Jökull - 01.12.1992, Blaðsíða 35

Fig. 2a. Positions of profiles selected for paleomagnetic sampling and K-Ar dating west of Langidalur valley.
B: Bólstaðarhlíðarfjall, Æ: Æsustaðafjall, G: Gunnsteinsstaðafjall, H: Holtastaðafjall. The Blanda river and the
main road are also shown. — Staðsetning sniða sem sýnum var safnað úr austan Blöndu.
~ 40 m
Fig. 2b. View to the north showing three of our sampling profiles and six faults in the most steeply dipping
Part of the Langidalur lava pile. Adapted from Guðmundsson et al. (1982) with permission. — Teikning af
jarðlagahalía og misgengjum í Langadal.
to the Stakkfell central volcano, northeast of the study
area. The fiows of this formation can be traced over
long distances (Fig. 1) and tend to be thinner updip.
A formation of miscellaneous lava ffows rests on
t0P of the previous formation (profiles KM,KN,TM,
lower part of TN and base of TO). Within this forma-
t'on is a member of compound lava flows (in KN,TM
and TN). At the top of this formation are peculiar big-
felspar flow units (TO 5-7, TN 31) which can be traced
over vast distances towards southwest and northeast.
This flow seems to be composite, i.e. parts of it (espe-
cially towards northeast) are intermediate in composi-
tion and parts (towards southwest) are basaltic. This
flow is a good marker horizon. In the study area and
farther to the northeast it is often accompanied by a
rhyolitic lava flow (TN 32).
The uppermost formation (upper part of section
TN and TO and the whole of TP) comprises numerous
thin tholeiite flows, mainly aphyric but units of por-
phyritic flows are at the top (TP 70-7B). These flows
JÖKULL, No. 42, 1992 33