Greinar (Vísindafélag Íslendinga) - 01.01.1976, Side 99

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structures of a mid-ocean ridge otherwise covered by a thick layer
of water. A supposition appeared that Iceland is not a fragment of
the previous continent, but, on the contrary, a part of oceanic crust
which rose above sea level. This version was specially fortified after
the discovery (16) that the ocean bottom is composed mainly by
tholeiitic basalts, which were earlier considered as typically conti-
nental. Iceland is composed almost exclusively of basalts, similar
to the ocean bottom and dominated by tholeiitic basalts.
The usual structural peculiarity of mid-ocean ridges are longitu-
dinal grabens coinciding with the axial zone of the ridge. Grabens
are the major structural forms in Iceland also. This fact further
supported the conception about Iceland as a part of an ocean bot-
tom (39). In this connection a different interpretation was, natural-
ly, given to the origin of acid volcanic rocks of Iceland, the outcrops
of which cover up to 10% of the island’s area and which were earlier
considered as a sign of existence in the depths of remnants of con-
tinental crust. The researchers associated them with the differenta-
tion of the mantle material. The understanding of Iceland as ocean
bottom was supported also by geophysical data, which could be in-
terpreted as an indication of a thin crust (7, 18, 28, 20). The rare
opportunity for a walk on the sea bottom with the geological hamm-
er in hand could be also used for the direct study of the mechanism
of spreading apart of the “lithosphere plates”, postulated by the
“new global tectonics”.
All these possibilities have lately drawn to Iceland many scien-
tists from other countries. Soviet geologists, geophysicists and geo-
chemists, who worked in Iceland in 1970-1973, were also among
the foreign visitors. The peculiarity of the Soviet Geodynamics Ex-
pedition in Iceland was the large nrnnber of its members and the
complex character of researches: a group of specialists in different
branches of the geosciences worked in this Expetition coordinated
by a general program1. Of considerable importance were the cir-
1. Researches of the land part of the Expetition were carried out by V. V.
Beloussov (scientific leader), G. N. Akimov, M. A. Akhmetiev, A. R. Geptner,
V. A. Gerasimovsky, Yu. B. Gladenkov, A. V. Goriachev, N. A. Durasova, S.
M. Zverev, V. I. Kononov, A. A. Krasnov, N. A. Logachev, M. G. Lomize,
Ye. Ye. Milanovsky, B. G. Poliak, A. I. Poliakov, G. M. Solodovnikov, V. G.
Trifonov, A. N. Furtsev.
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