Utwory czwartorzędowe w otworze wiertniczym Wróblówka na Podhalu

Abstract

QUATERNARY FORMATIONS IN BORE HOLE WRÓBLÓWKA, PODHALE REGION

Summary

Bore hole Wróblówka, situated on a 5 m thick bed of Holocene alluvial deposits of the Czarny Dunajec river, pierced the Pleistocene deposits (5-117 m) showing some gaps in these formations caused by erosional process (Fig. 2). These deposits may have been formed and completely preserved only due to a continuous, although irregular subsidence of the Nowy Targ basin bottom. Such an irregularity was a result of the displacement of the moment of the maximum plunging from the Pieniny Klippen Belt to the Gorce Mts. (at present about 4 km north of Wróblówka), and a result of the piling moment behind it (at present in the Pieniny Klippen Belt). Both faunistic and floristic representatives, found to occur in the formations encountered by drilling, are not uniform in their stratigraphical meaning. Palynological examinations of a sample taken at a depth of 116,5 m, made by J. Oszast and L. Stuchlik in 1970, demonstrate a fragmentary pollen spectrum of a cool period. This spectrum, resembling that from Mizerna, has been related by the present author to Günz. Samples taken at a depth of 50,0 m show a fragmentary spectrum of the warmer period, most probably of an interstadial one. Fluvioglacial deposits, found at a depth of 5-13,0 m, closely related to the peat bog Baligówka, were formed in a period between the Pomeranian phase and Allöred (Fig. 2). At the Preboreal time the Dunajec river bed was developed in the f1uvioglacial deposits with their previous thickness equal to 15-20 m. The underlying formations, down to 113,5 m, i.e. fluvioglacial deposits, ice-dammed lake deposits and fluvial deposits, developed in several horizons, belong to the remaining Pleistocene periods, thus they must have been formed between the Pomeranian phase and Günz. Their stratigraphical subdivision has been made on the analysis of grain size distribution, on petrographical examinations, and on the analysis of the weathering state of the material coarser than sand.
Processes active in the Nowy Targ Basin and in the adjacent area developed in the individual periods of the Pleistocene as follows. In a transition period to the glacial time the erosional basis of the Dunajec river was uplifted according to the cooling of climate and advance of ice sheet. Waters, already in smaller amounts, washed out and graded the earlier sedimented alluvial deposits with predominating rocks of Tatra Mts. At that time bedded water deposits were laid down, with the predominance of finer and finer quartz grains upwards and with quartzites. At the glacial time the Tatra material hardly flowed into the Nowy Targ basin, since glaciers tied not only water but also rock material. The dammed flow and a surplus in the tectonic subsidence of the basin were favourable to the formation of the ice-dammed lake deposits and limnic deposits. Sandstone material flowed from the Gorce Mts. and from the Podhale region, which, deprived of plant cover and ice sheet, underwent denudation processes. This can be observed in the profile by an increased amount of sandstones and quartz from these sandstones in the formations resembling varves, and in the overlying fluvioglacial deposits (Fig. 1). The warming up of climate at the transition periods to interglacials or interstadials, and at the beginning of these periods, generally preceded the similar phase of warming up, north of the Carpathian Mountains, a phase related to melting ice sheet. A rapid melting developed at first within firn fields in the Gorce Mts., and then the melting comprised also glaciers in the Tatra Mts. This was accompanied by a quick infilling of the basin with the sandstone material, later on with variously grained, mainly crystalline materials of Tatra origin, with an admixture of the Podhale sandstones. After withdrawal of the glaciers the transportation power of water considerably decreased, and these deposits were covered with loams. When the lowered erosional base level of the Dunajec river reached the region of Wróblówka, erosional terraces and the Dunajec river bed were formed. At the Interglacial time the erosional-accumulative processes were markedly insignificant, additionally hampered by plant cover.