Rit (Vísindafélag Íslendinga) - 01.06.1967, Qupperneq 142

138
Thus the main anomalies, A, BE, and Bw, seem unmis-
takably to correspond to the three recent volcanic zones of
Iceland. The correspondence seems to go even further; the
faint anomaly here termed aE might correspond to the
Pleistocene line of volcanoes marked hy Bjamarfell—Sand-
fell, and aw fits still more strikingly with the Pleistocene
volcanic line Mosfell-Sandfell—Hvalfell-Thverfell. If this is
the case, the faintness of the anomaly may be due to burial
under non-magnetic material from the activity on the A zone,
or it may be due to the increase in temperature due to such
coverage. On the other hand the high intensity of the A and
B zones would be due to the circumstances that the magnetic
bodies are recent.
The correspondence of the main magnetic anomalies to
the recent volcanic zones refutes the hypothesis (Pitman
et al. 1966) that the symmetric array of the anomalies is
caused by drift away from the central axis. According to
this hypothesis the B anomalies are about 8 millic-n years
old, whereas most likely they are of recent age.
The main jumps of all three lines, at a corresponding
place, does not only suggest yield in a general stress field,
but also simultaneity, at least in a geological sense. The re-
markable symmetry of the magnetic picture over the Beykja-
nes Ridge will most likely find a natural explanation on
the basis of wedges, such as is also suggested by the com-
mensurability of the width of the recent volcanic zones and
the thickness of the implied crust.
REFERENCES
Biilow, K. v., 1962: Entwurf einer tektonischen Skizze von Island. Geo-
logie, 11, 6—16. Berlin.
Einarsson, Trausti, 1950: The basic mechanism of volcanic eruptions and
the ultimate causes of volcanism. The Eruption of Hekla 1947-1948,
IV. 5, 30 pp. Vísindafélag Islendinga.
— 1963: Fjords and bays and old fractures in Iceland. Timarit V.F.l.
48, 33—39 (Icelandic with English Summary).