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
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Geochemical Journal, Vol. 43, pp. 65 to 76, 2009 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 D. CINTI,1* L. PIZZINO,1 N. VOLTATTORNI,1 F. QUATTROCCHI1 and V. WALIA2 1Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143 Roma, Italy 2National Center for Research on Earthquake Engineering (NCREE), National Applied Research Laboratories, Taipei - 106, Taiwan (Received January 28, 2008; Accepted October 15, 2008) A geochemical survey on thermal waters discharging in the Beas and Parvati valleys (Kulu District, Himachal Pradesh) and in the Sohna town (Gurgaon District, Haryana) was carried out in March 2002. The Beas and Parvati area is character- ized by regional seismogenetic fault segments, thrusts and complex folded structures where deep fluid circulation occurs. Thermal springs have temperatures varying between 35°C and 89°C. The wide range of surface temperatures and water chemistries suggest the mixing, at various degrees, between a deep saline end-member and a shallow freshwater. Based on the high salinity and the enrichment in halogens (Cl, Br), B and Li, the contribution of the deeper end-member seems to be larger for Kulu and Kalath relative to Manikaran and Kasol. Moreover, a large input of crustal volatiles (He, CO2, H2) is δ13 observed for Kulu and Kalath waters. The high dissolved CO2 content and its carbon isotopic composition ( CTDIC = –2.87 and –7.49‰ vs. PDB for Kulu and Kalath, respectively) point to a deep, prevalent thermo-metamorphic provenance of the carbon dioxide. A general shallow (i.e., organic) origin of carbon dioxide is suggested for Kasol and Manikaran. The estimated deep temperatures based on the quartz geothermometer provide values ranging between 93–114°C for all the thermal waters of the Beas and Parvati valleys. The Sohna thermal spring emerges at 42°C from joints of the seismogenetic Sohna fault. A Na–Cl–HCO3 composition characterizes this water with very low contents of all the selected minor and trace elements. High dissolved helium content points to a prolonged deep circulation, whereas calculated δ13C– CO2 (–14.23‰ vs. PDB) is indicative of the general shallow origin of carbon dioxide. The estimated deep temperatures are close to the discharge ones, not providing any valuable information about the temperature of the deeper reservoir. Keywords: thermal waters, Himachal Pradesh, carbon isotopes, salinity, dissolved gases focused on the geochemical analyses of thermal springs INTRODUCTION of the Beas and Parvati valley geothermal system Geochemical studies of thermal springs from India (Himachal Pradesh, province 1) and that of Sohna (prov- have been carried out in the past by several authors (Gupta ince 2). et al., 1975; Giggenbach et al., 1983; Guha, 1986; Previous studies of the Himachal Pradesh geothermal Chandrasekharam and Antu, 1995; Pandey and Negi, sub-province were focused mainly on the famous ther- 1995; Gupta, 1996; Minissale et al., 2000, 2003; Alam et mal springs of Manikaran and Kasol along the Parvati al., 2004; Walia et al., 2005a). They found that these Valley (Alam et al., 2004; Chandrasekharam et al., 2005), waters are generally associated with tectonic belts, mid- with the aim to characterize the geothermal resources with continental rifts, Cretaceous–Tertiary volcanism and re- respect to their suitability for electric power production. gional fault zones. More than 400 thermal springs have Other works (Choubey et al., 1997; Virk and Walia, 2000; been analyzed and are part of the following seven major Walia et al., 2003, 2005a, 2005b) focused on radon moni- geothermal provinces (Gupta et al., 1975; Pandey and toring in waters and soils for health hazard assessment Negi, 1995): 1) the tectonic belts of Himalaya, 2) the and as a tool for earthquake prediction studies. Few pub- Sohna fault zone, 3) Cambay, 4) the Son–Narmada–Tapi lished studies have reported chemical (Gupta, 1996) and lineament (namely, SONATA), 5) the West Coast fault isotopic data (Giggenbach et al., 1983) of the thermal zone, 6) Godavari and 7) Mahanadi. The present work is waters. Scarce data exist for the Sohna thermal district (Gupta et al., 1975; Singh, 1996). This paper presents results obtained in the frame of *Corresponding author (e-mail: [email protected]) an Indo-Italian collaborative research program focused Copyright © 2009 by The Geochemical Society of Japan. on fluid geochemistry along fault zones (Walia et al., 65 Fig. 1. a) Geological sketch-map of the studied area, showing the water sampling locations; b) geological cross section along A– A1 and B–B1 illustrating the geological structure of the area. Geological map and section are modified after Misra and Tewari, (1988). Legend: 1) fine grained banded gneiss; 2) foliated micaceous quartzite; 3) biotite schist with foliated micaceous quartz- ite; 4) garnetiferous biotite-phyllonite and schist; 5) intrusive Mandi granite; 6) sericite-chlorite phyllite, quartzite, mylonitized gneiss, quartz porphyry, carbonaceous slate with thin bands of limestone; 7) intrusive Bandal granite; 8) Rampur quartzite; 9) volcanics; 10) dolomite, limestone, quartzite, volcanics, shale and slate; 11) fine grained micaceous sandstone, purple-green clay, claystone and micaceous siltstone. 2005a). The study is specifically aimed at defining the this paper is to reconstruct the circulation paths and the origin and evolution of the emerging fluids based on ma- water-rock interaction processes, as well as to clarify the jor, minor and trace elements, dissolved gas contents and role of active fault systems in affecting the groundwater δ13C–TDIC isotopic signatures. Furthermore, the goal of geochemistry. 66 D. Cinti et al. GEOLOGICAL, STRUCTURAL AND HYDROGEOLOGICAL SETTINGS Beas and Parvati valleys 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., 2003, 2005a, 2005b). The nature, distribution and dispo- sition 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). Four major tectono-stratigraphic units, each bounded by deep-seated thrusts, may describe the geology of the area: the Shali Formation, the Rampur Formation, the Chail Group and the Jutogh Group (Fig. 1a). All these forma- tions include various lithologies ranging from low to high- grade metamorphites to granitic bodies related to a re- gional subduction tectonic regime. The Rampur Forma- tion tectonically overlays the Shali Formation along the Garsa Thrust (Fig. 1b) and is made up of volcanites at the lower level and Rampur quartzite towards the top. The boundary between the Shali–Rampur Group and the low- grade metamorphites of Chail Group is the Chail Thrust. The Chail metamorphites are intruded by the Mandi Gran- Fig. 2. Geology of the Delhi and Aravalli Mountains regions ite and are tectonically overlain by the huge succession in northwestern India (modified after Gupta et al., 1997). of medium-grade metamorphites of Jutogh Group, sepa- rated along the Jutogh Thrust (Misra and Tewari, 1988). A major NNW-SSE reverse fault system has been iden- tified in Kasol and other lineaments have been postulated groundwater-bearing zones. In these areas, the aquifers northward into the Beas Valley and near Manali (Walia et are unconfined at relatively shallow depths, whereas con- al., 2005a, b). A large NNW-SSE anticline (the Beas an- fined and semi-confined aquifers prevail at higher depths ticline) and a complementary syncline (the Handogi (Walia et al., 2005b). In the metamorphites and granites, syncline) have folded the Shali–Rampur, Chail and Jutogh the presence of faults, fractures and joints generate sec- units, with another NNW-SSE anticline lying in the cen- ondary porosity and permeability, and provide preferen- tral part of the Shali–Rampur zone (Misra and Tewari, tial pathways for the infiltration of meteoric waters as 1988). well as for the upward migration of thermal fluids from High heat flow (>100 mW/m2) and geothermal gradi- depth. It is hypothesized that the waters descend very deep ents greater than 200°C/km have been recorded from wells down along the major structural faults and return to the drilled in the North-West Himalayan geothermal prov- surface after getting heated by the anomalous geothermal ince (Ravi Shanker, 1988). The source of the heat may be gradient (Sharma, 1977; Ravi Shanker, 1988). During related to crustal melting processes at shallow depth as- their rise towards the surface, they likely mix with mete- sociated with subduction and testified by the presence of oric freshwaters, resulting in dilution at various degrees. a large number of relatively young granite intrusions (Makovsky and Klemperer, 1999; Chandrasekharam et al., Sohna area 2005 and references therein). An alternative hypothesis The village of Sohna is located about 50 km south of is that the crust is anomalously enriched in U (and likely Delhi, in the state of Haryana. Precambrian meta- Th and K), as suggested by the numerous and important sediments of the Delhi Supergroup characterize the geol- U mineralizations (Das et al., 1979; Walia et al., 2005b), ogy of the area (Fig. 2). They are represented, from bot- contributing to the high regional heat flow (Rao et al., tom to top, by quartzites, mica schists and pegmatite 1976). intrusives of the Alwar Group and by argillaceous The highly porous and permeable fluvial and colluvial sediments (including shale, slate and siltstones), quartzitic deposits lying along the valley slopes in the form of fans, and cherty bands of the Ajaib Garh Group (Chakrapani, river terraces and old landslides constitute potential 1981). The rocks that are widespread at Sohna are quartz- Thermal waters from the Beas and Parvati valleys and the Sohna town in India 67 68 D.Cinti et al .