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Isotopic and chemical composition of Parbati Valley geothermal discharges, north-west Himalaya, India

W.F. Giggenbach·R. Gonfiantini·B.L. Jangi·A.H. Truesdell
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Abstract

The isotopic compositions of the waters discharged from Parbati Valley geothermal areas indicate a higher altitude meteoric origin, with discharge temperatures reflecting variations in the depth of penetration of the waters to levels heated by the existence of a ‘normal’ geothermal gradient. On the basis of mixing models involving silica, tritium, discharge temperatures and chloride contents, deep equilibration temperatures of 120–140°C were obtained for Manikaran, possibly reaching 160°C at even greater depth. Geothermometers based on sulfate-water 18 O exchange and gas reactions point to similar temperatures. Exceptionally high helium contents of the discharges correspond to apparent crustal residence times of the waters in the order of 10–100 Ma; relative nitrogen-argon contents support a largely meteoric origin of the waters with a possible fossil brine, but no detectable magmatic component.

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W.F. Giggenbach, R. Gonfiantini, B.L. Jangi, A.H. Truesdell. 1983. Isotopic and chemical composition of Parbati Valley geothermal discharges, north-west Himalaya, India. https://doi.org/10.1016/0375-6505(83)90030-5

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