Rozważania nad istotą i nazewnictwem platform

Abstract

CONSIDERATIONS ON ESSENCE AND NOMENCLATURE OF PLATFORMSSummaryThe tectonotype of continental platforms is represented by the East-European platform. The evolution of the notion of platform was substantiated by E. Suess (1881-1009), A. P. Karpiński (1894-1919) and E. Haug (1907). The further development of the research on platforms was due to L. Kober(1921), S. v. Bubnoff (1923), H. Stille (1924), D. Sobolev (1926). The ultimate definition of the East-European p1atform we owe to A. P. Karpiński (1919) and A. D. Archangielski (1932, 1940, 1941). The best services in the recognition of the tectonics of the East-European p1atform were rendered by A. D. Archangielski (1923, l933, 1940, 1941) and N. S. Shatski (1940, 1946, 1948, 1952). Studies on platforms in Poland were begun in the fifties during the attempt at making the tectonic synthesis of the area of Poland. Among the more important works in this domain are those of W. Pożaryski, J. Oberc, S. Sokołowski, J. Znosko, H. Tomczyk (see page of the Polish text).The author reviews the characteristic and diagnostic features of platforms, gives their definition, characterizes the basement of platforms and their sedimentary cover, discusses also nomenclature of platforms. Moreover, the author takes into consideration the creation of the names of platforms according to the accepted principle, i.e. either according to the time of geosyncline inversion, or to the time of formation of sedimentary cover. In consequence of this, an apparent contrast comes to light of such names as Caledonian platform and Epi-Caledonian platform (similarly as Variscan platform and Epi-Variscan platform).In the first case, precise and synonymous definition concerns the platform basement only, whereas in the second case - platform sedimentary cover. It appears that both logical and lingual requirements may be satisfied by the nomenclature that takes into account two main elements of the platform, i.e. basement and cover. Hence, the proposed nomenclature: Post-Karelian platform, Post-Baltikal platform, Post-Caledonian platform and Post-Variscan platform. The prefix "post" may be used with tectonic notion, but it cannot be linked up with stratigraphical notion. This means that we may discuss the Palaeozoic platform, but we cannot say about Post-Palaeozoic platform, since the contents of both names are in this case different.Two platforms are found in the area of Po1and: Pre-Cambrian platform and Palaeozoic platform. Except for the Carpathians, the Sudetes and the Świętokrzyskie Mountins, they comprise the whole area of Poland.As far as the Palaeozoic platform is concerned, both the part of basement characterized by Caledonian consolidation and the part of basement characterized by Variscan consolidation have so far not been distinguished more in detail.It should be expected that in the forefield area and in the surroundings of the Sudetes the basement of Variscan consolidation exists, and consequently also the Post-Variscan platform.According to the results of the research made in the last 10 years, the ,Świętokrzyskie Mountains should be considered to be an area of Caledonian consolidation. In the light of the detailed tectonic-structural studies carried on at present, the opinion on their Variscan origin cannot be confirmed. The Variscan and the Alpine tectonics in the Świętokrzyskie Mountains is posthumous, superposed. The younger Palaeozoic formations in the Świętokrzyskie Mountains are, in their development, typical of the so-called young platforms (labile shelves), and the tectonics is typically disjunctive, with all its derivatives (box folds, horst-like style of mountains). Round the Świętokrzyskie Mountains, the basement under the sedimentary cover may be of Caledonian consolidation.The extents of the Variscan and Caledonian basements in the Polish Lowland area have not so far been explained, thereby the boundary between the Post-Caledonian and Post-Variscan platforms has not been elucidated.