Jökull - 01.12.1982, Page 84

Stratigraphic sections through drillholes
in Laugaland Eyjafjörður
Fig. 3. Stratigraphic section
through drillholes in the
Laugaland area. The section
crosses the section shown in
Figure 2 almost perpendicu-
larly. For explanation see
legend in Figure 2.
Mynd 3. Jarðlagasnið frá
norðvestri til suðausturs gegnum
borholur á Laugalandi. Sniðið er
nœr hornrétt á sniðið á mynd 2.
Laumontite is recorded First at 260-700 m
depth in the driliholes and in most drillholes
laumontite is the dominant zeolite below 400-
600 m depth.
Chabazite is found sparsely at the highest le-
vels in the drillholes. Thomsonite is found scatt-
ered down to about 1000 m depth. Apophyllite is
rarely found and only at shallow levels (above
300 m). Mordenite is found mostly at upper
levels in tholeiite lavas. Analcime is most comm-
on in the upper 500 m, but is found sparsely at all
depths. Stilbite is found mostly in fractures and
occurs at all depths in the driilholes.
Fleulandite is common and recorded at all
depths.
Epistilbite is found rarely. Similar trends are
found here for the distribution of zeolite species
in tholeiite and olivine tholeiite basalt as describ-
ed by IValker (1960). As the samples are all cutt-
ings this is not as distinct as found in the basalt
pile at surface. Gyrolite is found above 800 m
depth and occurs locally in great quantities.
Smectite is the dominant clay mineral replac-
ing the mafic minerals and finegrained matrix in
the basalts down to 1000-1500 m and is encount-
ered to the bottom of the drillholes. Smectite is
80 JÖKULL 32. ÁR