Greinar (Vísindafélag Íslendinga) - 01.01.1976, Blaðsíða 25

MARINE MAGNETIC SURVEYS OFF THE
WEST COAST OF ICELAND
LEÓ KRISTJANSSON
Science, Institute, University of Iceland.
Dunhaga 3, Reykjavik, Iceland
ABSTRACT
Marine ma.gnetic surveys were carried out at 10 kna line spacing on the West-
em Iceland insular shelf in 1972-3. After smoothing, correction for temporal
variations, and suhtraction of regional field, separate magnetic profile maps
have heen drawn for the Snaefellsnes-Breidifjördur and the Vestfirdir offshore
areas. The magnetic results confirm that sediments are thin on the shelf. Mag-
netic disturbances are considerably greater in the former area, due largely to
the presence of a number of localized anomaly regions in a belt running west
from the Snaefellsnes peninsula.
The localized anomaly regions, having dimensions of order 10 km each, are
most probably related to gahbroic rocks in central volcanoes; this is supported
by gravity evidence. Extended magnetic anomahes are not common and prob-
ably are due to SE-dipping lava series rather than dyke swarms or faults.
The concentration of central volcanoes, and lack of linear magnetic anomalies,
in the offshore area west of Snaefellsnes, indicate that it may have similarities
with the Iceland-Faeroe ridge.
1. ENTRODUCTION
A. The survey
In 1972 a committee, appointed by the Minister of Education,
initiated a programme of geophysical research on the shelf area
around Iceland. Bathymetric, gravity, sediment thickness (sparker)
and total-field magnetic field measurements were included. Posi-
tioning employed “Raydist” with a lane width of some 45 m. The
vessels used were the Coast Guard’s “Albert” in 1972 and the small
freighter “Isborg” in 1973.