Náttúrufræðingurinn - 1981, Qupperneq 44

application to Iceland. Geophys. J.R.
Astron. Soc. 33:451—481.
— Stefán Arnórsson, Ingvar Birgir Friðleifsson,
Hrefna Kristmannsdóttir, Kristján Sæmunds-
son, Valgarður Stefánsson, Benedikt Stein-
grímsson, Jens Tómasson & Leó Knstjánsson.
1979. The Iceland Crust: Evidence írom
drillhole data on structure and processes.
Am. Geophys. Union, Ewing Series 2:
43—65.
Sigvaldason, Guðmundur E. 1963. Epidote and
related minerals in two deep geothermal
drillholes, Reykjavík and Hveragerði,
Iceland. U.S. Geol. Survey Prof. Paper
450—E: 77 — 79.
— 1964. Some geochemical and hydro-
thermal aspects of the 1961 Askja
eruption. Beitráge Min. Petr. 10: 264—
274.
Sæmundsson, Kristján. 1978. Fissure swarms
and central volcanoes of the neovolcanic
zones of Iceland. Geol. Journal Spec.
Issue 10: 415—432.
— & H. Noll. 1974. K/Ar ages of rocks from
Húsafell, Western Iceland, and the
development of the Húsafell central vol-
cano. Jökull. 24: 40—59.
— & Sigmundur Einarsson. 1980. Jarðfræði-
kort af íslandi, blað 3, SV-land, 2. útg.
Náttúrufræðistofnun Islands og Land-
mælingar Islands.
Thoroddsen, Þorvaldur. 1899. Jarðskjálftar á
Suðurlandi. Hið íslenzka bókmennta-
félag. Kaupmannahöfn.
— 1910. De varme kilder pá Island, deres
fysiskgeologiske forhold og geografiske
udbredelse. Kgl. danske Vidensk. Selsk.
forhandlinger 2:97 —153; 3: 183 — 257.
Tómasson, Jens, Ingvar Birgir Friðleifsson &
Valgarður Stefánsson. 1975. A hydrological
model for the flow of thermal water in
SW-Iceland with special reference to the
Reykir and Reykjavík thermal areas.
Proceedings 2nd U.N. Symposium on
the Development and Use of Geothernal
Resources. 1: 643 — 648.
Walker, G.P.L. 1959. Geology of the Reyðar-
fjörður area eastern Iceland. Quarterly J.
Geol. Soc. London. 114: 367 — 393.
— 1960. Zeolite zones and dike distribution
in relation to the structure of the basalts
of eastern Iceland. J. Geology. 68:
515—528.
— 1963. The Breiðdalur central volcano
eastern Iceland. Quarterly J. Geol. Soc.
London. 119: 29 — 63.
Þórarinsson, Sigurður. 1949. Um aldur Geysis.
Náttúrufræðingurinn, 19: 34—41.
Þorkelsson, Þorkell. 1940. On thermal activity
in Iceland and Geyser action. Visindafél.
ísl., Rit 25.
SUMMARY
Application of geology
in geothermal research
in Iceland
by Krislján Sæmundsson
and Ingvar Birgir Friðleifsson
National Energy Authority, Reykjavík
The basic principles of the origin and flow
pattern of geothermal waters in Iceland
were recognized by Bunsen (1847). More
detailed work carried out a century later
specified two main types of geothermal
activity in Iceland (Böðvarsson 1960, 1961)
(a) high temperature geothermal fields situated
within active volcanic systems and (b) low
temperature hot water springs distributed
all over Iceland outside the active volcanic
zones. The former develop above shallow
level intrusive complexes, mostly in the roots
of central volcanoes. The latter form under
conditions where water descends deep into
the bedrock, draws heat from it and ascends
along fractures and dykes driven by the
hydrostatic gradient (Fig. 1). Geological
mapping and petrographic studies help to
define many important parameters which
control the flow of groundwater, such as
rock type, compaction, alteration and
vesicle filling, strike and dip of the lava pile
and the trace and attitute of faults, fractures
and dykes cutting it. Of main concern is to
define the nature of the aquifers and
whether they are localized steep fractures or
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