The application of Advanced Spaceborn Thermal Emission and Reflection (ASTER) radiometer data for mineral exploration in Sri Lanka ; a case study from serpentinite deposit in Ussangoda.

Abstract

Ussangoda, located in southern most part of the Highland-Vij ay an boundary, is characterized by hydrothermally altered serpentine deposit associated with hematite rich clayey sand. This serpentinite body represents the ocean floor material that was emplaced along the boundary during the last stages of the closing up of the highland marine basin and subsequent collision of the two plates. High concentration of Cr and Ni of the Ussangoda Serpentinite are likely to be the most economic product and that can be used to extract Ni as in New Caledonia. Analysis of 15- band Advanced Spaceborn Thermal Emission and Reflection Radiometer (ASTER) data of the study area, aided by detailed field studies, shows that altered serpentine rocks which contains high amount of ferrous ions are laterally extensively spread. Ni, Cr and Ferrous ion cause distinctive absorption features at 0.4 pm, 0.55 pm and 0.55 - 0.57 pm respectively. Although the ASTER spectral resolution is not adequate to distinguish those minerals, band rationing method was successfully used to map serpentine deposit of the area. The adopted ASTER band-ratio images demonstrate the benefit of using ASTER remote sensing data for mineral exploration at low cost and with high accuracy. This method therefore can be used to explore more serpentine along Highland-Vij ay an boundary with their spatial extends. In this way, Remote sensing mineral mapping can be used as a powerful tool in the initial steps of ore deposit exploration in Sri Lanka.