Jökull - 01.01.2010, Page 154

L. Kristjánsson
Figure 3. Stratigraphic sketch of profile WB in Þóris-
gil and Botnssúlur. Thol. = tholeiite, ol. = olivine
tholeiite. Altitudes (in meters above sea level) and
magnetic polarities (black = normal, white = reverse)
are on the left. – Skissa af jarðlögum í sniði WB og
segulstefnu þeirra.
PROFILES KJ, KI, KK, KP, KN, KO IN
AND AROUND STÓRA-SAUÐAFELL,
KJÓSARSKARÐ, SW-ICELAND
The so-called Kjósarskarð road (Highway 48) runs
south from the Hvalfjörður fjord, along the Laxá river.
Stóra-Sauðafell (Figures 1, 4 and 5) is a hill lying
about 1 km west of this highway and 5–6 km south
of one of Sigurgeirsson’s (1957) R3–N3 transition
sites, Kýrgil. The hill is just south of the map in
Figure 30 of Einarsson (1962). The author is not
aware of any previous published stratigraphic map-
ping in Stóra-Sauðafell or its vicinity. The main pro-
file KJ sampled in this project (Figure 6) begins above
a coarse-grained sediment. Exposures are not com-
plete and are separated by detritus-covered hillside in-
tervals of comparable vertical dimensions. The detri-
tus probably hides clastic sediments but these or the
flow boundaries are rarely seen; this accounts for the
difference in presentation of Figures 3 and 6. The ex-
posures KJ 16 consist of lava pods which appear to be
embedded in a thick clastic unit.
The mean directions of the KJ flows are listed in
Appendix 1, after correction for tectonic tilt which is
estimated to be 9◦ in a direction 130◦ east for all the
profiles of Figure 4. As in profile WB above, cluster-
ing of successive directions is seen in KJ 2–3, KJ 6–9,
and KJ 10A–15. KJ 10 with a mid-latitude VGP may
have been erupted at the beginning of the geomag-
netic polarity transition between emplacement of the
reverse zone KJ 1–10 and of the normal zone 10A–16.
The short profile KI 1–6 (to the right of the shal-
low gully in Figure 5) has more or less the same re-
manence directions as the flows KJ 1–6 although it
should be stratigraphically lower. This is probably
due to a fault located between them. A short profile
KK northwest of KJ was also sampled in an attempt to
reach lower levels in the lava pile. The two KK flows
indicate that the thickness of the reverse series could
be somewhat greater than the 80 m or so observed in
KJ. One assumes that this series is the R2 of Einarsson
(1962). The KK flows are unconformably overlain
by several flows of the interglacial "Reykjavík gray
basalt" lavas which also outcrop in the area between
the road and Laxá (Sæmundsson et al., 2010).
154 JÖKULL No. 60