Temperature and emissivity separation and mineral mapping based on airborne TASI hyperspectral thermal infrared data |
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| Institution: | 1. Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085 China;2. China University of Geosciences (Beijing), Beijing 100083, China;3. China Aero Geophysical Survey and Remote Sensing Center for Land and Resources, Beijing 100083, China;4. Beijing Research Institute of Uranium Geology, Beijing 100029, China;1. 1-26 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, T6G2E3, Canada;2. German Remote Sensing Data Center, DLR, Munchnerstr. 20, D-82234, Germany, Germany;1. Tasmanian Eye Institute, Launceston, Tasmania, Australia;2. Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia;1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China;2. School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;1. Department of Earth and Atmospheric Sciences, University of Alberta, 1-26 Earth Sciences Building, Edmonton, Alberta, Canada T6G 2E3;2. CSIRO Earth Science and Resource Engineering, 26 Dick Perry Avenue, 6151 Kensington, Western Australia, Australia;3. DLR German Aerospace Centre, German Remote Sensing Data Centre, Münchnerstr. 20, D-82234 Wessling, Germany |
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| Abstract: | Thermal infrared remote sensing (8–12 μm) (TIR) has great potential for geologic remote sensing studies. TIR has been successfully used for terrestrial and planetary geologic studies to map surface materials. However, the complexity of the physics and the lack of hyperspectral data make the studies under-investigated. A new generation of commercial hyperspectral infrared sensors, known as Thermal Airborne Spectrographic Imager (TASI), was used for image analysis and mineral mapping in this study. In this paper, a combined method integrating normalized emissivity method (NEM), ratio algorithm (RATIO) and maximum–minimum apparent emissivity difference (MMD), being applied in multispectral data, has been modified and used to determine whether this method is suitable for retrieving emissivity from TASI hyperspectral data. MODTRAN 4 has been used for the atmospheric correction. The retrieved emissivity spectra matched well with the field measured spectra except for bands 1, 2, and 32. Quartz, calcite, diopside/hedenbergite, hornblende and microcline have been mapped by the emissivity image. Mineral mapping results agree with the dominant minerals identified by laboratory X-ray powder diffraction and spectroscopic analyses of field samples. Both of the results indicated that the atmospheric correction method and the combined temperature–emissivitiy method are suitable for TASI image. Carbonate skarnization was first found in the study area by the spatial extent of diopside. Chemical analyses of the skarn samples determined that the Au content was 0.32–1.74 g/t, with an average Au content of 0.73 g/t. This information provides an important resource for prospecting for skarn type gold deposits. It is also suggested that TASI is suitable for prospect and deposit scale exploration. |
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| Keywords: | Hyperspectral Thermal infrared remote sensing Temperature and emissivity separation Mineral mapping TASI |
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