Jökull - 01.01.2004, Page 59

Paleomagnetic directions in the Tjörnes beds, Northern Iceland
SAHM
KG
HK
HV
12´
8´
4´
66°
17° 12´W
Hallbjarnarstaðaá
Skeifá
Br.
9°
Flatey
Figure 1. The five sampling lo-
calities in Tjörnes. Places men-
tioned in the text include the
Breiðavík inlet (Br.), as well as
Kambsgjá, Hallbjarnarstaðakambur
and Höskuldsvík which are are
small geographical features coin-
ciding approximately with the sites
KG, HK and HV respectively.
– Borstaðir í Tjörnes-setlögunum.
less well defined than on basalt cores, reducing the
accuracy of laboratory measurements. Many cores
broke during orientation and transport, but most could
be glued together. All were coated in clear varnish be-
fore slicing. One specimen was measured from each
sample.
Measurements and data processing
Remanence measurements were made on the natural
remanence (NRM), and after AF demagnetization at
10, 15 and 20 mT peak fields with a Molspin demag-
netizer. The remanence is much weaker and usually
less stable than in typical lavas, the low stability being
exhibited either as a directional trend with increasing
peak field or as erratic variations at 20 mT. The lat-
ter variations were most noticeable in the component
along the core direction in each case, reaching up to
tens of degrees. The spurious variations appeared in
some cases to be due to RRM; similar variations have
also been seen in recent work on Miocene sediments
from Northwest Iceland (Kristjansson et al., 2003). It
should be noted that our demagnetizer has a higher
field frequency (172 vs. 69 Hz) and tumbling speed
than that used on sediments by Eiríksson et al. (1990).
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