Remote sensing-based Identification of Potential Geothermal Zones in the Himalaya-Karakoram Orogenic Belt, Northern Pakistan

Abstract

Hot springs in the granitoid and gneissic complexes of the Himalaya-Karakoram orogenic belt indicate subsurface geothermal potential, which could help meet energy demand in this region with topographic and climatic extremities. However, challenging terrain and limited accessibility constrain extensive ground-based exploration. We have utilized satellite remote sensing to identify potential areas of interest at a reconnaissance scale. Alteration minerals such as alunite, kaolinite, illite, chlorite, and micas, identified through principal component analysis of ASTER SWIR-bands, indicate active and fossil zones of hydrothermal activity. Lineament density, derived from SRTM data, shows high lineament zones associated with faults and granitoid outcrops. XRD analysis of altered samples collected from these areas of interest confirm weak to moderate alteration of biotite, K-feldspar, and plagioclase in the granitoids and gneisses. The alteration intensity increases in shear zones and suggests fracture-assisted fluid interaction. We conclude that the granitoids and gneisses (enriched with radiogenic elements) are subsurface reservoirs of the hot springs operated by topographic and fault-controlled groundwater systems. We recommend further detailed ground-based exploration in our identified potential zones for their geothermal assessment.