Thermophysical Characterization of Major Rock Types and Subsurface Thermal Modeling in the Ladakh Himalaya, India: Implications for Geothermal Energy

The growing urgency of global atmospheric decarbonization and reaching net zero carbon emission underscores the importance of shifting our dependency from fossil fuels to relatively cleaner renewable resources. Though India’s average annual CO₂ emission growth from fossil fuels decreased from 6.4 % (2005-2014) to 3.6% (2015-2024) in recent times, India still stands as the third largest emitter of carbon at 3.2 billion tonnes per year (2024), reflecting the importance of expanding its renewable energy portfolio. Among the renewable energy resources, geothermal energy, which uses the natural heat stored inside the Earth, holds considerable potential for India, particularly along the Himalayan belt. The Ladakh Himalaya, which forms the northwestern sector of the India-Eurasia collision zone, is the focus of the current study. Ladakh is considered a highly promising geothermal province due to its active tectonics, crustal deformation, and widespread occurrences of numerous hot springs, like Puga, Chumathang, Panamik, Changlung, and Demchok where temperature reaches up to 90 ^oC. However, despite its strong geothermal potential, the region has limited subsurface thermal characterization, which poses challenges for effective resource assessment and sustainable exploitation.

This study presents an integrated approach that combines field and laboratory based geophysical datasets and geodynamic context to improve understanding of subsurface thermal structure for sustainable geothermal assessment. A comprehensive thermophysical dataset including thermal conductivity, porosity, density, specific heat capacity and radiogenic heat production has been generated in the present study from representative rock types. These include granitoid, sandstone, limestone, ophiolite, phyllite, schist and gneiss belonging to different geological formations such as Higher Himalayan Crystalline, Zanskar Formation, Lamayuru Formation, Indus formation, Ladakh Batholith and Khardung-Shyok Formation. Temperature measurements are carried out in boreholes for determining geothermal gradient, which is essential for calculating surface heat flow. These parameters serve as crucial inputs and boundary conditions, along with the available geological and geophysical information for constructing numerical thermal model and the quantification of crustal heat generation.

The thermal modelling simulates temperature distribution with depth and enhances the understanding of the lithospheric thermal structure of Ladakh, helping to delineate prospective zones for geothermal energy exploration. This work demonstrates the value of multi parameter geomodelling to transform sparse field observations into a robust geothermal assessment. The outcomes significantly contribute to future clean energy strategies, support a promising pathway towards global energy transition to achieve decarbonization goals and provide a framework for regional energy security of a remote mountainous region like Ladakh.   

Keywords: Geothermal energy; Heat flow; Thermal conductivity; Radiogenic heat production; Thermal modelling; Ladakh Himalaya.