Abstract:

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.

Key words: Sangmugang in Tibet, ETM+ remote sensing, linear structure interpretation, extraction of alteration information, metallogenic prognosis