Region łysogórski a platforma wschodnioeuropejska w cyklu kaledońsko-waryscyjskim

Henryk Tomczyk



At the present stage of studies, the idea of subdivision of the Holy Cross Mts in to the Łysogóry and Kielce regions (4), appreciated by Samsonowicz (9, 10), appears to be of marked importance for geophysical-geological search for oil and gas in central Poland (Fig. 1). In the Early Paleozoic, the Łysogóry region was stable and characterized by sedimentation of the platform type. It did not take part in large-scale strike-slip movements along the Trans-European Fault (TEF) (3). The movements affected the Małopolska Massif (MM), formed in the Early Caledonian cycle (11, 12). Upper Cambrian claystones with trilobites L. latus are known from northern slopes of the Łysogóry Range (E. Tomczykowa 1968) as well as platform outcrops in the Tajna Fjord (Norway) (6), situated 3-5 km from the front of Caledonian overthrust (Fig. 2).
The movements along TEF were continuid from Middle Cambrian Świętokrzyska phase (11) till the Emsian. They could temporarily cease in the Late Silurian as the Mazury-Byelorussian treshold, separating a shallow ostracod Baltic basin and the Podlasie-Lublin embayment characterized by predominance of graptolite facies (11, 14), became uplifted after the Ludlowian (Fig. 2). In the Łysogóry region, Late Caledonian movements resulted in disappearance of graptolites and deposition of mudstones and rocks of the Rzepin Beds with benthic fauna (4, 14). Coeval Silurian rocks developed in nearshore carbonate facies in eastern and northern Poland display affinities with those in Volhynia and Podolia (Figs. l, 2). The Late Caledonian movements could also initiate formation of the Podlasie-Brest Depression (trough), connected with the Pripyat' Trough and, during the next stage, Dnepr- Donets Aulacogen (l, 5, 7).
Synorogenic movements of the Cracow and Ardennian phases ( 11) did not break sedimentation of the Silurian and Lower Devonian (Gedinnian, Siegenian) in marginal part of the platform as the Oldred facies (ending the megacycle of marine sedimentation) began to predominate in Europe after the Erian phase. This interpretation is further supported by continuity of the Silurian and Devonian. The transitional beds are assigned to regional stages such as the Podlasie, Rzep in, Bostów, and Ciepielów stages in the Łysogóry region and the equivalent ones (Skała, Berszezów and Czortków stages) in Podolia (4, 10, 11, 14). The strata remain unknown in the Kielce region and other parts of the Małopolska block.
The position of the Łysogóry region and its tectonic contact with the Kielce region became changed in the Late Paleozoic. At a ceremonian session dedicated to J. Samsonowicz, held on May 18, 1985 at Ostrowiec Świętokrzyski, and in lectures dalivered in Warsaw and Wrocław in 1986 (12), the Author presented a hypothesis that the old East- European Platform extended originally as far as the Łysogóry region. In the Bretonian polyphase, intense strike-slip movements took place and the Podlasie-Brest Depression became extended eastwards as far as the area of tensional Pripyat' Trough (5, 7). East of that trough, clastic-salinary sedimentation was continuing from the Frasnian till Middle Famennian and a 3-4 km packet of rocks originated. The rocks cannot be correlated with those from the Volhynia- Podolia area nor those from the Vilnius-Minsk region, i.e. north of the trough. The Pripyat' Trough, formed at that time, passes to SE in to the Dnepr-Donets Trough of the rift type, and a wide fault zone separates the Ukrainian Shield from the rest of the Russian Platform. The shield was presumably shifted to NW and WNW, obliquely breaking margin of the old platform and, therefore, TEF. South-eastern Poland became affected by Early Variscan movements in area from northern margin of the Podlasie Trough as far as the boundary of Volhynia and Podolia and the Włodzimierz Fault. Section of the Famennian show that in the Lublin and Łysogóry regions the movements were most intense in Middle and Late Famennian. This was the time when the Kielce and Łysogóry regions became different in facies. The Clymenia facies was characteristic of the former and so-called facies of knobby limestones (4) of the type of the Firlej Fm. in the Lublin area, up to l000 m thick and with features of submarine slumps (1, 8, 9, 11, 12) - for the latter. At that time the Łysogóry anticline became overthrusted from NNE to SSW on the Kielce-Łagów syncline. TT zone (line), heterochroneous in some sections in relation to TEF, originated after the Bretonian movements, without any change in structure of the Holy Cross Mts (12, 15). In conclusions it should be stated that a tectonic model identical with that linking origin of the Rhine Graben and Rhine Trough with activity of transform fault, proposed by Bergerat (2), is here accepted for explaining the origin of the Dnepr- Donets Aulacogen, because of similarity in tectonic processes.

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