Tektoniczne pochodzenie wschodniej części Kotliny Nowotarskiej

Henryk Niedzielski


Tectonic origin of the Eastern Part of the Valley of Nowy Targ

Bore holes near the river Dunajec between Dębno and Frydman in the eastern part of the valley of Nowy Targ indicate that in the environs of Dębno the slopes of the Gorce Mts. continue as a socle under the Holocene accumulation terraces. The border of this socle extends between Dębno and Huba roughly parallel to the present course of the Dunajec. A fragment of an analogous socle was found underlying a terrace of the Baltic glaciation on the opposite side of the Dunajec at the prolongation of the northern slope of Szubienicza Góra. Between these socles (Fig. 1) there extends a trough filled with Quaternary deposits ca. 100 m thick. In these deposits three lithological complexes may be distinguished, denoted by leters „a”, ,,b” and ,,c”. In the bore hole F 2 Baltic fluvioglacial deposits have been found overlying the complex ,,b” (Fig. 2). The complex ,,a” consists of gravels containing 90 to 100 per cent of the Lower Triassic quartzites from the Tatra Mts. Rare fragments of the Tatra granites are strongly altered. The complex ,,b” is also composed of gravels but contains more fragments of Tatra granites (up to 30 per cent). This complex is characterized by the presence of intercalations of clays and silts. There appear also layers composed exclusively of fragments of flysch rocks. In the bore hole F 2 the complex ,,b” is overlain by gravels consisting of 52 per cent of grey Tatra granites, 28 per cent of Tatra quartzites, 17 per cent of flysch sandstones and 3 per cent of limestones and other rocks. The gravels are referred to the Baltic glaciation (Wiirm). The uppermost complex ,,c” consists of gravels composed mainly of fragments of gray Tatra granites. Fragments of the Lower Triassic quartzites and of flysch sandstones constitute less than twenty per cent. The age of these deposits is Holocene. The complexes ,,a” and ,,b” belong to the Pleistocene; the petrographical composition of the former complex suggests that it may be connected with the Cracow glaciation (Mindel). The above described Quaternary deposits overlie the Neogene probably Pliocene, developed as gray green days, and silts containing small amounts of fine gravel composed of poorly rounded fragments of flints, quartzites, gray marls and light gray radiolarites. In bore hole F-2 there were 26 m of these deposits but their bottom was not reached. The age of the above described deposits was established on plant fossils. The author suggests that the presumable Pliocene found in bore hole F 2 and the Pliocene of Huba have been deposited in the same basin (Fig. 1). Subsequent tectonical movements disturbed the continuity of these deposits. It follows that after the Pliocene and before the deposition of the complex „a” (Mindel?) there was formed a graben ca. 100 m deep (Fig. 3). This agrees with the opinion that the eastern part of the valley of Nowy Targ was of tectonic origin.

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