Research On The Exploration Model Of Remote Sensing In Porphyry Copper Belt,Tibet

There are several metallogenic belts in Tibet Autonomous Region, such as Pangong Lake-Nujiang River metallogenic belt, Gangdise metallogenic belt, and Sanjiang metallogenic belt, where enrichment of mineral products include copper, iron, lead and zinc, gold, silver chromite, nickel, etc. But with the reasons that high altitudes, serious of topographic relief and weak of geological basis, geophysical and geochemical exploration data is badly limited, of which the scale is small except minority areas there. Recent years, because of the advantages of remote sensing technology, such as abundant information, rapid speed of acquiring the data and short of the cycle, few restriction coming from surface condition, and so on, which get great application in plateau regions, such as Tibet plateau. There are several excellent research achievements about remote sensing technology used in intensive study of typical ore deposits combined with the background of geological research and geophysical-geochemical technique. Three large porphyry copper deposits, named as Duolong, Qulong, and Yulong, were selected to carry out remote sensing geological studies and design the remote sensing prospecting mode in this study. Based on the analysis of the geological background of the study area, the features of remote sensing image are analyzed, remote sensing interpreting marks are established, and information in linear structure, circular structure, color anomalies and acidic rock related to mineralization are interpreted, with analyzing geological remote sensing characteristics followed. Combination of linear structure and trend of the central line construction has great significance for the deposit. And fracture intersection and confining parts and wire ring intersection parts are important.Based on the spectral characteristics analysis of the typical alteration minerals, ratio method and principal component analysis are used to extract all kinds of the alteration information of ETM+ and ASTER. And then, response of each result are analyzed and compared. Whether or not responding alteration information, distribution characteristics of the ore belt, especially the deposit and its periphery, are basically identical. The final purpose of extracting of the alteration information of remote sensing is to study the relationship between alteration information and deposit. After that, guidance on remote sensing of ore-prospecting clues is provided. Indication for mineral deposits from the spatial distribution characteristics of alteration information is more important than the intensity and amount of alteration informationGenerally, alteration information is extracted from the spectrum measured in laboratory or outside. Because of the influence coming from the sensors, atmospheric transport, surrounding surface features, topography and other factors, remote sensing data always get disturbed. Image spectrum can reflect the spectral characteristics of mixed pixel, and reflex the information of a certain type of geological body with common characteristics. Combined with the known ore body planar projection, image spectrum of geological body and surrounding rock in the three study areas are extracted. In addition, in order to provide more information on remote sensing prospecting, spectral feature fitting method is used to extract the information of the geological body.In a word, prospecting model in every area is established through analyzing the favorable geological conditions and interpreting remote sensing geological features and extracting remote sensing alteration information and information of geological body. And characteristic analysis method is adopted to establish the function of metallogenic favorable degree of study area. Based on the result of above work, metallogenic favorable degree is analyzed and prospecting targets are delineated efficiently. Thereby, prospecting model of porphyry copper mine in Tibet is established, and the remote sensing prospecting model are generalized to the prospecting applications of porphyry copper ore in Tibet.