Sub-surface paleochannel detection in DeGrussa area, Western Australia, using thermal infrared remote sensing

摘要

Thermal Infrared (TIR) remote sensing measures emitted radiation of Earth in the thermal region of electromagnetic spectrum. This information can be useful in studying sub-surface features such as buried palaeochannels, which are ancient river systems that have dried up over time and are now buried under soil cover or overlying sediments in the present landscape. Therefore they have little or no expression on the surface topography. Study of these paleochannels has wide applications in the fields of uranium exploration and ground water hydrology. Identifying paleochannels using remote sensing technique is a cost-effective means of narrowing down search areas and thereby aids in ground exploration. The difference in thermal properties between the paleochannel-fill sediments and the surrounding bed-rock is the key to demarcate these channels. This study uses five TIR bands of daytime Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) L1A data for delineation of paleo-systems in the DeGrussa area of the Capricorn Orogen in Western Australia. The temperature-emissivity separation algorithm is applied to obtain kinetic temperature and emissivity images. Sharp contrasts in kinetic temperature and emissivity values are used to demarcate the channel boundaries. Profiles of topographic elevation, temperature and emissivity values are plotted for different sections of the interpreted channels and compared to distinguish the surface channels from sub-surface channels, and also to interpret the thickness and nature of the paleochannel-fill sediments. The results are validated using core-drilling lithologs and field exploration data.