Jökull - 01.12.1982, Page 102

Fig. 5. R. L. YVilson and J. Edwards coring lava
no. 5 in profile EQ, Bessastaðaá, summer of 1965.
Photo L. Kr.
Mynd 5. Sýnasöfnun á Fljótsdal sumarið 1965.
Liverpool (were VVilson was setting up a labora-
tory), N. D. Watkins (a former associate of Doell),
P. Smith and S. E. Haggerty (graduate studcnts).
Sampling (two per fiow) was partly by hand sampl-
es in the SVV, but in E-Iceland all samplcs were
collected by means of portable drills provided by
VVatkins. The 1965 collection, covering Fljótsdalur
and a couple of profiles in Alftafjörður, was mostly
made by VVilson and J. Edwards (Fig. 5). In 1967,
P. Dagley and assistants carried out detailed collec-
tion at some magnetic polarity transition zones in
E-Iceland.
The total number of flows sampled was ca. 300 in
SVV-Iceland, and 1 100 in E-Iceland (including 200
thin extra flow units). This was by far a world
record at the time. Specimens from all cores were
measured in detail in Liverpool, and the remanence
ofduplicatespecimensfrom many ofthese lavas was
measured in an astaticmeter in Reykjavík.
The SVV-Iceland profiles did not constitute a
complete stratigraphic section, and detailed re-
ntanence results from these have not been publish-
ed. IVilson et al. (1972) presented polarity diagrams
and plots for the individual profiles, including pol-
arity zone numbers according to Einarsson’s
scheme, but few correlations were indicated. In-
dependently, however, J. D. A. Piper of Imperial
College (Iater of Liverpool University) carried out
field mapping in the Hvalfjördur-Borgarfjördur
area and made the first detailed correlation ofgeo-
magnetic polarity zones in SVV-Iceland with the
named epochs ofthe polarity time scale (Piper 1971,
1973b). Although various aspects of this correlation
and of his associated conclusions on crustal growth
in Iceland have now been revised (see below), Pip-
er’s work served as a useful basis for discussions of
the geology of SVV-Iceland forseveral years.
Initial paleomagnetic results from E-Iceland
were published by Dagley et al. (1967). Radiometric
dataon cores, althoughpoor, indicated amaximum
age of 20 M. y. Dagley et al. estimated that 60
reversais occurred in their complete profile, though
correlations between some of their 21 sections were
uncertain due to the long distances involved. This
result was in good agreement with reversal rates
that were being deduced from ocean floor magnetic
lineations in 1966-67, and Dagley et al. attempted
some correlations with these time scales. They also
estimated volcanic production rates and revised
IVensink’s (1964) polarity schemefor Fljótsdalur.
Details of the E-Iceland work were published in a
large paper by Watkins and Walker (1977). These
included paleomagnetic data for all flows and flow
units, stratigraphic profiles with correlations, stads-
tical treatment of remanence directions, and much
other information. It should be noted that Watkins
and Walker (1977) use a much less stringent rejection
criterion for internally discordant flows than most
other paleomagnetic workers, and this criterion has
even not been applied consistently in constructing
polarity columns in their Appendix.
The main other publications on paleomagnetic
work from the E-Iceland fjords are that oi'McDoug-
all et al. (1976a) which correlates a Iong normal-
polarity zone in Dagleyet al’s (1967) profilcs E, F and
J with polarity epoch 9, and work by Piper et al.
(1977) on 40 lavas and 103 dykes in the Reyðar-
fjörður area. Magnetic measurements on large
nuntbers of Reyðarljörður rock units are in the press
98 JÖKULL 32. ÁR