Jökull - 01.01.2016, Page 90

Leó Kristjánsson
Figure 4. A very simplified scheme of outcrops
sampled by Kristjánsson (2015) and of those added
in the present paper (profile names underlined).
Lines indicate some of the definite correlations be-
tween individual sites which are based on lithol-
ogy and the apparent dip but primarily on a coinci-
dence of remanence directions (Table 2). Approx-
imate distances between the profiles are indicated.
– Mjög einfölduð mynd af opnum sem safnað var
kjarnasýnum úr 2012–2014 og 2014–2016, sumum
tengingum milli þeirra, og fjarlægðum.
The large black dots in Figure 5 denote VGP po-
sitions from flows DV 9, DW 4, 9, DQ 1, 3 and DI
4 which clearly lie more than 10◦ away from any of
the poles making up the red composite pole path from
Kristjánsson’s (2015) profiles. The smaller black dots
similarly represent poles from flows DE 5, 8, 10, 16
and DF 9, 11, 12 in the profiles of Kristjánsson and
Jóhannesson (1996). They are selected for insertion
here to emphasize that the movement of the virtual
pole during this excursion must be truly complex. Its
wanderings do not seem to be confined to any pre-
ferred intervals in longitude or latitude.
These results show that exposures belonging to
the Kleifakot geomagnetic event reach for at least 5–
6 kilometers along strike on both sides of Ísafjörður,
measured from profile DF on the southeast side and
DV on the northwest side.
The new profiles and some of the correlations
between them are shown schematically in Figure 4.
Table 2 is a list of pairs of remanence directions
employed for correlation purposes by Kristjánsson
and Jóhannesson (1996), Kristjánsson (2015) and the
present study.
ON THE INTENSITY OF THE
PALEOMAGNETIC FIELD
Estimates of the absolute intensity of the geomagnetic
field during emplacement of igneous bodies are of sci-
entific value regarding its long-term characteristics,
especially during transitions and excursions when it
is relatively weak (Kristjánsson 2013, Fig. 7). One
might expect that such measurements in situations
like the Kleifakot geomagnetic event could yield in-
teresting results about the field when in an unstable
state.
From our demagnetization results and other evi-
dence on the lavas from the Kleifakot event in Ísa-
fjarðardjúp (Kristjánsson, 2015, p. 315), they are
however unlikely to pass suitability tests for paleoin-
tensity studies. In several of the excursion outcrops
at higher altitude in profile JD (Figure 2a), the VRM
component in some samples is however small and
can be removed by AF treatment at 10 mT or less
with minimal effect on the TRM. They might possi-
bly provide some satisfactory paleointensity results, if
supported by consistency between samples collected
from widely spaced sites in a unit as well as between
90 JÖKULL No. 66, 2016