Uwagi o karbonie północno-zachodniego obrzeżenia bloku przedsudeckiego

Halina Krawczyńska-Grocholska, Wojciech Grocholski




In 1970–1973 the authors made geological investigations in the northern part ofLower Silesia, the southern part of Wielkopolska, and the southern part of Ziemia Lubuska. They examined the cores of pra-Permian rocks from deep boreholes.

The results of studies by other authors were also taken into consideration. The Fore-Sudetic Block runs from the south-east to the north-west and dips to the north-west. Its northern and western boundaries are marked by sub-Tertiary

Permian outcrops (J. Wyżykowski, 1961) and by the deep dislocation zone of the Odra (A. Guterch, R. Materzok, J. Pajchel, 1973). On the north-west, the Fore-Sudetic Block borders the Żary Pericline, on the south-west – theSudetes, and on the north-east – the Fore-Sudetic Monocline. The Fore-Sudetic Monocline represents the Laramide structural stage, consisting of Permian and Mesozoic rocks. The Carboniferous, composed of terrigenous sediments, occurs in the basement of the Monocline and the Pericline. It is bordered on the north-east by phyllites of southern Wielkopolska. Epimetamorphic and Carboniferous rocks occur under the Rotliegendes. The top of phyllites was drilled at a depth of 2 200–2600 m. Sporomorphs, identified by H. Krawczyńska-Grocholska, indicate that these deposits are of Old Palaeozoic age.

The depression that occurs between the Fore-Sudetic Block and the Metamorphic Massif of southern Wielkopolska has the form of a furrow. The axis of that furrow and of the ridge of metamorphic rocks run from the south-east to the north-west. The furrow is filled with sediments of the Carboniferous and the Rotliegendes. Palynological studies by the authoress show that the sporomorph assemblages represented here range from the Upper Devonian to the Upper Carboniferous inclusive.

Cambrian deposits, palaeontologically evidenced by S. Cieślinski (Klepinka borehole), occur in the area of the Variscan Fore-Sudetic Furrow. The stratigraphic gap that follows comprises the Ordovician, Silurian, and Devonian. Upper Devonian and Tournaisian rocks were redeposited during the Visean. Granitoids of the dislocation zone of the Odra are regarded as Variscan, probably Carboniferous.

The margin of the Fore-Sudetic Block was affected by tectonic movements during the Bretonian, Late-Variscan, and Laramide phases. The sub-Permian surface is morphologically differentiated. Parallel elevations of a south-east – north-west trend can be distinguished here; they are composed of the folded sediments of the Carboniferous and the Metamorphic Massif of southern Wielkopolska. These elevations are intersected transversely by theBielawyValley(J. Sokołowski, 1967) and a lowering which runs from Leszno to the south and then to the east – following the axis of the Fore-Sudetic Block.


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