Jökull - 01.12.1992, Blaðsíða 41

TN
---- 85
8.2 m.y. {
a few degrees of arc. The directions hence have to be
used with some caution. Virtual geomagnetic poles
(VGPs) have been calculated for each lava, using the
mean site coordinates 65.55° N, 19.9° W.
Paleomagnetic polarities for each sampled lava are
shown in Figs. 3-5 along with other information. The
VGP latitude has been plotted as a function of strati-
graphic height in Fig. 7 for a composite section con-
sisting of flows TL 1-33, KL 13-17, KM 1-5, KN
1-23 and TN 0-85. Here, overlaps have been ex-
cluded: note that all of profile TM overlaps with TN
and KN. The agreement between polarities and even
tndividual directions in overlapping profile segments
ls good, see for example the low-latitude poles at the
toP ofKL and TL (Table 1). The composite profile has
a total thickness of 1150 m and includes 139 sampled
Fig. 8. Composite strati-
graphic diagram of profiles
TL through TN, showing pa-
leomagnetic polarities and
mean ages. Reverse polar-
ity is white. Arrows indi-
cate extent of sampling for
laboratory magnetic mea-
surements, with two seg-
ments (broken arrows) omit-
100 m ted here. Stars indicate K-Ar
dated flows. —Segulpólun
og meðaltöl aldursgreininga
í samsetta sniðinu.
flows which have «95 values less than 60°. Note that
in Fig. 6 the total thickness appears to be only 1000 m
but this is due to a different arrangement of individual
proíiles in the composite section.
The mean paleomagnetic direction from those 134
lavas in the composite section which have an a95-value
of 23.5°or less, has a declination D = 4°, inclination
I = 74.2° with a vector sum R of 124.6 which corre-
sponds to a circular standard deviation (c.s.d., uncor-
rected for within-site scatter) of 21.7°. The mean of
the VGPs from the same collection is at a longitude of
112° E, latitude 86.3°N (a95=5°), which is quite close
to the geographic pole indicating that the tilt correc-
tion which we have used is reasonable. It is slightly
"right-handed" as has been found for some other mean
poles from Icelandic lavas (Kristjánsson and Jóhann-
JÖKULL, No. 42, 1992 39