Himalayan Geology, Vol. 38 (2), 2017, pp. 129-140, Printed in India
Hydrogeochemistry, stable isotope study and implication for the origin of geothermal springs in Northeast Kumaun Himalaya, India
DINESH S. CHAUHAN1*, RAJESH SHARMA1, SANTOSH KUMAR2
1Wadia Institute of Himalayan Geology, Dehradun 248001, India
2Centre of Advance Studies in Geology, Kumaun University, Nainital, India
*Present Address: 102, Janta Colony, Behind Rameshwer Nagar, Jodhpur (Raj.), India
*Email (Corresponding author): dinesh_geo@rediffmail.com
Abstract: The chemical characters and isotopic signatures of the geothermal springs neighbouring Chiplakot Crystalline Belt (CCB), northeast Kumaun Himalaya are studied to estimate their reservoir temperatures and for understanding their evolution. The water chemistry of these thermal springs namely Tapovan, Bhenti, Darr, Shera, Devibagar and Pangla attributes that they originate from different reservoirs. The silica thermometry reveals temperatures of their reservoir between 80 and 129°C, whereas the alkali thermometry provides unusual high reservoir temperatures. The water chemistry and δ18O‰ signatures imply involvement of chemically immature, meteoric water in their formation, and therefore application of alkali thermometry is unsuitable for estimation of their reservoir temperatures. The δ34S‰ values of the sulphur in the precipitates found at the aperture of some of these springs indicate a magmatic origin, however matching values of δ34S‰ obtained for the sulphides present in the adjoining area suggest that sulphur is likely derived from these sulphide minerals. The study invokes that the thermal water springs around CCB are evolved by heating of the percolating meteoric water in high geothermal gradient, their water-rock interaction is not well-defined and the sulphur in their precipitate is derived from the sulphide minerals present in the area.
Key words: Geothermal springs, Water chemistry, Stable isotopes, Kumaun Himalaya.
