Jökull - 01.12.1982, Side 104

Fig. 6. Sections sampled for
paleomagnetic and K-Ar work
by N.D. Watkins and collabor-
ators, 1972-1978.
Mynd 6. Sýmtökusnið N.D. Watk-
ins og samstarfsmanm.
Súgandafjördur area in 1966-67 for laboratory
magnetic measurements. Until K-Ar dates appear-
ed in 1967-68, these oldest lavas in NW-Iceland
were still thought by many to be possibly Eocene
and to have been deeply buried. Kristjánsson’s
mean field direction corresponded to a magnetic
pole at 83°N, 155°E; previous published pole posi-
tions from Iceland had been based partly on unde-
magnetized samples (Hospers 1953b, Wensink 1964)
and partly on much smaller collections of single
samples (Sigurgeirsson 1957, Smith 1967a). This re-
sult indicated little net apparent polar wandering
(<8°) during the buildup of the lava pile, and sub-
sequent work has further reduced this estimate.
Kristjánsson et al. (1975) provided detailed re-
manence results from a profile of 44 lava flows south
of Arnarfjörður, and suggested a stratigraphic cor-
relation between this area and that of Friedrich
(1966).
A substantial sampling effort (1261 lavas) was
carried out on a section through NW-Iceland in
1975-77 by the late N. D. Watkins and others (in
press 1982), cf. Fig. 6.
PALEOINTENSITY, TILXNSITIONS, ETC.
P. Smith sampled a number of baked sediments
underlying Cenozoic Icelandic lavas during the
1964 expedition referred to above. These and
deuterically oxidized lava samples were found to be
good material for studying the intensity of the
paleomagnetic field. Results were published by
Smith (1967a); additional experimental details are
given by Smith (1967b) and Wilson andSmith (1968).
These Icelandic data provided useful information
on the geomagnetic field strength; according to
Smith’s review this field appears to have been on
average somewhat weaker in the Tertiary than at
present.
Lawley (1970) and Dagley and Lawley (1974) studi-
ed six transitions in E-Iceland resampled in 1967,
and some transitions from SW-Iceland previously
reported by Wilson et al. (1972). No preferred pole
path emerged in these or other similar studies re-
viewed by Dagley and Lawley. Shaw (1975; Shawand
Wilson 1977) sampled the R3/N3 geomagnetic
transition in detail at six separate localities in Esja
and Hvalljördur, assuming a certain time sequence
for the lavas sampled at these sites. He found that
most but not all of the lavas yielding low-latitude
poles also have relatively weak virtual dipole mom-
ents.
Dagley and Wilson (1971) and Wilson et al. (1972)
carried out a quantitative analysis ofrelative Upper
Tertiary geomagnetic dipole moment strengths by
grouping intensity data from cores of the SW-and
E-Iceland collections. They also pointed out that
normally magnetized lavas are more common than
reverse lavas in these collections. Some of the con-
clusions in these papers have been discussed by
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