Greinar (Vísindafélag Íslendinga) - 01.01.1976, Blaðsíða 116

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Part of the data used by Sheinmarm, is now out of date. Some
of his arguments are based on the composition of hasalts, that now
the oceanic rocks are better known, seem to be less convincing. But
it is quite surprising how the new more reliable geological and
geophysical data about the structure and history of development
of Iceland confirm the hasic idea of Yu. M. Sheinmann. And really,
the most probable interpretation of the whole complex of known
facts results in the same succession: continental crust — effusion of
plateau-basalts-transformation of the crust and its subsidence —
formation of rift. Only the degree of the crust’s transformation
tumed out to be considerably less than previously supposed hy
Sheinmann. He proceeded from the data about a thin cmst, while
now a large thickness of the crast is established and its transforma-
tion just beneath Iceland led until now not so much to the reduc-
tion of thickness as to the increase of its average density as the
result, as we might think, of the intrusion of mantle material into
it. Anyway, a thinner cmst under Iceland-Faroes threshold reflects,
apparently, the following stages of transformation of continental
crast into oceanic. As regards the rift structures of the mid-ocean
ridge, they become “superimposed” on the initial continental struc-
tare of Iceland.
It is known, that the modem ideas of “ocean floor spreading”
and continental drift postulate the “opening” of the Atlantic ocean,
including its northern part.
We should firmly state, that on the latitude of Iceland such pro-
cess is absolutely impossible, because till the end of the Paleogene
the entire Northem Atlantic was dammed across by land, which
included within its limits hesides Iceland itself the Iceland plateau,
the Rockall plateau, the Iceland-Faroes threshold. There is hardly
any doubt that the Iceland-Greenland threshold should also he in-
cluded; it is still scarcely studied but has obviously the same nature
as the Iceland-Faroes threshold. A solid neck of land is thus formed
completely “fixing” the continents on both sides of Northem
Atlantic in their places and excluding the possibility of their ever
joining with each other. Spreading is possible only within the rift
zones themselves, but we have seen, that rifting on that scale is
nothing as compared with that needed by the hypothesis.
What is the relation, then, of this latitudinal and stretching across