Rozwój poglądów na zagadnienie teorii tektoniki płyt

Abstract

THE CURRENT VIEWS ON THE THEORY OF PLATE TECTONICS Summary Current trends in the development of the theory of new plate tectonics are discussed in connection with the previous paper (W. Pożaryski - New pIate tectonies, Prz. geol., 1971, no. 8-9 and 10). At present, partly under the influence of adversaries, intensive studies of geochemical and physical aspects of the theory can be observed. Remarkable attention has been paid to the J . T. Wilson's (1963, 1973) hypothesis of hot spots, which assumes stability of source of heat in astenosphere. The rise of interest in this hypothesis resulted from the fact that it seemed to provide additional criterion for evaluating plate motions and to explain the process of breaking up of continental blocks. However, newer data appear inconsistent with this hypothesis. Moreover, further attempts to determine the driving force of plate motion are under way. The second front of studies, apparently more important nowadays, comprises studies of continents. The plate tectonics theory assumes that old ocean crust undergoes subduction into the mantle and assimilation. No ocean crust older than Mid Jurassic is known at present, hence studies of plate motions in pre-Mid Jurassic . times cannot be carried out on the way of analysis of oceanic crust but rather by analysis of results of assumed motions of plates. The results of the motions include displacements and deformations of continental blocks dredged by oceanic plates. The most spectacular deformations include orogenic belts related to plate collisions; however, their reinterpretation in terms of the plate tectonics appears highly difficult as it requires redefinition of several basic concepts such as geosyncline, orogen, craton, and others. Moreover, the reinterpretation requires far more precise knowledge of paleogeography than it is available at present.