Geothermal areas in Orissa and Bihar

The geothermal areas of Orissa and Bihar occur within an ENE-WSW lineament zone which is an extention of Son-Narmada-Tapti lineament. In Orissa the hot springs are located in Attri, Tarbola and Athamalik in the Puri and Dhenkal districts. (Fig. 9). The temperature of the hot springs ranges from 50 to 66 °C and the flow rate is 2 litres/s ec. The thermal manifestations at Tatta and Jarom in Bihar occur close to the hot spring belt of Surguja district of M.P. The temperature of the hot springs vary from 50 to 65 °C. The Surajkund hot springs have a temperature range of 47 C to 88 °C with a cumulative discharge of about 4.1 litres/second.

1.2.1 Geology

The thermal manifestations of Attri, Tarabola and Athamallik are located withing the Eastern Ghat province represented by granites, charaockites and kondalite suit of rocks.

Tarabola hot springs occur very close to the intersection of two major lineaments of which one is trending NE-SW and extending from Tattapani to Tarabola and the other trending NW-SE and extending from Athamalik to south of Attri. The Athamallik hot spring is located very close to the Mahanadi river at the contact between the Archeans and Gondwana rocks and occurs at the intersection of two major fractures trending NW-SE and NNE-SSW.

x

I \ X V« «

\ \

V x.

WEST BENGAL MADHYA PRADESH

SCALE

50 0 50 100 150

ANDHRA PRADESH

INDEX

ALLUVIUM (QUATERNARY)

] RAJMAHAL TRAPS {JURASSIC JRETACEOUS) GONDWANAS ( P A L A E O Z O I C / M E S O Z O I C )

CRYSTALLINES METAMORPHICS AND SEDIMENTARIES (ARCHAE A N/ PROTEROZOIC )

MEGALINEAMENT

INTERMEDIATE/MINOR LINEAMENT

FIG. 9. Thermal springs of Bihar, Orissa and West Bengal.

72

The thermal manifestation at Tatta and Jarom occur in ENE-WSW trending belt. The Tatta hot springs is located within a fault zone across the rocks of Barakar formation. The Jarom hot spring is located at the intersection of three fractures trending ENE-WSW, N-S 7.2.2. Geochemistry

The chemistry of thermal waters in Orissa is characterised by very low sulphate but high sodium and chloride contents (Na-Cl type water). High Na and Cl could be due to marine influence and negligible SO⁴ due to bacterial reduction of SO⁴ but H²S smell is found in some of these springs. In the relative Cl, SO⁴, HCO³, plot (Fig.4) the hot spring samples fall close to the Cl corner. The chemistry of thermal waters of Bihar (Tatta, Jarom, Surajkund etc.) are of the Na-HCO³-Cl-SO⁴ type, or similar to the thermal waters of the Tattapani geothermal area. On the Cl, SO⁴, HCO³ plot the hot springs samples fall near those of hot water drilled well samples of Tattapani area. Surajkund hot springs have high F content (20 ppm).

7.2.3 Gas chemistry

The results of the gas analysis in moles % of the samples collected from hot springs in Orissa are given in Table 3.

Table 3. Gas analysis (moles %) of hot springs in Orissa

Attri Tarabola Athamallik

H2

He N2

CH4

CO² H2S NH³ CO

1.46 32.05

4.15 61.40 0.94 0.01

~

0.06 7.85 4.79 86.79

0.48 0.02

••

0.35 22.85

0.05 76.36 0.37 0.02

™

From the table it is evident that CO² and N² are the main gas constitutents.He is present up to 1.46 % in Attri spring. The hot springs in Bihar arehigh in He, 3.9 % at Surajkund.

7.2.4 Geothermometry

Using the silica and potassium - magnesium geothermometer the reservoir temperature has been computed and the results are given in Table 4.

Table 4. Geothermometry temperatures of hot spring in Bihar and Orissa Location Measured Temperature computed, °C

temperature,°C chalcedony¹³¹ K-Mg^[4J Tatta

Jarom Surajkund Attri Tarabola Athamallik

65 57 88 57 66 59

97 135 122 107 94 107

98 112 122 103 94

-Thus the reservoir temperature range from 100 °C - 135 °C for Tatta, Jarom, Surajkund group of springs and from 95 °C- 110 °C for Attri, Tarabola, Athamallik group of springs.

7.2.5 Isotope study: Orissa hot spring locality

Samples from hot springs, cold springs, hand pumped shallow wells and borewells were sampled hi April 1991 and analysed for ²H and ¹⁸O. The results obtained are presented as ÖD - 518O and 818O - Cl plots (Figs. 10 & 11). From the ÔD - o'8O plot it can be seen that the composition of the hot springs from Athri and Kesodit are generally enriched in the heavy isotopes compared to the cold springs. This may be due to evaporation effect.

However, the thermal and non-thermal waters from Athamallik show similar ÔD and 8¹⁸O values. The hot springs fall near the meteoric line showing that they are of meteoric origin.

In the o^!8O - Cl plot the thermal and non thermal-waters show some correlation in the case of Attri samples. These samples are located near the coast and their salinity is due to supply from marine groundwaters. In the Athamallik samples even though the thermal waters have higher chloride compared to non- thermal waters, there is no change in the 6¹⁸O content.

Athamallik is located away from the coast and Cl in these waters could be derived from the rock with which the water interacts.

All the hot spring samples in Bihar fall near the meteoric line consistent with their meteoric origin. Except for hot springs from Surajkund and Kesodit the other hot springs from Tatta, Jarom, Duari and Bagodar have 5D and 5^I8O values similar to non-thermal waters.

(Fig. 12). Hot spring samples from Surajkund and Kesodit are slightly enriched compared to non-thermal waters possibly due to evaporation.

1.2.6 Discussion and conclusions

The hot springs of Orissa and Bihar occur in the ENE-WSW lineament zone which is an extension of the zone running through Tatapani. The chemistry of hot spring samples of Bihar are similar to Tatapani geothermal waters. The hot springs of Orissa are high in Na and Cl due to supply from a marine source. The 6¹⁸O of Attri thermal and non-thermal waters correlate with chloride showing some sea water contribution. In Athamalik which is away from the coast the high Cl content of hot springs is explained by rock leaching. The isotopic composition of the hot spring sample from Surajkund is similar to the hot springs of Tattapani.

74

6D

«1

0-

-10-

-20-

-30-

.40-

-50-400

300 CLa

•oHi

o200

100

© A 6 "

® A 5

H { T) TARABOLA

Q (A) ATTRf ATHAMLLIK

-6 To TA TI -2 -1 0 ,1 ,2 5*0 (%o)

FIG. 10. 5D-5¹⁸O plot of samples from hot spring localities in Orissa.

A 06

V A T h ?

OA9

0 A T T R I û DUARI V ATHMALIK

-8 -7 -6 -5 -« -3 -2 -1 0 tl ,2 6180(%o)

FIG. 11. o'⁸O-Cr relationship of hot springs and TW waters from Orissa.

+100

-CO

-10-

-20-

-30-

-40-

-50-

-60-D 7 0

DUARI V BAGODAR

& KESODIH

Q TATTA O SURAJKUND

7r r

6 ^—r_ 5

6180 -3

—r~

-2 -1 0

FIG. 12. SD-^5I8O plot, Bihar.