Rit (Vísindafélag Íslendinga) - 01.06.1976, Blaðsíða 170

understood if we use the same flow model for Húsavík as for Vest-
mannaeyjar. The water from the deeper aquifers would then origi-
nate farther inland and contain less deuterium than in the upper-
most aquifers. The water from the 50 m deep well H-2 has 8D —
— 72.6%0, which is the same deuterium content as in the precipita-
tion around Húsavík. Water from the 320 m deep well H-3 has
ðD = — 79.6%0, which is similar to precipitation approximately 20
km south of Húsavík. Water from the deepest well, H—1 (1506 m
deep), contains less deuterium, ðD = — 130%o, than any average
precipitation found in Iceland at present.
Increasing Cl’ content with depth indicates that the water in the
deepest aquifers has acquired a larger amount of Cl_ from the rocks
than the uppermost aquifers or that the water has mixed directly
v\dth ocean water. An aquisition of Cl~ is not difficult to explain if
the deeper aquifers have passed through more solid material, which
in some cases consists of chloride-rich sediments. Increasing tem-
perature also affects reactions which release chloride into solution.
According to Tahle 14, the relationship between Cl_ and deu-
terium in the Húsavík wells is almost linear, where higher Cl_ con-
tent means lower deuterium content. This may raise the question
whether the deuterium content of the water has been affected at the
same time as the water has aquired its Cl_. The results obtained for
Hafralækur, where an exceptionally low ðD-value is associated with
very low Cl_ content, however, contradict this. Hafralækur, located
approximately 20 km south of Húsavík, has the lowest ðD-value
found in Iceland to day, ðD = — 142.6%0, but contains only 10
mg/1 of Cl-.
As previously discussed, several other observations also contradict
this. Clayton et al. (1966) found no relation between deuterium
and Cl_ content in the brines of the Michigan, Illinois, Alberta and
Gulf Coast basins although the brines contained dissolved salt up
to 16 times that of sea water. The previously discussed wells in
Akranes, Leirá and Brautartunga, which are thought to be derived
from the same deep water flow, all have similar ðD-values in spite
of the fact that the Cl- content in these wells varies greatly. On the
other hand, the two water types in the Vestmannaeyjar well are
quite different in 8D-value although the Cl- content is practically
the same. Finally, in the four cases where both 8D and 8018 have
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