Jökull - 01.01.2005, Blaðsíða 21

Stratigraphy and paleomagnetism of Suðurdalur, Eastern Iceland
Figure 2. Three cross-sections through the Norðurdalur and Suðurdalur valleys and the intervening Múli ridge,
looking north. The positions of lava suites HF through SA (see text and Figure 7) in these sections are shown,
as well as regional alteration zones and faults. Our profiles ST, MK in Suðurdalur and profile S of Watkins and
Walker (1977) in Norðurdalur lie close to the middle section. – Þverskurðir landslags, jarðlagasyrpa, höggunar
og ummyndunar gegnum Suðurdal, Múla og Norðurdal.
the basalt, intermediate and acidic rocks occur at 3–4
different stratigraphic locations in the lava pile. The
intermediate rocks are basalt-andesite or dacite, and
the acidic rock is rhyolite.
The sediments in the area occur mainly as rela-
tively thin interbeds (<0.5 m) between lava flows, or
as thick accumulations (5–100m ormore). In the low-
est part of the pile most sediments are fine-grained and
tuffaceous, but as we go higher in the stratigraphy the
sediments are increasingly coarse-grained, i.e. sand-
stone, conglomerates and diamictites. This probably
reflects gradually cooler periods with subsequently in-
creasing glaciations.
Lithostratigraphic units (suites)
The lava pile of the Fljótsdalur area has been di-
vided into fourteen lithostratigraphic suites (series).
They are briefly described below, with the exception
of three young localized ones at the top. Figure 2 il-
lustrates the position of most of these suites in three
cross-sections through Suðurdalur, Múli and Norður-
dalur. As regards discussion of the age of the suites,
this is based on tracing them over to the composite
section described by Watkins and Walker (1977) on
the north side of Norðurdalur-Fljótsdalur.
VV-suite (Víðivallasyrpa), named after the Víði-
vallaháls ridge at the eastern side of Fljótsdalur (Fig-
ure 1). Above the Víðivellir farms some 250 m thick
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