Mineral Alteration Extraction Using Remote Sensing In High Coverage Vegetation Area, South Zhuguang Granitic Batholith

South Zhuguang granite pluton area is one of the most important granite type uranium ore field regions in China. Using SPOT5 high resolution image and Landsat8 OLI muti-spectral data as data source, this article do some research on remote sensing geology, contains fault structures interpreting and mineral alteration extraction in high coverage vegetation area, and using aeroradiometric survey data to explore regions favorable for uranium mineralization and make suggestions for uranium mineral exploration. Mainly contains:(1)Setting up interpretation symbol for fault structures, then interpret and recognize more than 800 fault structures by using SPOT5 and Landsat8 OLI images. Moreover, Field confirmation on part of these interpreted faults showed a good result.(2) Mineral alteration anomaly like hematitization, chloritization and hydromica related to uranium mineralization are widely distributed in south of Zhuguang granite type uranium ore field, but the vegetation coverage is high in this area. Mineral alteration anomaly extraction by using remote sensing can be disturbed by vegetation and other factors. For remove or minimize interfere factors, the high value of band ratio Landsat8 OLI 5/4 image is used to mask vegetation, and the low value of band ratio 7/2 image to mask water and shadow, and quaternary vector layer to mask quaternary area. And based on decomposition of mixed pixels technology, the interference factors have been weakening, and the spectra of pixels rebuild. After those disturbance factors eliminated, the PCA(principal component analysis) method is applied to extract ferric anomaly and hydroxylate anomaly. With filtered and density separated, these two principle components distribution information of ferric anomaly and hydroxylate anomaly have acquired successfully in south Zhuguang granite pluton area and the extracting results are proved by field work.(3) Utilizing ArcMap software to tailor aero-radiometric data of Shpfile format in study area. As difference geochemistry mobility between uranium and thorium, activated uranium abundance, paleo-uranium abundance and uranium ore-forming favorability is apply to mineralization prediction, and these parameters are computed in each measure line, and then use IDW method to spatial interpolation. After the interpreted faults and ore fields added, this research suggested that muti-class contour line with faults intersections is favorable position for uranium ore formation.