Abstract:

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. Alterations 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 ore-prospecting in the arid/semi-arid area by remote sensing techniques.

Key words: altered minerals, ETM⁺, principal component analysis (PCA), Zhulazhaga gold deposit, Inner Mongolia