Tektonika synsedymentacyjna jako czynnik warunkujący sedymentację formacji brunatnowęglowej w zapadliskach tektonicznych na obszarze zachodniej Polski

Jacek Robert Kasiński

Abstrakt


SYNSEDIMENTARY TECTONICS AS THE FACTOR DETERMINING SEDIMENTATION OF BROWN-COAL FORMATION IN TECTONIC DEPRESSIONS IN WESTERN POLAND

Summary
The paper deals with a system of tectonic troughs and depressions, developed in areas of mobile Paleozoic platform, including those of the Sudety Mountains (western Poland). The troughs and depressions generally follow old, Variscan or Cimmerian tectonic lines and the majority of them became tectonically rejuvenated in times of neo- Alpine (Tertiary) movements. Sedimentation of brown-coal formation became possible due to gravitational downwarping synsedimentary movements. Successive phases of these movements are reflected by cyclic character of the recorded sequences.
The Krzywiń and Złoczew troughs and Zittau Depression are the examples of influence of tectonic factor on sedimentary processes and, at the same time, of major structural types of Tertiary tectonic depressions: a narrow trough within a single block of the Paleozoic platform, subjected to epeirogenic subsidence and determined by a single tectonic direction (Krzywiń Trough), a trough developed in almost stable platform block (Złoczew Trough), and a depression affecting heterochroneous structures differing in tectonic orientation (Zittau Depression).
Comparisons of the nature of sedimentary sequences in each of the basins with those from their margins, carried out with reference to the recorded sedimentary megacycles, made it possible to identify mesocycles undoubtedly related to allocyclic diastrophic agents. However, it is still not possible to exclude effect of similar agents in other mesocyclothem sequences. Nevertheless, it should be noted that the mesocycles often appear related to the action of subrosion processes or, which seems even more common, compaction of strata forming lower part of a sequence. The latter process is especially clear and intense in the case of very thick peat deposits, where compaction may have been the major agent responsible for subsidence of depositional surface in brown-coal sedimentary basin.

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