Osady i struktury peryglacjalne w klasyfikacji stratygraficznej czwartorzędu Polski

Abstract

Osady i struktury peryglacjalne są istotnym składnikiem czwartorzędu Polski i stąd potrzeba uwzględnienia ich w klasyfikacjach stratygraficznych. Elementy peryglacjalne mają największe znaczenie w podziale klimatostratygraficznym. Procesy zachodzące w rytmicznie powtarzających się okresach zimnych znajdują wyraz w elementach glacjalnych i peryglacjalnych. Ze względu na dużą wagę podziału klimatostratygraficznego dla budowy klasyfikacji chronostratygraficznej istotna jest rola elementów peryglacjalnych także w tej klasyfikacji. Ważne znaczenie mają zarówno osady. jak i autonomicznie ujmowane struktury peryglacjalne w klasyfikacji Iitostratygraticznej. Najmniejsza jest rola tych elementów w biostratygrafii.

PERlGLACIAL SEDIMENTS AND STRUCTURES IN STRATIGRAPHIC CLASSIFICATION OF THE QUATERNARY IN POLAND

Periglacial elements are highly important components of the Quaternary in Poland., used in all the major strarigraphic classifications. From the point of view of stratigraphy, it is possible to speak about two major periglacial elements, i.e. periglacial sediments and structures. Although structure is one or features of sediments. It is justified to treat periglacial structures as an autonomous element The structures represent effects of periglacial phenomena and they are developed in both periglacial sediments and, as epigenetic features, in older, non-periglacial ones.

Periglacial elements play highly significant role in climatostratigraphic subdivision which is regarded as especially important stratigraphic subdivision of the Quaternary. In accordance with the principles of climatostratigraphy, sediments are divided with reference to climatic conditions under which they originated. In the case of the Quaternary this is subdivision into sediments accumulated in cold and warm periods. J. Dylik emphasized bipartity of those formed in cold period, making possible their further subdivision into glacial and periglacial ones. Such subdivision appears justified formally and on its merits. When appropriately used it is advantageous for arrangement of uniform and, at the same time, more rational stratigraphic subdivision than hitherto used for the Quaternary of Poland.

The chronostratigraphic classification of the Quaternary is mainly based on the climatostratigraphic subdivision. Significance of that subdivision makes indirectly periglacial elements also so important for chronostratigraphic classification. The image of cold stages (substages?) comprising sediments accumulated during cold periods will not be complete unless periglacial elements are taken into account along with the glacial ones.

Perigiacial elements are also important for lithostratigraphic classification. especially when it takes into account genetic factor. Attention should be also paid to a specific position of periglacial structures in that classification. The need of somewhat autonomous treatment of periglacial structures in relation to periglacial elements has been already stressed. Epigenetic perigiacial structures, especially those of the fissure type and related to thermal contraction, should be differentiated as separate stratigraphic units - cryohorizons. When it is desirable, there may be differentiated units comprising two or more cryohorizons. The name cryozone is here proposed for the latter units. All the units may he put together with lithostratigraphic sensu stricto and pedostratigraphic ones as lithostratigraphie units of a higher order.

The share of periglacial elements is the smallest in the case of biostratigraphy.