Microflora prekambryjskich wapieni okolicy Dusznik Zdroju (Sudety Środkowe)

Abstract

Microflore of Pre-Cambrian LImestones of the Duszniki Zdrój Region (The Central Sudeten) Metamorphic rocks of the Bystrzyckie Mountains, which also comprise crystalline limestones of Duszniki Zdrój, have been known to many authors. H. Wolf (1864) included these rocks among the Pre-Cambrian; at the same time he distinguished red and augen gneisses as older ones, while mica-schists with limestone lenticles, hornblende schists and gneisses were considered to be younger ones. L. Lepla (1910) included metamorphic rocks of this region among the Archaean. W. Petrascheck (1910, 1944) distinguished the older, axial part built of gneisses, and the younger one — a cover of mica-schists with limestone lenticles; he included both parts among the Pre-Cambrian. K. Smulikowski (1951) included mica-schists among the Algonkian, with a reservation, however. J. Gierwielaniec (1957, 1965) supposes that crystalline limestones of the Duszniki Zdrój region are of the Cambrian age, although their affiliation to the Algonkian is not unlikely. A synthetic stratigraphical-lithological profile of metamorphic rocks of the Bystrzyckie Mountains was drawn up by M. Dumicz (1964). This author includes the metamorphic rocks of the Bystrzyckie Mountains among the Pre-Cambrian; at the same time he remarks that micaschists with limestone lenticles are older than gramte-gneisses. J. Obere (1966) included mica-schists of this region among the Proterozoic, while H. Teisseyre (1968) claims their Pre-Cambrian age. The author of the present paper has carried out his studies in one of non-working limestone quarries situated in the Duszniki Zdrój region (fig. 1). Shaly limestones, compact and brecciated, dark-pink and lightgray in colour occur in this outcrop (fig. 2). In .microsections directional arrangement of mineral grains have been found (table I, fig. 1, 2), among which calcite prevails, quartz constitutes about 25%, while micas and feldspars are less numerous. Ferric oxides form pigment that gives colour to the rock. Brecciated limestones are outcropped on one of the walls (table I, fig. 3). Samples for micropalaentologic studies were taken from all outcrop ped layers. The samples were used for making cubes of a size 8 X 5 X 6 cm; the latter were then dissolved in hydrochloric acid, in acetic acid and in EDTA. Some were frozen in liquid nitrogen and then unfrozen. 550 preparations and also 35' microsections and 40 surficial sections were made; the former were then preserved in the Canada balsam. The microflore found there is usually poorly preserved. Sporangia and fructifications of Fungi and Sphaeromorphidae are comparatively best preserved, while Cyanophyta are much worse. The Sphaeromorphida group is the most abundant one in genera and species. Species: Prostosphaeridium flexuosum T i m., Protosphaeridium laccatum Tim. according to B. W. Timofiejew (1966, 1969) are widely spread in Vendian and Riphaean (late Precambrian), but there are only few in the Cambrian. Others, such as: Protosphaeridium vermium Tim. , Pterosperomopsimorpha annulare T i m., Leiosphaeridium — type R. Pf lug, Synsphaeridium sorediforme T i m., are quoted by this author from Riphaean. Among Cyanophyta the genera: Cephalophytarion, Paleonacystis, Sphaerophycus parvum S с h., Catinella polymorpha — the form F. Pf lug, Miliaria implexa Pflug were described by J. W. Schopf (1968), J. W. Schopf et J. M. Blacic (1969), H. Pflug (1966) from the Upper Proterozoic of Australia and the Rocky Mountains in North America. The genera: Gunflintia grandis Bargh., Gunflintia minuta and Eosphaera come from the Lower Proterozoic of Canada (E. S. Barghorn et S. A. Tyler 1965). Also the genera Fibularix, Scintilla and Tormentella were described by H. Pflug from the Upper Proterozoic. The genus Belaiaella, described by P. N. Kołosow (1970), as well as Phycomycetes, presented by B. W. Timofiejew (1969), come from the Riphaean of Siberia. Ascomycetes have not been quoted from the Pre-Cambrian, so far. Having analysed the stratigraphie range of the described genera of microflora (vide specification of the described microflora), the Archaean age of limestones, suggested by A. Lepla (1910), should be thus excluded. Assemblages characteristic of the Cambrian are also absent here, which would not confirm J. Gierwielaniec’ s suggestion (1957, 1965) of the possible Cambrian age of limestones, either. The Upper Proterozoic age seems to be the most reasonable one, which is indicated by the prevalence of genera and species of the microflora. At the present stage of investigations it is difficult to decide whether other crystalline limestones in this area are of the same age as the ones described from the Duszniki region, or whether they are younger or older. Further studies will allow a solution of this problem.