The Study And Application Of Extracting Mineralized Alteration Remote Sensing Anomaly In Beishan Area Of Inner Mongolia

Remote Sensing technology appeared in 1960's as a new potential technology, and it was applied on military firstly. Since it appeared, the big amount of data and how to extract desirable information efficiently and correctly are the objectives of Remote Sensing researchers to get. They are trying ceaseless to look for the better solution. We have a new method of discovery ore since the Lansat-4 has the two short infrarede Waves: TM5(1.55-1.75μm) andTM7 (2.08-2.35μm).We can use it to extact the useful hydrothermal alteration information.The alteration of country rock is a very normal and regular phenomenon occurs during ore forming, it's very important information of mineralization, and the alteration of country rock most possibly predicts the ore discovery. Meanwhile, we can estimate the ore type and concentration degree based on the alteration area and intension. The traditional exploration methods always need ground survey to define alteration zone which cost lots of man power and financial support. Through extracting mineralized alteration from digital images, we can reduce much target area, focus on the possible mineralized zone, and save a big amount of man power and material cost. Especially in the area which has bad weather, little plant cover and low work degree, Remote Sensing alteration extracting has a virtue beyond comparison. Beishan locates in the Gobi of northwest China, which crosses Inner Mongolia, Gansu and Xinjiang. It is 500 km long from west to east and 240 km wide from south to north, which area is about 120,000 km2. The crisscross structures and faults and active magma activities make the zone become one of the most important ore forming zones of nonferrous and precious metal.This article based on the Remote Sensing Survey in Beishan of Inner Mongolia, selected the final alteration anomaly extracting model through analyzing the relations between country rock alteration and all kinds of mineralization. Then extract anomaly spots, combine with known occurrences, tectonic, field sampling and geochemistry to check the validity to, and define the exploration target area. After many experiments and comparisons, we found that every method has its virtue and shortage, and we can not get ideal result by using one method. So we combine the several methods to extract anomaly and consider couples of alteration extracting results to confirm possible target area.According to the ore forming rules and compared with mineralization symbols, we defined three categories targeting areas: include 4 targeting areas of category I, 12 targeting areas of category II and 26 targeting areas of category III.