Uwagi o pozycji stratygraficznej Eleutherophyllum mirabile (Sternb.) Stur w Górnośląskim Zagłębiu Węglowym

Abstract

REMARKS ON THE STRATIGRAPHICAL POSITION OF ELEUTHEROPHYLLUM MIRABILE (STERNB.) STUR IN THE UPPER SILESIAN COAL BASINSummaryThe paper presents data on the occurrence of the species Eleutherophyllum mirabile (Sternb.) Stur – a fossil characteristic of the Namurian A in the substratum of the productive formations of the Upper Silesian Coal Basin (Table I).The forms of Eleutherophyllum mirabile (Sternb.) Stur and the guide species of fauna and flora found in the deposits pierced by boreholes Sosnowiec IG-l, and Goczałkowice IG-l allow us to establish more precisely the position of the first appearance of this species, as compared with the goniatite horizons and with the stratigraphical ranges of other guide flora species.In the light of the facts presented, and according to the papers already published some specimens of Eleutherophyllum mirabile (Sternb.) Stur, found within the Polish part of the Upper Silesian Coal Basin, are stratigraphically the oldest finds of this species. They appear beneath the deposits referred to the Gog1 goniatite sub-horizon, most probably already within the Gob horizon. A dozen or so metres below the layers with the species considered a gonitite horizon has been documented.In addition to Eleutherophyllum mirabile (Sternb.) Stur the two boreholes in study reveal other key flora species, or those characteristic of the Namurian A, i.e. Diplothmema (Heterangium) adiantoides (Schloth.) Goth., Lyginodendron fragile (Schloth.), Sphenophyllum tenerrimum Ettingsh. and Stigmaria stellata Goepp.Eleutherophyllum mirabile (Sternb.) Stur occurs in these two boreholes along with the species of the Visean flora: Lyginodendron dicksonioides Goepp., Diplothmema (Heterangium) dissectum (Brongn.) Stur, Sphenopteridium pachyrrachis (Goepp.) Kidston, Sphenopteridium biffidium (Lindl. et Hutt.)Benson, Sphenopteridium silesiacum Patt., Sphenopteridium dissectum (Goepp.) Schimper, Neuropteris antecedens Stur and Archeocalamites scrobicalatus Schloth.) Stur.Conclusions: a – a fact has been proved that the phytostratigraphical boundary between the Lower and the Upper Carboniferous does not coincide with that between these subsystems, based on the zoostratigraphical criteria, as it has been ascertained in the top part of the Silesian-Moravian profile of the Culm deposits (E.Purkynova, 1970);b – the occurrence of Eleutherophyllum mirabile (Sternb.) Stur and of some other guide species of the Namurian A flora begins already at the Gob goniatite horizon;c – on account of scarce floristic materials the problem of the phytostratigraphical boundary between the Visean and the Namurian, and its correlation with the goniatite horizons requires additional studies;d – in the light of the materials presented, the floristic criteria necessary to single out the Namurian A (the problem of guide and characteristic fossils) also call for additional research works;e – a relatively great divergences of the phytostratigraphical and zoostratigraphical boundaries between the Visean and the Namurian, and the use of a uniform chronostratigraphical nomenclature, lead in the stratigraphical studies to a marked confusion, therefore a new name should be introduced to determine the lower part of the Namurian A, based on floristic criteria, as it has been proposed by W. Remy and V. Havlena (1962) for the Upper Devonian and the Visean (Arctunesian and Sorabian), or separate floral zones denominated after index fossils should be employed.