Thermal inertia mapping and its application in mineral exploration: results from Mamandur polymetal prospect, India

Abstract

Thermal anomalies associated with ore-mineralization (Pb-Cu-Zn and Fe) were studied using thermal infrared data collected over Mamandur polymetal prospect, India, with the aid of satellite, field, and laboratory measurements. Day and night ASTER data were analysed in conjunction with field measurements to estimate thermal inertia of the ore body, altered zones and country rocks. Representative samples collected from field were also analysed for thermal conductivity, diffusivity, and inertia using a self-fabricated setup. Spatial changes in thermal inertia were mapped by look up table (LUT) and advanced thermal inertia mapping (ATIM) approaches. Mineralized zones show very high thermal contrast (delta T) both in field (15-25 degrees C) and satellite data (14.9-16.9(o)C). They also exhibit the lowest thermal inertia in field-(2118-5474 J m(-2) K-1 s(-1/2)) and satellite-based (3783-4037 J m(-2) K-1 s(-1/2)) measurements. In non-mineralized areas, acidic rocks (granite, migmatite and granite gneiss) have lower inertia than basic rocks (basic granulite, dolerite and charnockite). Results estimated by LUT and ATIM approaches correlate very well at satellite (R-2 = 0.97) and field (R-2 = 0.89) scales. Similarly, field- and satellite-based results also have good correlation (R-2 = 0.69-0.72). This study illustrates the potential of thermal inertia mapping in delineating ore bodies and deciphering the lithological changes even under veneer of soil.