Radon, helium and uranium survey in some thermal springs located in NW Himalayas, India: mobilization by tectonic features or by geochemical barriers?

Abstract

Radon, helium and uranium measurements have been carried out in hot water springs in the Parbati and Beas valleys of Himachal Himalaya. Most of these hot springs are known as famous pilgrimage centers. The activity of dissolved radon in the liquid phase is found to vary widely, by an order of magnitude, between 10 and 750 Bq L(-1), whereas, the dissolved helium content in these thermal springs varies between 10 and 100 ppm. The uranium contents are low and vary from <0.01 to 5 microg L(-1). The measured values of radon, helium and uranium are possibly controlled by structural geology, namely the presence of pervious fault systems, and by the lithology of the leached host rocks. Redox-potential geochemical barriers cause the mobilization of uranile ions in solution (UO2+); the most plausible hypothesis is when the conditions are oxidising, confirming the importance of physico-chemical conditions up to the supergenic environment, to control the fluid geochemistry of the U-He-222Rn system. Some evidence is available from both geothermometric considerations and geochemical data which will be reported elsewhere, whereas the present study is focused on U decay series-noble gas geochemistry. The first analysis of collected 3He/4He data is consistent with a crustal signature at the studied thermal springs.

Geochemistry of thermal waters along fault segments in the Beas and Parvati valleys (north-west Himalaya, Himachal Pradesh) and in the Sohna town (Haryana), India

“…A major NNW-SSE reverse fault system has been identified in Kasol and other lineaments have been postulated northward into the Beas Valley and near Manali (Walia et al, 2005a, b). A large NNW-SSE anticline (the Beas anticline) and a complementary syncline (the Handogi syncline) have folded the Shali-Rampur, Chail and Jutogh units, with another NNW-SSE anticline lying in the central part of the Shali-Rampur zone (Misra and Tewari, 1988).…”

“…The quite low salinity of these waters is the consequence of i) their circulation through the unaltered Rampur quartzite, which represents a limiting factor for the groundwater evolution and ii) their fast circulation along fault segments, which prevents any appreciable water-rock interaction. The slightly higher content of dissolved salts at Manikaran with respect to Kasol may be ascribed to the presence of river terraces and alluvial cones, which suggest a more efficient water-rock interaction and subsequent salt leaching relatively to Kasol (Alam et al, 2004;Walia et al, 2005a).…”

“…Geochemical studies of thermal springs from India have been carried out in the past by several authors (Gupta et al, 1975;Giggenbach et al, 1983;Guha, 1986;Chandrasekharam and Antu, 1995;Pandey and Negi, 1995;Gupta, 1996;Minissale et al, 2000Minissale et al, , 2003Alam et al, 2004;Walia et al, 2005a). They found that these waters are generally associated with tectonic belts, midcontinental rifts, Cretaceous-Tertiary volcanism and regional fault zones.…”

“…The studied area is geographically located among the Manali, Kulu and Manikaran villages (Kulu District), along the Parvati and Beas valleys of the Indian Himalaya (Sharma, 1977;Misra and Tewari, 1988;Walia et al, 2003Walia et al, , 2005aWalia et al, , 2005b. The nature, distribution and disposition of the different geological units are the result of the structural and tectonic features imposed during, at least, three phases of deformation related to the Himalayan Orogeny (Gansser, 1964;Le Fort, 1989;Sharma, 1998).…”

“…Other works (Choubey et al, 1997;Virk and Walia, 2000;Walia et al, 2003Walia et al, , 2005aWalia et al, , 2005b) focused on radon monitoring in waters and soils for health hazard assessment and as a tool for earthquake prediction studies. Few published studies have reported chemical (Gupta, 1996) and isotopic data (Giggenbach et al, 1983) of the thermal waters.…”