A Preliminary Conceptual Model of Nubra Valley Geothermal System, Ladakh, J & k, India

The hot spring areas in Nubra valley, Ladakh, J&K located at Changlung, Panamik and Pulthang lie in a 30 km long NNW-SSE trending stretch parallel to and on the left bank of the Nubra river. These hot springs are confined to the Karakoram Granite which is in tectonic contact with the overlying Shyok volcanics.

The local meteoric water, which is Ca-Mg-HCO₃ type, alters to Na-HCO₃, type before it emerges as hot springs. This chemical alteration of descending local meteoric water may largely be attributed to rock-water interaction and resultant ion-exchange. Application of chemical geothennometries indicates that the chemical mass transfer between rock and water could have taken place at temperatures approaching at the most 200°C.

An attempted conceptual model of the Nubra valley hot spring system suggests that the three thennal areas of Changlung, Panamik and Pulthang are fed from an 'outflow' aligned parallel to the Nubra valley and following the regional hydraulic gradient. The hot water 'outflow' lying at a depth of more than 2 km within the Shyok volcanics is characterised by a decrease in the temperature and dilution of the fluid in the direction of the flow.

The chemistry of the discharging fluid is apparently influenced more by the type of rock reacted (granite or volcanics) than by the residence time and reservoir temperature.