Rit (Vísindafélag Íslendinga) - 01.06.1976, Side 129

Deuterium measurements have been made on water samples
collected from 17 hot springs in the area. For the location of the
sampling points see samples No. 1-17 in Fig. 32. Samples were
collected in the north-eastern part of the area at an altitude of ap-
proximately 700 m (samples No. 1-13), in the higher central parts
of the area at an altitude of approximately 900 m (samples No.
14-15) and on the southem slopes of the area at an altitude of
600 m (samples No. 16-17).
The chloride content of the water samples varies considerably.
The highest chloride content was found in the north-eastem part
of the area, up to 400 mg/1 Cl", indicating deep circulating water
which has acquired a considerable amount of Cl" by reaction with
rocks at high temperatures.
In other areas the chloride content was much less and the lowest
values, approximately 15 mg/1, were found in the hot springs on
the southem slope of the area. The temperature of the springs
varied from 11°C to the relevant boiling temperature.
In spite of different Cl“ content and water temperature, all the
hot springs have a similar 8D = — 76%0. According to the deu-
terium map, the same ðD-value is found in the Torfajökull area
itself hut it is also found in an area approximately 35 km to the
north-east. Since the latter-mentioned area has an altitude approxi-
mately the same as the lowest-lying springs, one would hardly
expect this area to be the recharge area for the geothermal water.
Therefore it is most probable that the geothermal water, both the
deep circulating water found in the north-eastern part of the area
and the low-chloride water found in the upper parts of the area,
originates in the Torfajökull area itself.
15. 3 Seljavellir.
On the southern slopes of the glacier Eyjafjallajökull there is a
single hot spring, Seljavellir, with a temperature of 65 °C. The deu-
terium concentration of the water is SD = — 65.5%0 (Fig. 32, sample
No. 18). According to the deuterium map the nearest precipitation
with the same deuterium concentration is found on the northem
slopes of Eyjafjallajökull and in the glacier Mýrdalsjökull.
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