Cechy teksturalne osadów czwartorzędowych rejonu Gozdnicy

Dominik Jura, Janusz Trzepierczyński

Abstract


Przedstawiono charakterystykę uziarnienia osadów czwartorzędowych, które interpretowano za pomocą krzywych probabilstyczno-kumulacyjnych według zasady G.S. Vishera (1969). Badania te umożliwiły uszczegółowienie warunków sedymentacji i wyróżnienie obszarów depozycji dla utworów pochodzenia rzecznego. Wykazano również stosunkowo niewielką przydatność parametrów granulometrycznych dla genetycznego rozdzielenia utworów czwartorzędowych z rejonu Gozdnicy, bardzo ujednoliconych w wyniku wielokrotnej przeróbki w różnych środowiskach sedymentacji.

TEXTURAL FEATURFS OF QUATERNARY DEPOSITS IN THE GOZDNICA REGION

Geological units differentiated in the course of geological mapping are characterized on the basis of 150 granulometric analyses.

Till from southern Gozdnica region is sandy-gravel. with polymodal grain-size distribution (Fig. 2, curve 1), and it represents bottom moraine, whereas that from the northern region is sandy, with unimodal, flattened grain-size distribution.

Three granulometric types of fluvioglacial sands and gravels are differentiated: coarse- and fine-grained gravels and coarse-grained sands. Phi values obtained for these deposits (Fig. 2, curve 2) indicate the Presence of four population of transported sediments (dragging, saltation, suspension and glacial), with shortage of coarse sand fraction.

Sands and muds of the Kwisa ancient valley are characterized by symmetrically steep distributions (Fig. 2, curve 3), with modal class for phi equal 2. Graphs for sandy-gravel deptosits are similar to four populations curves of fluvioglacial deposits.

Sands and gravels of aggradational, 12 - 18 m terrace of the Nysa Łużycka River are characterized by phi = 0 for coarse grains and phi = 3.25 for fine ones. Such values correspond to sand mainly transported by saltation.

Sands and gravels of 3 - 7 m terrace of the Nysa Łużycka River (Fig. 2, curve 5) are characterized by the type of curve typical of channel sediments deposited in ox-bow bars.

Eolian sand (Fig. 2, curve 6) are characterized by break point for coarse grains with phi = 6, indicating unifonn, high intensity of deflation.

Sands and gravels of 0.5-3.0 m terrace or the Nysa Łużycka River (Fig. 3, curve 7) may be treated as deposits of channel of meandering river (Phi = 0) or outside-channel deposits (phi = :2 or 3.25).

In order to compare the studied deposits, the results of analyses were plotted in the form of histograms (Fig. 3) of individual granulation indices: GSS, GSO, GSP, and GSK.

The methods of granulometric analyses appeared insufficiently sensitive to sHow differences in origin of deposits made similar to one another by repeated reworking under different sedimentary conditions in the Gozdnica area. Because of similarities in granulometric developments, sedimentological and paleogeographic criteria were used. The latter appeared effective for differentiation of Masovian-Podlasian (Warta) Stadial deposits of the Kwisa River valley, those of 12-18 m terrace of the Nysa Łużycka River and eolian sands in , the field in the course of the mapping works.


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