Study On Extraction Method Of Remote Sensing Alteration Information In Yulong Porphyry Copper Belt

The alteration and regional tectonic information related to the porphyry copper mine were extracted by remote sensing technology combined with the regional geological background information,on the basis of the remote sensing prospecting model and target selection project of the porphyry copper deposit of southern-middle part of Sanjiang in the southwest area.To investigate the extraction method of anomalous information extraction of multi-source remote sensing data and extraction of tectonic information,the Large-scale Yulong Porphyry Copper Mine was selected as the study area.The OLI data and ASTER data were selected in the study,and a variety of methods were used to extract the alteration information.At the same time,compared the 1/4 standard method with the traditional threshold method,when selecting the extraction threshold,the best extraction method for the alteration of the porphyry copper ore in the study area was proposed according to various alteration information.The main contents and achievements of this research are as follows:(1)On the basis of the topography and geology of the study area,the contrastive analysis of the remote sensing data in different periods were performed,from which the good was selected.The remote sensing data were subjected to radiation correction,band synthesis and other pretreatment.Through remote sensing image mosaic,fusion and image contrast enhancement and other processing,a remote sensing image was produced and the line ring structure information was extracted.(2)The alteration information was carried out by using the band ratio method,the principal component analysis method,the spectral angle matching method,the mixed pixel decomposition method and the logic operator algorithm,after masking the clutter in the remote sensing image.(3)The comparison of OLI data and ASTER data extraction alteration information was carried out,showing that anomalies of the two were basically the same in spatial distribution.However,ASTER data has a certain advantage in extracting hydroxyl,because of its better spectral resolution in shortwave infrared image,so that different types of hydroxyl-containing alteration of minerals can be recognized.(4)In this paper,the 1/4 standard deviation method was used to segment the threshold.The 1/4 standard deviation method and the traditional threshold method were compared and analyzed quantitatively.The precision of the threshold cutting is improved by the method of mutual evaluation,showing that the 1/4 standard deviation method can effectively extract the alteration information.(5)Combining the multi-source information such as the geological situation of the study area,the surrounding rock of the porphyry copper deposit,and linear-ring structure information,the alteration information was optimized by the use of the ASTER data in a qualitative-quantitative way,and the alteration extraction results were analyzed and superimposed.The superimposed analysis shows that the Yulong mining area has good mineralization and alteration zonation.