Thermal springs in the Alaknanda valley, Uttar Pradesh, Northern India 2.2.7 Introduction

Thermal springs of Badrinath in Alaknanda valley and Tapoban in the Dauliganga valley are located at an elevation of 2000 - 3000 m above mean sea level, in the Himalayan terrain. The Badrinath hot springs are located at a higher elevation compared to the Tapoban hot springs. There are a dozen thermal springs clustered around 4 localities in the Tapoban area. The rocks in the Tapoban and Badrinath areas belong to the Central Crystallines. The thermal springs in Tapoban emerge in the Tapoban quartzite members. The quartzite and the underlying schist of the Helang formation form the shallow reservoir in the area [6]. The 76

A

o\

SCALE

0 1 Km.

2000m . _ _ m •

* Juwagwaro

\E

•2000 m F 2400m 2562m J

A\

ojugju

0Rini

Murunnao

INDEX JOSHIMATH GNEISS &SCHIST GAR H QUARTZITE

DHAK GNEISS & SCHIST TAPOBAN QUARTZITE HELANG SCHIST WITH

CALCAREOUS INTERCALATION

<*888& SHEAR ZONE

•^-F FAULT 29- FOLIATION Ë S 2000m SPOT HEIGHT

ABOVE M S L + THERMAL SPRING

^ © BORE HOLES o

O

O<r o_

1 A G W - 6 BORE HOLE ( H O T ) 2 A G W - 3 „ ( H O T ) 3 A G W - 2 .. ( H O T )

4 HOT SPRING ON THE LEFT BANK OF TAPOBAN NALA 5 TAPOBAN NALA

6 COLD SPRING NEAR OLD SCHOOL

7 COLD SPRING 100 M. AWAY BHANGYAL BRIDGE FIG. 13. Tapoban geothermal area, district Chamoli, Uttar Pradesh.

maximum temperature of the hot springs is 65 °C. Three exploratory bore holes (Fig. 13) were drilled by the Geological Survey of India (AGW-2, AGW-3, AGW-6) and from AGW-3 thermal water discharges at 13 litres/sec at a temperature of 90 °C. Mid tertiary granite is known to occur in deeper zones (~500 m) and hence the possibility of still younger phases of acid magmatism, not yet exposed by erosion, cannot be ruled out. Such acid magmatic bodies may be contributing heat to the geothermal system.

2.2.2 Major ion chemistry

The hot spring and hot water well samples of Tapoban are of the Ca (HCO³) type, whereas the Badrinath hot springs are NaCl type waters. On the relative Cl, HCO³ SO⁴ plot (Fig.4) the Tapoban thermal waters fall near the HCO³ corner whereas the Badrinath hot springs fall near the chloride corner. The drilled well thermal water sample from AGW-3 (Tapoban) has a higher HCO³ content than the hot spring in the area.

2.2.3 Minor and trace ions

Relative Li, Rb, Cs concentrations for the Tapoban and Badrinath thermal waters has been plotted in Fig. 5. The Li/Cs ratios for Tapoban and Badrinath spring discharges are similar. There is a small increase in the Li/Cs of hot water drilled well sample compared to spring sample of Tapoban.

Relative Cl, Li and B contents in thermal water of Badrinath and Tapoban show that Badrinath hot springs fall near the chloride corner with low B/C1 ratio (Fig. 14). The Tapoban thermal waters fall nearer the B corner with higher B/C1 ratio probably due to presence of shales in the reservoir, but such rocks are known to be relatively rich in B.

Cl/100

O WELL O SPRING

80 0.01

Of/o —

20 40 60 '/„-B" 80

FIG. 14. Relative Cl, Li and B contents in thermal waters from Tapoban (TN) and Badrinath (BD).

78

2.2.4 Gas chemistry

The results of the chemical analysis of gas samples collected from Badrinath and Tapoban hot springs [7] are as follows:

Table 5. Gas Analysis (moles %) of Badrinath and Tapoban Hot springs ÏJ He 0 N CH N H C O Tapoban H.S.

Badrinath H.S.

tr tr

0.09 0.01

2.43 tr

18.96 tr

tr tr

tr tr

78.52 99.99 The results show that CO2 is the main gas component in the above areas.

2.2.5 Geothermometry

The reservoir temperature of Tapoban and Badrinath systems have been computed using the silica geothermometer. The results are presented in Table 6.

Table 6. Reservoir temperature of Tapoban and Badrinath system Temperature Temperature computed °C

measured °C Chalcedony[3]

Tapoban H.S.

Tapoban Borewell Badrinath H.S.

59 90 55

88 99 120

Thus the reservoir temperature for Tapolban geothermal water is 100°C and for Badrinath geothermal waters is 120°C.

2.2.6 Isotope study

The oD and 5¹⁸O results have been plotted in Fig (15). The ÔD, 5¹⁸O values of the cold springs surface waters etc. were used to obtain the local meteoric water line. The regression line of the local meteoric water line had an equation of ÔD =7.7 6¹⁸O + 13.0 (r²

= 0.94, n=7). The hot spring and the hot water drilled well samples fall approximately on the local meteoric line showing no oxygen-18 shift.

The hot water well sample AGW-6 has a similar isotopic value as AGW-3. Hence lower temperature of discharge from AGW-6 may be due to cooling by conduction rather than due to mixing of near surface water.

The oD and 5¹⁸O values of the hot spring and the hot water borewell samples of Tapoban and Badrinath are low compared to the cold springs. They indicate a higher altitude of recharge for the hot springs compared to the cold springs. The altitudes of recharge of thermal waters have been estimated using D-altitude plot for the Himalayas. The D - altitude plot was constructed from snow samples collected from different altitudes in the Himalayan

-20-1

-40-s o

W

o

o

•80-N

«O

•100-

-120-0²H = 7.70¹⁸0 + 13 X (r2 = 0.94; n = 7>" ^X

METEORIC WATER LINE

D *

.***** SURFACE WATER, BADRINATH DDDDDHOT WATER SPRING, BADRINATH AAAAACOLD WATER SPRING, BADRINATH

••••• HOT WATER SPRING. TAPOBAN BBHBBHOT WATER WELL, TAPOBAN

WATER SPRING. TAPOBAN

-16 -14 -12 -10 -8^{——l—————r}-12 ^T

(5

¹⁸

0 o/oo SMOW

-6

FIG. 15. 8 H-o¹⁸O graph of samples, Badrinath and Tapoban geothermal areas.

ranges in Himachal Pradesh and Ladakh (J & K) [5]. The hot spring and hot water borewell in Tapoban have a maximum altitude of recharge of 2700 m while the altitude of recharge for the hot spring in Badrinath is 3200 m.

The tritium values of the hot spring and hot water borewell samples in Tapoban are in the range of 21-27 TU which are higher than the values of cold springs 1 9 - 2 3 TU. The AGW-3, hot water borewell sample (temp. 91 °C) shows the highest tritium value of 27.4 TU.

The tritium level of Badrinath hot spring is 7.7 TU. The present level of tritium in New Delhi which is the nearest station on the IAEA/WMO network is about 5 TU. Hence the high

3H levels observed in hot springs/hot water wells and cold spring samples show the presence of bomb tritium. The tritium value of the Himalayan stream and rivers are 20 TU and they get contributions from snow melt which has bomb tritium. Using a piston flow model and tritium out put for New Delhi the residence time of the Tapoban hot waters is about 20 years.

2.2.7 Discussion and conclusions

The thermal waters from Badrinath are of the NaCl type while those from Tapoban are of the Ca (HCO3)2type. Gas samples from both Badrinath and Tapoban hot springs have high CO2. Samples of carbonates deposited by artesian thermal waters flowing from boreholes AGW-2, AGW-3 and AGW-6 in Tapoban show 013C between 1.3 to 4.3 % with

80

NS.LWNW E S E _ L S W

2750-

2500-2 2500-2

BO-2000'

1750-

1500-

1250-INDEX

CENTRAL CRYSTALLINES WITH ACIDIC INTRUSIVE BODY

b I JOSHIMATH GNEISSES AND SCHISTS GARH QUARTZITE

'Id,: DHAK GNEISS AND SCHIST TAPOBAN QUARTZITE

UNDIFFERENTIATED

CENTRAL

.CRYSTALLINES . „ (DIFFERENTIATED)^

I f I HELANG SCHISTS . ____

80° C SPOT TEMPERATURE HBORE HOLE THERMAL SPRING (65'C) U ™ LOWING^

i/

AGW-3

1000m Above

MSL

- 2 k m

2 0 k m

FIG. 16. Model of Tapoban geothermal system, district Chamoli, Uttar Pradesh.

respect to PDB suggesting that the CO² in the fluids has come through dissolution of marine carbonate rocks. Thermal waters from Tapoban and Badrinath fall near the local meteoric line showing negligible oxygen -18 shift. Hot spring and hot water well samples of Tapoban and Badrinath are more depleted in oD and 8¹⁸O than the cold springs in the area showing that the thermal water have higher altitude of recharge compared to the non-thermal waters. Fig.

16 show the model of Tapoban geothermal system [5]. The model visualises recharging waters from elevations > 3000 m getting heated from two sources viz. the geothermal gradient and from cooling acid magmatic instrusives at depths.

Acknowledgement - Acknowledgements are due to Mr. U.L. Pitale, Director, GSI, Geothermal Division (Central Region) for work in Tattapani and Mr. S. C. Sharma, Director, GSI, Geothermal Division (Northern Region) for studies in Badrinath and Tapoban areas. We thank our colleagues Mr. U.K. Sinha and Mr. T.B. Joseph for the tritium measurements. The present investigation was carried out within the framework of the IAEA Coordinated Research Programme for Africa, Asia and the Middle East on the Application of Isotope and Geochemical techniques in geothermal exploration.

References

[1] SHANKAR R., THUSSU, J.L., PRASAD, J.M., Geothermal studies at Tattapani Hot spring area, Surguja district Central India, Geothermics 16 (1987) 6 1 - 7 6

[2] THUSSU, J.L., PRASAD J.M, SAXENA, R.K., GYAN PRAKASH, MUTHURAMAN, K.,Geothermal energy resource potential of Tattapani Hot spring belt, District Surguja, Madhya Pradesh, Records of GSI 115 (1987) 30 - 55.

[3] TRUESDELL A.H.,"Stable isotopes in hydrothermal systems" Fluid Mineral Equilibrium in hydrothermal systems - Reviews in Economic Geology Vol. 1 (Robertson, J.M. Ed.) The Economic Geology Publishing Co. USA (1984) 129 - 141

[4] GIGGENBACH W.F., GONFIANTINI R., JANGI B.L., TRUESDELL A.H., Isotopic and chemical composition of Parbati valley Geothermal discharges, North-West Himalaya, India, Geothermis 12 (1983) 199-222.

[5] NAVADA S.V., RAO, S.M., Isotope studies of some geothermal waters in India, Isotopen praxis 27 (1991) 153 - 163.

[6] GEOLOGICAL SURVEY OF INDIA, Geothermal Atlas of India, Special publication 19, (1991) 38 - 45.

[7] SINGH J.R.,Chemistry of geothermal gases: Collection, Analysis and some Indian case studies, Indian Minerals, 43, (1989) 7 - 18.

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ISOTOPE STUDY IN GEOTHERMAL FIELDS IN JAVA ISLAND

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