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Znaczenie analizy minera ów ci kich w badaniach osadów czwartorz dowych Polski

DOI: 10.2478/v10066-008-0001-1

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Abstract:

In most regions of Poland the composition of heavy minerals assemblage permits to distinguish the Quaternary deposits from the older ones. The pre-Quaternary deposits are characterized by high content of glauconite, carbonate-ferruginous-manganese concretions, muscovite and chlorites. In their transparent heavy minerals spectrum the following minerals predominate: zircon, tourmaline, rutile, staurolite, disthene. However, the Tertiary deposits in the Carpathians and their foreland contain a significant amount of garnet, and sometimes also amphiboles, pyroxenes and biotite. Pyroxenes and sillimanite are found in the Sudetes foreland. In many Tertiary deposits of the northwestern and western Poland there are rather high contents of amphiboles, biotite, pyroxenes, garnets, rutile. In all Quaternary deposits in Poland the qualitative composition of heavy minerals assemblage is similar but the contents of particular minerals are different depending on the examined grain fraction. In tills (Table 1) and glaciofluvial deposits (Table 2), with the decreasing grain diameter the contents of zircon, rutile, and partly epidote increase, and those of amphiboles and garnets decrease. In rubble of coastal zone in the Polish Baltic Sea, with the decreasing grain diameter the contents of zircon, rutile and epidote increase, and those of amphibole, biotite and pyroxenes decrease (Tables 3-7). In Poland, glacial, glaciofluvial and glaciolacustrine deposits are characterized by quantitatively similar composition of heavy minerals assemblage. Amphiboles, biotite, epidotes, garnets and pyroxenes are typical transparent minerals (Tables 8 and 9). Young Pleistocene and Holocene sands of river terraces and dune fields in the upland zone of Poland differ from glacial deposits in low contents of amphiboles, biotite and pyroxenes, and higher contents of garnets and epidotes (Tables 8 and 9). Fossil river and lacustrine deposits of Polish Lowlands have very similar assemblage of heavy minerals to that found in glacial deposits. Both glacial and glaciofluvial deposits have similar composition of heavy minerals assemblage irrespective of their age (Tables 10, 11 and 12). This principle concerns also loesses (Table 13a, b) but the youngest ones are characterized by higher contents of amphiboles and epidotes. The composition of heavy minerals assemblage is useful for determining the source of material forming the Quaternary deposits. In the case of glacial deposits, the enrichment in glauconite, chlorites, and even zircon, rutile, tourmaline, staurolite indicates that material from local older substratum was supplied to the Quaternary deposits. Heavy minerals spectrum of non-glacial deposits can directly indicate the source material that formed a deposit. Conversely, it is difficult to draw the conclusions about fossil and modern weathering-soil horizons in loesses from the composition of heavy minerals assemblage (Tables 14 and 15). The results of heavy minerals analysis are us

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