Konkrecje związane z kanalikami U-kształtnymi robaków w spągowych warstwach aalenu świętokrzyskiego

Abstract

CONCRETIONS CONNECTED WITH U-SHAPED WORM BURROWS IN THE AALENIAN DEPOSITS OF THE ŚWIĘTOKRZYSKIE MTS.SummaryIn the shallow-water marine sandstones, belonging to the lower part of the Aalenian deposits of the Świętokrzyskie Mts., are found concretions that resemble a truncated cone whose base is directed upwards (Tables I–IV, Figs. 1a–5). Height of the objects here examined is from 5 cm to 113 cm, their diameter being in the upper part from 4 cm to 13 cm.In the middle of each concretion a more or less distinctly preserved U-shaped worm burrow can be observed, revealing traces of vertical displacement of an animal. The shape of the burrows corresponds to the form distinguished by Swedish scientists and named Diplocraterion. It results from the author's observations that the concretions here considered occur in the beds of a feebler concentration of the Diplocraterion burrows. However, in places where the burrows are numerous, as it can be seen on Table V, Figs. 7a and 7b, they are absent. The origin of the concretions is probably connected with the organic substance that accumulates in the sand surrounding the Diplocraterion burrows and is favorable for impregnation of the rocks with iron sulphides. In places where the net of burrows is denser, the deposit is regularly impregnated with organic substance, thus with iron sulphides that are responsible for the formation of the concretions.