Rozwój poglądów na tektonikę obszaru Polski

Abstract

Development of ideas concerning the tectonics of Poland The principles providing the rational foundation of interpretation of tectonic features and forming the base of tectonic division of the lithosphere were formulated in late 19-the and early 20-th century. The principal ideas were set forth by M. Bertrand (1887), E. Suess (1909), and E. Haug (1907), who established the tectonic regionalization on the basis of the age of folding of large areas of the Earth. Thus, the process of inversion of tectonic development, in which a géosynclinal area is transformed first into a folded mountain belt, and then after peneplenation and deposition of epicontinental marine deposits into a platform — became the principal criterion of tectonic divisions. H. Stille (1920, 1924) established subsequently, that within the Mediterranean geosyncline small consolidated massifs of much older folding and metamorphism occur in folded zones of various age. He proposed therefore, to base the tectonic divisions not on the principle of age of folding, ibut rather on the age of tectonic consolidation of an area. Tectonic research carried out in Poland in the past century was conducted in a traditional way. Results of structural analysis presented on geological cross-sections were supplementing the geological maps. These studies were carried out by L. Zejszner, W. Teisseyre and the large group of authors of the Geological Atlas of Galicia. A major change of view in tectonics occurred at the beginning of the 20-th century. This idea of „nomadic” rock masses was soon accepted in Poland, and while it was still contested in the Eastern Alps, M. Limanowski wrote in 1905 „there are no mountains without nappes” and supported fully the idea of nappe structure of the Carpathians. At the same time, W. Teisseyre defined the western boundary of the East-European platform (1893, 1903, a, b), and published a fundamental characteristics of the tectonic style of platforms (1907), establishing later a precise notion of the tectonic nature of platforms, and determining the relation of their basement to the sedimentary cover (1921, 1922). W. Teisseyre should be regarded as the pioneer of Polish tectonic investigations of platform areas. The intensity of tectonic research increased greatly after the first World War. J. Nowak indefatigably pursued the study of the Carpathians; J. Czarnocki and J. Samsonowicz traced the major lines of tectonic structure of the Holy Cross Mts. The tectonic structure of the Polish lowland were analysed by M. Limanowski (1922), Cz. Kuźniar (1922), and B. Halicki (1935, 1938, 1939). Ideas on tectonics of salt domes expressed by B. Świderski (1922) were far ahead of their general acceptation in European literature. The results of investigations carried out during the period between the two World Wars were summarized in the synthetic papers of J. Nowak (1927, 1928, 1934) and Z. Sujkowski (1946). The paper by Z. Sujkowski provided a real basis for a logical analysis of the position of the western boundary of the Pre-Cambrian platform. The papers by J. N o w a k concerned the tectonic structure of the Carpathians (1927), the role and relations of Caledonian and Hercynian folding in Europe (1928), and the tectonic structure of the Polish lowland (1034); in the latter region several tectonic units then established are still accepted, while their nature has been precised in a more detailed way by research continuing in the post-war period. The way to the present state of knowledge of the tectonic structure of Poland was indeed paved by the research of W. Teisseyre and J. Nowak . Since 1945 the tectonic research developed at an continuously increasing rate. Geophysical methods were applied on a large scale, and bore-holes penetrated to increasing depth. The participation of Polish geologists in international programs for a tectonic map of Europe and of the Carpathian-Balcan range was stimulated. It is appropriate to begin the discussion of the development of tectonic research in Poland in the post-war period with the results of geophysical studies. The geophysical data interpreted by S. Pawłowski (1947, 1958, fide J. Znosko 1962 Fig. 2a), A. Dąbrowski (1957, Fig. 1) and J. Skorupa (1959 Tabl. 1) confirmed the existence and precised the course of a major tectonic line called „Berdo-Narol — Radom-Scania line”, „Tornquist line”, „lower Wisła line”, „line of deep-seated faults” (J. Znosko 1962, Fig. 3). Presently the author proposes to adopt the name „W. Teisseyre’s line” — stressing in this way his merits in the investigations of this zone and the priority in its determination. The first attempt at interpreting of the relief of the surface of the Pre-Cambrian basement east of the W. Teisseyre’s line was undertaken by A. Kisłow (1951 Plate VII) followed by A. Dąbrowski and K. Karaczun (1956, p. 343), S. Pawłowski (in: B. A r e ń and S. Pawłowski 1958, Plate 4), J. Skorupa (1959, Plate 1), J. Znosko (1959, 1962, Fig. 3) and many others. The first post-war structural-geological division of Poland was published by W. Pożaryski (1956, Fig. 1). This division was based upon superposed orogenic movements of Early Palaeozoic, Late Palaeozoic, Laramian and Tertiary age. During the preparation of the Tectonic Map of Europe S. Sokołowski and J. Znosko (1959a; 1959b, Fig. 1, Fig. 2 and Fig. 3; 1960, Fig. 1), presented another version of tectonic division of Poland. It has been based upon principles adopted for the whole Tectonic Map of Europe, i.e. on the idea of the last great folding of geosynclines or in other words on the idea of inversion of the geosyncline and consolidation of the area. A major modification of views on the tectonic structure of Poland was possible owing to new data obtained by geophysical methods and new deep bore-holes, which permitted a new tectonic interpretation of the Western Pomerania, and of the W. Teisseyre’s line, which is now regarded as the tectonic boundary separating the Pre-Cambrian platform from the Palaeozoic platform (J. Znosko 1962, Fig. 3, Fig. 4, Fig. 5, and Fig. 6). W. Pożaryski (1963) published a revised tectonic division of Poland (the Figure on p. 6), proposing a great number of tectonic (or structural — author’s remark) units. It is striking here that this author used the terms anticlinorium and synclinorium for tectonic units within the sedimentary cover of platforms. Later, W. Pożaryski pulblished still another version of the tectonic structure of Poland (1964, Fig. 1, Fig. 2 and Fig. 3). The principle of this division lies in the definition of rock complexes as the Caledonian cover, the Hercynian cover and the post-Hercynian cover, including, irrespective of their character, both folded rock complexes of géosynclinal origin, and not folded complexes of epicontinental origin. Joining again the discussion on the tectonic structure of Poland, the present author stressed the fundamental position of the idea of tectonic inversion in structural analysis and stated that the passage from the géosynclinal development to the epicontinental development constitutes the genetic and not the formal (e.g. restricted to the geometric point of view) criterion of division (J. Znosko 1966, Fig. 3). In the quoted paper much attention has been also devoted to the notions of anticlinorium and synclinorium misused, according to the present author, for structural units within sedimentary covers of platforms which posses all the characters of epicontinental development. Also J. Oberc (1957, Fig. 1) presented a tectonic division which should be noted because of the fact that this author did not differentiate the significance of structural stages of various origin e.g. built of geosynclinal and epicontinental complexes. This creates major difficulties in the construction of tectonic maps. J. Sokołowski published in 1958 a new tectonic division of the area of Poland, distinguishing five first-order regional units. Also this division does not take into account the inversion of geosyncline as the fundamental criterion. The preparation of the Geological Atlas of Poland in the scale 1 :2 000 000 for the 23-rd Session of the International Geological Congress permitted to incorporate new data into the picture of tectonic regionalization of Poland, presented on the map of tectonic units and on geological cross-section (J. Znosko 1968, Table 9 and Table 10). The new data confirm the older opinions on the existence of the so-called circum-Fennosarmatian Caledonides, precise the Teisseyre’s line and the western border of the Pre-Cambrian platform. It appears more and more clearly, that the basement of the area of Western Pomerania was subject to Caledonian consolidation, similarly as the Holy Cross Mts, which gradually are loosing their Variscan character. Also the basement of the Nida river trough, the basement of the Carpathian foredeep and of the Kraków—Silesia basin represent elements of Caledonian consolidation. The analysis of evolution of views on the tectonic structure of Poland should be terminated with the latest version of W. Pożaryski (1969, Fig. 1 and Fig. 2), again entirely different from the earlier views of this author. The distinguished units comprise the Pre-Cambrian platform, the Assynthian massif of Southern Poland, the epi-Variscan platform, the Sudetes, and the peri-cratonic depression, the latter being defined conformably to the opinions of N. S. Szatski and A. A. Bogdanov (1961), and A. A. Bogdanov (1961, 1962, 1964). The problem of the peri-cratonic depression, interpreted in various ways, is closely related with the question of existence or non-existence of the so-called circum-Fennosarmatian Caledonides. This question was thorouhly discussed on the International Conference of the Editorial Commitee of the Tectonic Map of Europe (J. Znosko 1964). W. Pożaryski oipted for a far extent of the Pre-Cambrian platform, reaching up to central England, and for the existence of the peri-cratonic depression. However available data do not confirm the existence of the peri-cratonic depression, especially if the original definition of E. W. Pawłowski (1959) is taken into account. In the contrary, there are indications that the basement of this „peri-cratonic depression” can be of various age, and that the Pre-Cambrian consolidation is not present on its entire area. Also the problem of the Assyntian massif of Southern Poland is difficult, as the presence of this massif is not marked in directly younger sediments. The sedimentary complexes of the Upper Riphean, sub-Holmia Cambrian, and Lower, Middle and Upper Caimbrian do not show freatures which would indicate the influence of the Southern Poland massif on their facial development. The present lack of Cambrian, Ordovician and Silurian sedimentary rocks on the „southern Poland massif” cannot be regarded as a proof of their previous absence there. The final elucidation of major tectonic problems as the position of the western boundary of the Pre-Cambrian platform the existence or non-existence of the circum-Fennosarmatian Caledonides, the extend of Variscan chains of Central Europe and of their foredeep, must be based upon stated, and not upon deduced geological facts. Deep bore-holes and geophysical studies will provide the answer. The key to the solution of these important problems is also in the hands of Polish geologists.