Własności fizyczne skał obniżenia podlaskiego

Adam Dąbrowski




As compared with the other regions of Poland, the area of the Podlasie depression is characterized by a large amount of determinations of physical properties of rocks (density, porosity, magnetic properties), which are the results of the measurements made by the Enterprise of Geophysical Prospections to the order of the Geological Institute. Based on these materials the present author has calculated the maximum, minimum and medium values of the effective porosity Pe, volume weight of the water-saturated samples σ, magnetic susceptibility χ and Königsberg's coefficient Q for the individual formations found to occur within the Podlasie depression and has presented them in tables (Figs. 2–9). Their course show that a distinct relation exits between the occurrence depth or facial development, and the mean value of density of the sedimentary rocks within the Podlasie depression. An anomalous increase in density of numerous formations in the region of Mielnik-Rajsk, which does not have relations with any of these factors, is highly interesting here .The author gives the possible grounds of this phenomenon. The Eocambrian formations of the effusive series within the Podlasie depression are, as concerns their magnetic susceptibility and density, highly differentiated. Their series, beginning with those which are cheracterized by the lowest susceptibility and are the lightest, and ending with those which are distinguished by the highest susceptibility and are the heaviest, may be arranged as follows: arkoses, tufs, tuffites and tufgenous sandstones, conglomerates, agglomerates and breccias, basalts and diabases. It is difficult to make a similar arrangement of the crystalline Proterozoic-Archaean formations of the Podlasie depression there. Only granitoids are distinguished here by a relatively low density and magnetic susceptibility. Other metamorphic rocks of the mean and deep zones of metamorphism (gneisses, amphibolites, granulites, migmatites, hornfelses, charnockites) and metamorphic rocks of shallow zones (schists) are cheracterized by the physical properties of the same values.

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