linear structure and carried out a visual interpretation.The principal component analysis was used to effectively enhance the spectrum and space information in this area and to extract the iron-stained and hydroxyl-alteration information,according to the unique characteristics of alteration minerals.After compared the linear structure with iron-stained and hydroxy alteration information,it is found that the densely linear-structure areas are roughly coincident with the alteration anomaly information in a distribution trend of NW direction and are also consistent with the regional and metallogenic structural patterns;as a matter of fact,eight percent of known deposits are located in alteration anomaly areas.By the comprehensive analysis of linear structures,alteration information,regional geology,geochemical and geophysical information,stratigraphy,igneous rocks,etc.,ten exploration targets with three levels of probabilities are figured out,and the No.1 prospecting area is considered to be one of the most promising area.This study confirms that the linear structure in remote sensing images and the alteration information can be used as markers for ore-prospecting prognosis.%利用西藏桑木岗地区ETM+遥感数据,通过主成分分析、卷积滤波和形态学分析、假彩色合成等方法对线性构造做了增强处理,并进行目视解译.根据蚀变矿物特有的光谱特征,通过彩色合成、直方图拉伸进行信息增强处理,运用主成分分析方法对研究区铁染、羟基蚀变信息进行提取.比较线性构造和铁染、羟基蚀变信息可知,线性构造密集区与铁染、羟基蚀变异常区基本吻合,均呈近EW向展布,与区域构造、成矿构造格局一致,区内80％以上的已知矿点分布于铁染、羟基蚀变异常区.综合分析线性构造、遥感蚀变异常、区域地质、地球化学、已知矿床(点)等地学信息,圈定了3级7个成矿远景区,其中一级远景区是最有前景的异常区.