Hydrochemistry, geothermometry and origin of the low temperature thermal springs of South Konkan region, India

• Published in: Geothermics Vol. 90; p. 101997
• Main Authors: Das, Prasenjit, Maya, K., Padmalal, D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2021; Elsevier Science Ltd
• Subjects: Anthropogenic factors; Enthalpy; Evolution; Fault lines; Geochemistry; Geological faults; Geology; Geothermal power; Geothermometry; Groundwater; Heated water; Hot springs; Human influences; Hydrogeochemistry; Hydrogeology; Hydrologic data; Isotopes; Low temperature; Minerals; Reservoirs; South India; Stable isotope; Stable isotopes; Thermal spring; Thermal water; Trace elements; Warm water; Water analysis; Water sampling; Water springs; India; Hydrogeochemistry; Stable isotope; Thermal spring; South India; Geothermometry
• ISSN: 0375-6505; 1879-3576
• DOI: 10.1016/j.geothermics.2020.101997

•Geochemical and isotopic composition of two low temperature thermal springs in south Konkan region, South India were studied.•These thermal waters are of Na-HCO3 type peripheral waters.•Geochemical classification indicate dissolution of silicate minerals controls chemical composition of this thermal water system.•Stable isotope composition indicate meteoric origin of thermal waters without isotope exchange by interaction with host rocks.•Results suggest that these thermal springs are most likely part of fault-controlled shallow hydrothermal system. The west coast of India is one of the important geothermal provinces that hosts many thermal springs of varying discharge characteristics. A total of twenty thermal springs have been reported in this region falling into two different suites of geological formations. Two low temperature geothermal springs located in the south Konkan region were studied with the objectives (1) to understand the geochemical evolution, (2) to identify the recharge source and (3) to propose a reservoir temperature. The hydrogeological and geochemical investigations were carried out on two geothermal springs, viz. Bandaru and Irde, both located in the Dakshina Kannada district of the Karnataka state, India. In this region, low-temperature geothermal activity has been reported in the form of the evolution of warm water from thermal spring systems with a notable presence of faults/lineaments in the geological formation. These faults enable the upward flow of geothermally heated water. The hydrochemistry of water samples was analyzed to determine the dominant hydrogeochemical processes in the region. These thermal springs are categorised as Na-HCO3 type facies. The thermal water is of a moderately alkaline nature like other geothermal springs of the west coast of India. Based on the results for major and trace element concentrations it was found that the hydrochemical process was mainly controlled by the dissolution of silicate minerals with a marginal influence from anthropogenic activity. Evaluation of δD and δ18O stable isotope data suggested that the thermal springs and adjacent surface and groundwater were of meteoric origin. Reservoir temperature was estimated with Na-K-Ca, K2/Mg, quartz and chalcedony geothermometers. The results suggest that the reservoir under consideration is a low enthalpy reservoir with temperatures ranging between 55 and 86 °C.