Skład granulometryczny skał okruchowych a ich pochodzenie

Abstract

GRANULOMETRICAL COMPOSITION OF THE CLASTIC ROCKS AND THEIR ORIGIN

Summary

There is a great divergence in classifications of rocks according to granulometrical composition. Controversial are both the boundary between the individual fractions and the interpretation of the results of granulometric analyses. In 1932, Trask presented a technique of calculating the sorting coefficient of sand and the asymmetry coefficient, and illustrated the results of granulometric analyses on histograms. It has commonly been accepted to present the granulometric composition of rocks in the form of cumulative curves, the shape and course of which are connected with the origin of deposit (Niggli, 1952). Basing on the sorting coefficient of sand and on the cumulative curves, Ruchin presented a diagram (1953), on which he distinguished the fields of fluvial, near-shore, bottom and eolian sands. On the basis of 10 000 samples studied, Passega (1957, 1963) gave a method of determining the depth, at which the rocks in study had been deposited. In addition, the paper gives also some technique of genetical interpretation of granulometrical composition of clastic rocks, and the examples of using the Passega's method in examination of the Dogger rocks from bore-holes Gorzów Wlkp. and Bąkowa.