Jökull - 01.12.1992, Side 39

-1000
-900
- 200
-100
TP
Fig. 6. Composite strati-
graphic diagram of profiles
TL through TP, simplified
from Figs. 3-5. Lava types
and their suggested sources
are shown. —Helstu berg-
gerðir og tengingar í sam-
settum jarðlagastafla í Lang-
adal.
belong to two contemporaneous central volcanoes, i.e.
the Vatnsdalur central volcano to the southwest and the
Skagi volcano towards the north (Fig. 1). It is likely
that this formation rests unconformably on the previ-
ous one.
Hydrothermal alteration. The regional basalt suc-
cession has been affected by burial metamorphism
°f the type described by Walker (1960). The lower
Parts of profiles TL, TM and KN are in the mesolite-
s;colecite zone of alteration but the other profiles are in
the analcime and chabazite-thomsonite zones.
Tectonics. This aspect of the geology of Langi-
dalur will not be dealt with here. However, we wish to
draw attention to the extensive observations of Guðm-
undsson et al. (1982) on tectonics in Blöndudalur and
Langidalur by reproducing a diagram (Fig. 2b) from
their report.
PALEOM AGNETIS M
Paleomagnetic sampling and methods. Samples
for paleomagnetic measurements were collected us-
ing portable gasoline-powered drills (cf. McDougall
et al. 1984). Usually three 2.5 cm diameter samples
JÖKULL,No. 42, 1992 37