Goniatyty wapienia węglowego z Gałęzic

Abstract

Goniatites from Carboniferous Limestones at Gałęzice (Holy Cross Mountains) Lower Carboniferous deposits at Gałęzice were discovered by J. Czarnocki (1916). Among the provisionally determined fossils he -mentioned Glyphioceras sphaericum (?) Mart. In the years 1965—69 the present author examined a Carboniferous Limestone exposed in a railway cut in a quarry at Gałęzice (Fig. 1). Among the rich fauna found on the spot, there were numerous specimens of goniatites. I am greatly indebted to Professor Mackenzie Gordon Jr. of the Smithsonian Institution and to dr Karol Bojkowski for the helpful discussion, and to Professor Henryk Makowski, who kindly let me use their comparative specimens. Description of the outcrop Carboniferous Limestone forms a range of hills of a NW—SE direction in the Gałęzice region. The limestone is underlined by dark shales with tuffite intercalations, radiolarites and phosphorite concretions. A complex of greywacke shales with plant detritus overlies the limestones. Most probably, all isolated packs of the Lower Carboniferous limestones were deposited at the same period. The outcrop under consideration was made in an elongated hill of a NW—SE direction, and is about 120 m long and up to 2,5 m high; in the eastern part it is nearly parallel to the strike of layers; in the western one, at a distance of 20 m, it traverses almost the whole limestone complex. The contact of limestones with the underlying shales and the overlying greywacke series is not visible. As well as in other outcrops, it is probably of a tectonic character (H. Żakowa , 1971). The Carboniferous Limestone is composed of three different complexes of sediments. The lowest complex is built of three layers of gray organodetritic limestone with graded bedding, about 2 m thick. Fossils which occur in them are generally broken; phosphorite concretions which come from the underlying Culm shales are also found there. A single specimen of Goniatites crenistria has been found in this complex. The layers have a strike of 285°— 290°, and dip of 24°—35°N. The top surfaces are distinctly marked. Above, there is a second complex of limestones, 2,5 m thick which lack a distinct bedding. They are intensively fractured, and in the middle part of the outcrop they display distinct changes connected with circulation of mineralizing solutions. Horizontally, the limestones display great lithological changeability. There occur here lenticles of black claystones with thick crinoide fragments, solitary corals, and aglomerations of complete shells with preserved destructible elements, such as spines of Productides. There also occur accumulations of small, usually damaged shells and fragments of shells which display a certain sorting. The types of accumulations of organic remains, mentioned above, occur among bigger colonies of branched corals up to 40 cm high, among smaller colonies of Tabulatae and massive shells of Gigantoproductus. In the latter, accumulations of trilobite tests were found. Phosphorite concretions, their fragments, and a piece of carbonized wood were found in black claystones and in limestones. In the sediments under discussion there is a certain regularity of distribution of organic remains in the stratigraphie sequence. The number of coral colonies and big brachiopods decreases towards the top of the complex. Limestones of the second complex form a biostrome made up of corals, stromatoporides and brachiopods. The limestones contain a great number of shells of moving organisms such as snails, molluscs, conularies, trilobites and cephalopods. The majority of the goniatite specimens described in the present paper were found in this series. The third complex comprises gray limestones; in the lower part they are of lithological character similar to the top part of the second complex. The limestones contain, however, big, up to 1,5 m high, colonies of corals in their living position. The upper part of the third complex is built of crynoidal detritic limestones, resembling limestone layers of the first complex. The sedimentary conditions of the Carboniferous limestones of the outcrop here discussed will be dealt with in a forthcoming paper. Remarks on Ecology of Goniatites of Carboniferous Limestones at Gałęzice While compared with other fossils, the goniatites are in the minority. Jn the outcrop described the goniatites, however, are much more numerous than in other outcrops of the Carboniferous Limestone at Gałęzice. Their species composition is very differentiated: as many as 5 species can be distinguished among 20 specimens, all of them having a relatively thin shell. The fact that they have been preserved in the described limestone complex, as well as that they are absent in majority of organodetric limestones of the Gałęzice Carboniferous is probably connected with their being an autochthonic element of fauna on that area. They had lived on, or above the bottom together with corals, brachiopods, trilobites', and had searched for food on that area. Quick sedimentation in that region allowed preservation of their delicate shells in sediments. Characteristic traces of injuries on certain shells of brachiopods also indicate that goniatites are an autochtonie element. On 3 specimens of Pseudoleptaena distorta (Sowerby) there are symmetrical and deep injuries (PI. XXIV, Fig. 5). They appear on both valves at a diameter of about 8 mm, yet the specimen managed to survive, reaching a diameter up to 20 mm and the damaged place was healed. At the same time, however, the normal ornamentation of the shell was disturbed. The injuries of shells happened through two symmetrical, conically-pointed elements of a beak type. It seems probable that all injuries observed on the immature specimens of Pseudoleptaena had been caused by goniatites feeding on that area. The dimensions of the described Goniatites amounted to 40 and 60 mm, which allowed them to attack the brachiopods of dimensions from 6 to 8 mm. Conclusions 1. The Carboniferous limestones of Gałęzice were formed in the subzone Goa and, most probably, in its upper part. 2. Identical position of the Lower carboniferous sediments of Gałęzice in the profile, similarity in thickness and in the composition of fauna point out that the limestone lenticles are fragments of a tectonically disrupted layer. The layer was formed as a result of a uniform, organogenic sedimentation which occured on the whole area at the same time. A similar conclusion was also presented by J. Fedorowicz, (1971). 3. Most probably, the goniatites are an autochthonic element of the fauna.