Rit (Vísindafélag Íslendinga) - 01.06.1967, Side 101

MAGNETIC ANOMALIES
Gudmuiulur Gudmundsson*
Department of Natural Heat,
National Energy Authority, Reykjavík
ABSTRACT
The close fit between observed magnetic anomalies on the mid-ocean
ridges and theoretical profiles, based on the hypothesis of Vine and Matt-
hews and the times of reversals of the earth’s magnetic field, implies
that there is little mixing of basalts with a different polarity of the re-
manent magnetization. This imposes serious restrictions on the analogies
that can be drawn between Icelandic volcanism and the processes by
which the new oceanic crust is formed.
There are large linear magnetic anomalies striking N-S in Ljósa-
vatnsskard which is a deep passage through the mountains in the Ter-
tiary area west of the neovolcanic zone in N.-Iceland. Possible explana-
tions of the anomalies are discussed.
Magnetic Anomalies
1. Mid-Ocean Ridges
The linearity of mid-ocean ridges is most pronounced in
their magnetic anomalies. In 1963, Vine and Matthews sug-
gested that on the assumption of the spreading floor hypo-
thesis of Hess and Dietz (Hess 1962 and 1965, Dietz 1961)
and a reversing geomagnetic field, new material injected at
the centre of a mid-ocean ridge would over a time scale of
millions of years produce blocks of alternate normal and re-
* Now at Central Bank of Iceland, Economic Department, Reykjavík.
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