Jökull - 01.12.1982, Page 105

Kristjánsson andMcDougall (1982). A recent paper by
Shaw et al. (1982) continues the Liverpool work on
this topic, but it may not take the effects of e.g.
secondary alteration sufficiently into account.
Schweitzer and Sojjel (1980) have published
paleointensity determinations from some post-
glacial lava flows. Einarsson (1976), Peirce and Clark
(1978), and Kristjánsson and Guðmundsson (1980)
studied occurrences cfvery young transitional and
reverse lavas in the volcanic zone.
RCXIK MAGNETISM
Several of the papers already mentioned contain
results of rock magnetic investigations. These in-
clude thermomagnetic curves, susceptibility re-
sults, storage tests for V.R.M. etc., mostly perform-
ed in connection with remanence measurements to
ascertain the carrier of the remanence and its
stability. Icelandic basalts are also represented in
some early general compilations of rock magnetic
properties in igneous rocks, e.g. that of Tarling
(1966) who points out that intensity and suscepti-
bility values in rock samples from various areas
follow approximately a lognormal frequency
distribution.
The Imperial College/Liverpool group was in the
early sixties studying the relationship between the
opaque mineralogy and magnetic properties of
igneous rocks. Using samples from various areas
including Iceland (collected by J. Hospers and T.
Sigurgeirsson) they made major advances towards
the understanding of magnetic stability, including
the development of a classification index for the
oxidation state of opaque iron-titanium minerals as
seen in polished section (Ade-Hall 1964, Wilson 1966,
Wilson and Haggerty 1967, and others). These papers
contain probably the first published electron micro-
probe analyses on Icelandic rocks. Later, the Liver-
pool group have published important papers on the
relation of oxidation state to magnetic stability and
other factors, both in their collection of lavas from
E-Iceland as a whole (Smith 1967b, Ade-Hall 1969,
Ade-Hall and Lawley 1970) and in single units
(Watkins and Haggerty 1965, 1968; Smith 1967c,
Wilsonetal. 1968).
The eílect ol low-temperature hydrothermal al-
teration upon the magnetic properties oflavas from
Iceland has also been studied in a major paper by
Ade-Hall et al. (1971) which demonstrates e. g. that
Gurie points in basalts rise during burial in the lava
pile. The efiect of alteration on remanence intensity
is discussed by Wood and Gibson (1976) and Watkins
and Walker (1977). Oxidation state ofopaques in an
E-Iceland dyke swarm was investigated by Birdand
Piper( 1980).
SEDIMENTS AND MISCELLANEOUS
After Hospers, thc only detailed study on magne-
tic properties in Iceland sediments is that oíGrijjiths
et al. (1960) who measured varved clay from Haga-
vatn. Measurements on remanence in baked sedi-
ments are reported briefiy by Doell (1972, Appen-
dix) and Smith (1967a,b). Sediments in the Tertiary
sequence have been sampled for magnetic measure-
ments by Soviet authors, but only their work on
Tjörnes sediments has yet been reported in papers
(see above). An Edinburgh University expedition
collected mud cores from a few lakes in Iceland for
magnetic measurements in 1979.
Measurements on the anisotropy ofsusceptibility
in Icelandic igneous rock units have been reported
by Ellwood andFisk (1977) and Ellwood (1978, 1979).
Some polarity measurements from Skagi, N-Ice-
land, arementioned by Evertsetal. (1972). Magnetic
measurements from Surtsey island are reported by
Sigurgeirsson (1974), Carmichael (1974), and Grommé
(in press 1982).
Some studies of the eflects of dyke intrusion upon
the magnetic properties of nearby country rock are
included in papers by Kristjánsson (1970), Doell
(1972) and Becker (1980).
MAGNETIZATION IN ANOMALY
INTERPRETATION
Magnetization intensity values have not becn
rcported in all paleomagnetic papers from Iceland,
but this aspect may be important in the interpreta-
tion of magnetic anomalies on a local or regional
scale. Several papers have been written to emphas-
ise intensity measurements.
'fhe first major effort in this field was made by a
groupfrom Munich University, who worked mostly
in the neovolcanic zone in NE-Iceland. It is review-
ed by Angenheisler et al.( 1977) and Becker (1980).
Other work includes that of Sigurgeirsson (1970),
Kristjansson (1970, 1972, 1976), Kristjansson and
Watkins (1977) and Pálmason at al. (1979). These
authors have made e. g. magnetic measurements on
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