Onkolity jurajskie w okolicy Lipy (SE Polska)

Abstract

 Omówiono górnooksfordzkie onkolity z otworu Lipa 2. Z przeprowadzonej klasyfikacji wynika, że onkoidy wzrastały w warunkach strefy napływowej, podlegały krótkiemu transportowi i zostały złożone w obrębie tego samego środowiska sedymentacji.

JURASSIC ONCOLITES IN THE VICINITIES OF LIPA (SE POLAND)

The paper deals with Upper Oxfordian oncolites found in core material from the borehole Lipa 2 (Fig. 1). The classification of macrooncoid forms, carried out using subdivision proposed by K. Dahanayake (1977), showed predominance of elements of the type III. The elements are accompanied by markedly less numerous compound oncoids of the type IVC and occasional simple oncoids of the type H. Such typological composition of oncoid structures suggests (K. Dahanayake, 1977, 1978) their growth under conditions corresponding to those of depressions in supratidal zone. Redeposition of oncoids (into somewhat deeper but not distant zone) resulted in their secondary concentration and, therefore, origin of oncolites. The transport was, however, limited to the same sedimentary environment.

That is why one should be careful in interpretating carbon ante sedimentary environments in the case of some Jurassic oncolites.