Alteration is regarded as significant information for mineral exploration. In this study, ETM＋ remote sensing data are used for recognizing and extracting alteration zones in northwestern Yunnan （云南）, China. The ...Alteration is regarded as significant information for mineral exploration. In this study, ETM＋ remote sensing data are used for recognizing and extracting alteration zones in northwestern Yunnan （云南）, China. The principal component analysis （PCA） of ETM＋ bands 1, 4, 5, and 7 was employed for OH alteration extractions. The PCA of ETM＋ bands 1, 3, 4, and 5 was used for extracting Fe^2＋ （Fe^3＋） alterations. Interfering factors, such as vegetation, snow, and shadows, were masked. Alteration components were defined in the principal components （PCs） by the contributions of their diagnostic spectral bands. The zones of alteration identified from remote sensing were analyzed in detail along with geological surveys and field verification. The results show that the OH^- alteration is a main indicator of K-feldspar, phyllic, and prophilized alterations. These alterations are closely related to porphyry copper deposits. The Fe^2＋ （Fe^3＋） alteration indicates pyritization, which is mainly related to hydrothermal or skarn type polymetallic deposits.展开更多
Satellite remote sensing data are usually used to analyze the spatial distribution pattern of geological structures and generally serve as a significant means for the identification of alteration zones. Based on the L...Satellite remote sensing data are usually used to analyze the spatial distribution pattern of geological structures and generally serve as a significant means for the identification of alteration zones. Based on the Landsat Enhanced Thematic Mapper （ETM＋） data, which have better spectral resolution （8 bands） and spatial resolution （15 m in PAN band）, the synthesis processing techniques were presented to fulfill alteration information extraction： data preparation, vegetation indices and band ratios, and expert classifier-based classification. These techniques have been implemented in the MapGIS-RSP software （version 1.0）, developed by the Wuhan Zondy Cyber Technology Co., Ltd, China. In the study area application of extracting alteration information in the Zhaoyuan （招远） gold mines, Shandong （山东） Province, China, several hydorthermally altered zones （included two new sites） were found after satellite imagery interpretation coupled with field surveys. It is concluded that these synthesis processing techniques are useful approaches and are applicable to a wide range of gold-mineralized alteration information extraction.展开更多
The HySpex hyperspectral data used in this study have a wide spectral response range,narrow bandwidth,and high spatial resolution,and they can be effectively applied to the extraction of mineral alteration information...The HySpex hyperspectral data used in this study have a wide spectral response range,narrow bandwidth,and high spatial resolution,and they can be effectively applied to the extraction of mineral alteration information.We explore how to extract effective information from remote sensing images through remote sensing image classification technology and explore its utilization in geological science.This study aims to verify the reliability and accuracy of alteration information extracted by using a super-low altitude detection platform equipped with powered delta wings mounted with HySpex hyperspectral sensors in the Yudai area of the Kalatage district.Field data were collected and analyzed using Analytical Spectral Devices(ASD),and the results were compared with those obtained from the United States Geological Survey(USGS)spectral library.The analysis of the geological background and HySpex hyperspectral data was enhanced by Minimum Noise Fraction(MNF)transformation coupled with the Pixel Purity Index(PPI)to extract endmembers of altered minerals,including chlorite and jarosite,from different spectra(SWIR and VNIR)and spectral wavelengths.Additionally,two classification methods,the Spectral Angle Mapper(SAM)and Support Vector Machine(SVM),were applied to the data for effective mineral mapping.The best-performing method,i.e.,SVM,was validated using ground-truth information obtained during field observations.The results from the classification methods revealed accuracies of 59.57%for SAM and 69.25%for SVM.The HySpex hyperspectral data obtained using a super-low altitude detection platform proved highly effective for detecting altered rock information.Thus,this approach has great potential for the rapid identification of geological and mineralogical features,especially in complex terrains.展开更多
基金supported by the project "Remote Sensing Alteration Abnormity Extraction from Geological Survey in Northwestern Yunnan, China" from China Geological Survey
文摘Alteration is regarded as significant information for mineral exploration. In this study, ETM＋ remote sensing data are used for recognizing and extracting alteration zones in northwestern Yunnan （云南）, China. The principal component analysis （PCA） of ETM＋ bands 1, 4, 5, and 7 was employed for OH alteration extractions. The PCA of ETM＋ bands 1, 3, 4, and 5 was used for extracting Fe^2＋ （Fe^3＋） alterations. Interfering factors, such as vegetation, snow, and shadows, were masked. Alteration components were defined in the principal components （PCs） by the contributions of their diagnostic spectral bands. The zones of alteration identified from remote sensing were analyzed in detail along with geological surveys and field verification. The results show that the OH^- alteration is a main indicator of K-feldspar, phyllic, and prophilized alterations. These alterations are closely related to porphyry copper deposits. The Fe^2＋ （Fe^3＋） alteration indicates pyritization, which is mainly related to hydrothermal or skarn type polymetallic deposits.
基金The paper is supported by the Research Foundation for Out-standing Young Teachers, China University of Geosciences (Wuhan) (Nos. CUGQNL0628, CUGQNL0640)the National High-Tech Research and Development Program (863 Program) (No. 2001AA135170)the Postdoctoral Foundation of the Shandong Zhaojin Group Co. (No. 20050262120)
文摘Satellite remote sensing data are usually used to analyze the spatial distribution pattern of geological structures and generally serve as a significant means for the identification of alteration zones. Based on the Landsat Enhanced Thematic Mapper （ETM＋） data, which have better spectral resolution （8 bands） and spatial resolution （15 m in PAN band）, the synthesis processing techniques were presented to fulfill alteration information extraction： data preparation, vegetation indices and band ratios, and expert classifier-based classification. These techniques have been implemented in the MapGIS-RSP software （version 1.0）, developed by the Wuhan Zondy Cyber Technology Co., Ltd, China. In the study area application of extracting alteration information in the Zhaoyuan （招远） gold mines, Shandong （山东） Province, China, several hydorthermally altered zones （included two new sites） were found after satellite imagery interpretation coupled with field surveys. It is concluded that these synthesis processing techniques are useful approaches and are applicable to a wide range of gold-mineralized alteration information extraction.
基金supported by National Key R&D Program of China(GrantNo.2018YFC0604001-3)B&R Team of Chinese Academy of Sciences(GrantNo 2017-XBZGBR-002)+2 种基金Key Project of Natural Science Foundation of China-Xinjiang Joint Fund(No U1803241)National Nature Science Foundation(GrantNo U1803117 and U1503291)UCAS Scholarship for International Students,Xinjiang Institute of Ecology and Geography,CAS.
文摘The HySpex hyperspectral data used in this study have a wide spectral response range,narrow bandwidth,and high spatial resolution,and they can be effectively applied to the extraction of mineral alteration information.We explore how to extract effective information from remote sensing images through remote sensing image classification technology and explore its utilization in geological science.This study aims to verify the reliability and accuracy of alteration information extracted by using a super-low altitude detection platform equipped with powered delta wings mounted with HySpex hyperspectral sensors in the Yudai area of the Kalatage district.Field data were collected and analyzed using Analytical Spectral Devices(ASD),and the results were compared with those obtained from the United States Geological Survey(USGS)spectral library.The analysis of the geological background and HySpex hyperspectral data was enhanced by Minimum Noise Fraction(MNF)transformation coupled with the Pixel Purity Index(PPI)to extract endmembers of altered minerals,including chlorite and jarosite,from different spectra(SWIR and VNIR)and spectral wavelengths.Additionally,two classification methods,the Spectral Angle Mapper(SAM)and Support Vector Machine(SVM),were applied to the data for effective mineral mapping.The best-performing method,i.e.,SVM,was validated using ground-truth information obtained during field observations.The results from the classification methods revealed accuracies of 59.57%for SAM and 69.25%for SVM.The HySpex hyperspectral data obtained using a super-low altitude detection platform proved highly effective for detecting altered rock information.Thus,this approach has great potential for the rapid identification of geological and mineralogical features,especially in complex terrains.
