Geochemical Characterization and Geothermometry of the Geothermal Springs of Northwest India

Abstract:

The Himalayan collision zone between India and Asia hosts an active geothermal province that spans the border from India into Tibet. Despite significant exploration, commercial development thus far in India is limited to modest use of hot water for heating greenhouses. We sampled nine hot springs in Northwest India, from the Karakoram Fault, across the Indus-Yarlung Suture Zone, to the Main Central Thrust. We analyzed major cation and anion chemistry using ICP-OES. Calcium ranges from 1-220 ppm, potassium from 4-110 ppm, magnesium from 0-60 ppm and sodium from 70-440 ppm. These values are similar to samples analyzed by the Geological Survey of India in previous decades. Preliminary reservoir temperatures calculated using the Fournier & Potter Na-K-Ca-Mg geothermometer range from 100–260°C. No correlations with geologic structure or location across the Himalayan orogen are apparent, and springs located within a few tens of km of each other have apparent temperatures differing by a factor of two. However, these classical geothermometers are subject to large uncertainty in cases where gas has been lost or where there has been dilution of the waters from depth with surface waters. We will use Lawrence Berkeley National Laboratory’s multicomponent geothermometry code, GeoT, to improve the temperature estimation for each geothermal site. Even if reservoir temperatures are not high enough for electricity generation, these springs have the potential to provide cheap heating and cooling for the local communities. We plan to collect additional water samples in neighboring Tibet in the future.