Jökull - 01.12.1986, Síða 15

tants and on the westem part of the peninsula some
additional 14,000 are living in urban settlements,
exclusive the Keflavík air base with a population near
to 6,000. Those 150,000 (60 % of the total in Iceland)
are supplied with fresh water from the Reykjanes pen-
msula and its eastward prolongation (fig.2).
The Suðurnes Regional Heating also uses fresh-
water for its thermal plant at Svartsengi, as the ex-
tracted thermal water is saline (% sea water) and not
suitable for direct use. In the last years some fishfarms
have been established in this area, eventually needing
great quantities of water. There seems to be a rapid
increase in demand for freshwater from the Reykjanes
peninsula, yet at present no thorough survey on fresh
water and hydrogeology has been made covering the
whole area in question.
The geology of the postglacial volcanism has been
mapped in detail (Jónsson 1978). The explanations to
the maps include the most detailed information avail-
able on the older rocks as well. The Municipal Water
Works of Reykjavík have had many investigations
carried out on their extraction area, but few of the
results have been published. A preliminary study was
made of the Straumsvík area some years ago (Sigurðs-
son 1976) at the request of the Icelandic Aluminium
Company. An intensive survey of the western part of
the peninsula has been made on behalf of Suðurnes
Regional Heating (Þórarinsson et al. 1976; Sigurðsson
1978; Sigurðsson et al. 1978, Ingimarsson & Kjaran
1978; Ingimarsson & Elíasson 1980; Sigurðsson
1985). On the densely settled Rosmhvalanes penin-
sula only sporadic investigations have been made on
the freshwater and the obtained data is not very
coherent. The present article is a short summary of
the research that has been carried out on the Reykja-
nes peninsula in the last ten years but with an
emphasis on the authors own work.
GENERAL DESCRIPTION
The Reykjanes peninsula is a product of the
Reykjanes Volcanic Zone, which connects the Reykja-
nes Ridge with the volcanic zones of southern Iceland
(fig. 1). It is thus a part of the global oceanic rift sys-
tem of the Mid Atlantic Ridge, or at least in some
connection with it (Kristjánsson 1980). The volcanic
rocks are of basaltic composition ranging from some
few occurences of small picrite lava shields through
olivine- tholeiitic shield volcanoes to tholeiitic lavas
from eruptive fissures (Jakobsson et al. 1978) (fig. 3).
The interglacial rocks and those from the Postglacial
form extensive lava fields. The lavas have flowed out
from the mountainous active volcanic zone, forming
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2|iilD 6 O 7 f.
8 / 9 •
Fig. 3. Geology of the Reykjanes
peninsula. The rocks are volcanic
and consist of basalt lavas and sub-
glacially formed hyaloclastites (Sig-
urðsson 1985). Mynd 3. Jarðgerð
Reykjanesskaga. Á skaganum skipt-
ast á basalthraun frá nútíma og hlý-
skeiðum og móbergsfjöll frá jökul-
skeiðum (Freysteinn Sigurðsson
1985).
Explanations/Skýringar.
1 ■ Early Quatemary rocks / Árkvartert berg.
2. Interglacial basaíts / Grágrýti.
3. Lavacaps / Basalthettur.
4. Hyaloclastites / móberg.
5. Boundaries of fissure zones / mörk sprungusvœða.
6. Interglacial lava shields / Grágrýtisdyngja.
7. Recent lava shield / Dyngja frá nútíma.
8. Eruptive fissures / Gossprungur.
9. Single craters / stakar gosstöðvar.
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