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The “Tectonic Map of the Polar Regions of the Earth” has been compiled on the scale 1:10,000,000, and structural regions have been distinguished on the basis of genesis and age. The map is accompanied by sketches of geotectonic zonation, neotectonic data, and geophysical characteristics reflecting deep features of the Arctic and Antarctic regions.

The North and South Polar regions have had different histories since Proterozoic time, and their deep-seated structures differ. The Arctic and Antarctic, although both are regions where the Pacific and Atlantic structural segments join, did not have similar géosynclinal and tectono-magmatic development.

In the Arctic, the stable Precambrian platform underwent fragmentation which gave rise to smaller platforms and central stable regions fringed by fold systems such as the Baykalides, Caledonides, Hercynides, and Mesozoides. The asymmetrical structure of the Arctic is evidenced by the differing degrees of stability of its western and eastern segments. The Antarctic, in contrast to the North Polar region, represents a heterogeneous pre-Riphean platform of a Gondwana type similar to the platforms of Africa, South America, Australia, and India. In West Antarctica the platform is fringed by the Antarctandes, which belong to the Pacific mobile belt. The Archean and Proterozoic mag-matic complexes of the two Polar regions are almost the same type. The Antarctic is characterized by a widely developed charnockite formation.

The earth's crust in the Arctic is of complex structure and greatly varied thickness. In the Arctic basin, three areas may be distinguished: “normal ocean,” transoceanic ridge area (Lomonosov and Mendeleyev-Alpha ridges), and the Canada basin. The Antarctic continent has mainly continental crust, but subcontinental crust is present at the West-East Antarctica juncture. The South Ocean is underlain by oceanic crust with some complications within the submarine ridges.

It is postulated that the thickness and crustal structure have changed abruptly in the Arctic during geologic history but were more stable in the Antarctic. The youngest tectonic event is marked by reactivation of structural features which determine the modern relief forms. Block movements are significant in the Antarctic. Besides these movements of opposite sense, a concentric distribution of the main structural features about the geographic poles is apparent in the polar regions.

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