Advanced remote lithologic mapping in ophiolite zone with ASTER multispectral thermal infrared data

Abstract

ASTER is the first and the only satellite-borne imaging sensor with a capability of multispectral observation in the thermal infrared (TIR; 8 to 12 microns) spectral region at spectral, radiometric and spatial resolutions adequate for regional geological study. Most of the methods for lithologic or mineralogic mapping with multispectral TIR remote sensing data proposed so far premises to apply emissivity data as input, but methods applying Level-1B radiance at the sensor data without atmospheric corrections have an advantage in data productivity. Another advantage of the methods for Level-1B is the extendibility for Level-3A data, enables easy fusion with GIS. The author proposed Quartz Index (QI), Carbonate Index (CI) and bulk SiO2 content Index (SI) for ASTER-TIR data with theoretical and practical analyses for the applicability of Level- 1B data, improved the indices, and showed that the lithologic mapping with the indices for Level-1B data is stable against the variation of temperature and atmospheric conditions. In this paper, the method is applied to several Level-3A data scenes observing a part of Yarlung Zangbo ophiolite belt in Tibet, and the results are compared with the existing geological information to show the effectiveness of the method for achieving lower cost and higher accuracy in geological mapping, especially in mapping ultramafic rock bodies.