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Physical Geography of Northern Eurasia

Tectonics and Geology

| Physical Geography Index | The Relief of Northern Eurasia >>>

Introduction

Northern Eurasia, within the limits of the territory of the former Soviet Union (FSU), has an immensely long and intriguing history, and most of it consists of very ancient blocks that are cemented by fold belts into a single continent. The most important of these continental blocks, because of their sheer size, are the East European and Siberian platforms.

These platforms have shown dramatic movements through geological time. Indeed, although they both existed 1700 million years ago, in the early Cambrian (c. 540 million years ago) Eastern Europe and Siberia were both located in the Southern Hemisphere. The former platform was in a temperate climatic zone and the latter in the tropics! They were separated from each other, and from the other continents, by wide oceans. The subsequent closure of oceans and numerous continental collisions account for the predominantly accretionary tectonics of the area and for the wide distribution of fold belts like the Urals.

Present plate margins occur mainly on the margins of the territory of the FSU. In the far east, the Pacific Plate is being subducted under Eurasia at a rate of 10 cm per year. It is here that one finds the Kuril-Kamchatka island arc with its active volcanism. In the far north, under the Arctic Ocean, the Gakkel (Arctic Mid-Ocean) Ridge marks both the boundary between the Eurasian and North American Plates and the spreading axis along which the Eurasian ocean basin floor is forming. In the south the two great platforms are bordered by the African-Arabian, Indian, Tarim, and North Chinese continental blocks, and it is here that the highest mountains, recent volcanic activity and currently intense seismic activity are concentrated. Great mountain chains, like the Caucasus and the Pamirs, have been created by the continental collision of broken fragments of Gondwanaland with the mass of Eurasia. This remarkable history of plate interactions, which is fundamental for an understanding of the gross relief of Northern Eurasia is described by Zonenshain et al. (1990a, b).

| Physical Geography Index | The Relief of Northern Eurasia >>>

 

 


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