Wstępne badania mikroflorystyczne osadów sinianui kambru z obszaru Białowieży

Abstract

PRELIMINARY MICROFLORISTIC EXAMINATIONS OF THE SINIAN AND CAMBRIAN DEPOSITS FROM THE BIAŁOWIEŻA AREASummaryThe present paper deals with the results wfu1lh of miocrofloristic analysis of the Sinian and Cambrian deposits found in the bore holes Krzyże 4, Podborowisko 1 and Iwanki-Rohozy 3. Determination of microflora was based here  on the morphographic  system introduced by B. V.Timofieyev (1959) and S. N. Naumova (1960). Characterizing the individual genera, B. V. Timofieyevpointed to the reradiate mark, as to one of diagnostic features here. However, the present author failed in observing this feature in the specimens examined. Since other structural features have coincidedwith the description presented by the research worker mentioned before, his terminology has been accepted. It has been stated that the microflora of the Sinian deposits scarcely represented, and as a rule, feebly preserved. The specimens encountered during examination reveal a very simple  morphological structure. According to B. V. Timofieyev (1959) the genera here determined represent long-lived forms. In the East-European platform they appear from Proterozoic to Lower Palaeozoic formations inclusive. According to J. Znosko (1965), the Lower Cambrian may be subdivided into the lower and the upper Baltic beds. In the bore holes discussed in this paper it is represented by the lower Baltic beds. In the miocrofloristic spectra of the lower Baltic beds, beside qualitative, also great quantitative changes have been observed. They have permitted to subdivide the beds under consideration into two parts: the lower part “a”, and the upper part “b”. In J.Znoskoopinion (1965), the deposits of Middle Cambrian age not have been preserved in the area considered. In the Upper Cambrian deposits, i.e. in the Sklupowo beds according toJ. Znosko (1965), the miocrofossils have been encountered in the bore hole Krzyże 4 only. Most of the species found in the bore hole occur also in the Lower Cambrian deposits. Exceptions make here two index species that, according to B. V. Timofieyev (1959) are characteristic of the Upper Cambrian. In addition, the representatives of the genus Tasmanites N e w t o n, 1875 have also been encountered in the Lower and Upper Cambrian deposits. The specimens are well preserved and considerably differ from the species know to occur in the deposits of younger age. The specimens found in the Lower Cambrian deposits have been called Tasmanitesbobrowskiin.sp. and those from the Upper Cambrian described as Tasmanitessp.FamiliaTasmanaceaeSommer 1956 Genus TasmanitesN e w t o n, 1875 Tasmanitesbobrowskiin.sp. (Table III, Figs. 23­–27; Table IV, Fig. 28)H o l o t y p u s: specimen shown on Table III, Fig. 23. D e r i v i a t i o n  n o m i n i s: afterthe name of Ass Prof. Dr J. Raniecka-Bobrawska, the scientific leader of the palaeontological researches carried on in the Geological Institute, Warsaw. L o c u s  t y p i c u s: Iwanki-Rohozy 3. S t rat u m  t y p i c u m: clay shales of the lower Baltic beds (Lower Cambrian). M a te r i a l: 36 whole specimens and 90 fragments. Di m e n s io n si n  m i c r o n s: diameter from 90 to 160 (mean diameter about 120) D i a g n o s i s: Outline round, or round-oval. Surface rugged, covered with pores irregularly disseminated. Diameter of pores from 0,6 to 0,8 m. In the optical section of the wall the pores are visible as small canals of similar breath.  Thickness of wallsamounts to l,7–4.7 De s c r i p t i o n. Shape spherical, one specimen bottle-shaped. Flat specimens crumpled into roll-shaped and semilunar folds, are most frequently round. Pylome and suture are not observed, the latter being however, visible onthe representatives of this genus in younger deposits, e.g. on Tasmanitesbalticus E i s. described from Ordovician (A. Eisenack, 1963). Colour light yellow to amber-brown. C o m p a r i s o n s. According to the description, designs and photographsTasmanitesbobrowskiin.sp. resemblesTasmanitesmourai S o m mer occurring in the Barreirinha deposits (Brasil) that correspond to the Middle Devonian (F. W. Sommer, 1956) differeing, however, in size. As reported by Sommer,Tasmanitesmouraiis 370–490 m in diameter, thusTasmanitesbobrowskiin.sp. from the Lower Cambrian is about 3,5 times smaller. It differs from the species occurring in the Ordovician deposits of Estonia, described by A. Eisenack(1958, 1963), not only in having smaller size, but also in a considerably thinner wall, and is characterized by the absence of pylome. T a k s o n o m y. Systematic position of these interesting representative of microflora has been variously interpreted. First they were thought by Dawson (1871), to represent spores (fide D. Wall, 1962). As stated by A. Eisenack(1963), they were described by Barrand as trilobite eggs, by Kraft as graptolite eggs, and asalgae of unknown systematic position, similarly, as it was done by F. W.Sommer (l956). According to the recent data (D. Wall, 1962; A. Eisenack, 1963), the genus Tasmanites is referred to algae. D. Wall is of an  opinion that great similarity exists between the form Tasmanites sp. and the present-day representative of the marine Chlorophyceae (Pachysphaerapelagica O s t e n f e l d). This author suggests to refer the genusTasmanites sp. tothe fossil green algae (Chlorophyceae). Of similar opinion are also Ch. Dovnie, W. R. Evitt and W. A. S. Sarjeant (1963), who refer the genusTasmanites to the Chlorophyceae. Occurrence. Bore holes Iwanki-Rohozy 3, and Podborowisko 1, Lower Cambrian. Tasmanitessp. (Table IV, Figs. 29a, b, 30a, b) M a te r i a l: 4 whole specimens and 9 fragments. Di m e n s io n si n  m i c r o n s: diameter from 93,6 to 180 De s c r i p t i o n. Outline oval, or round. The whole surface of the specimen covered with regularly disseminated holes hores, the diameters , of which amount to 1,2–1,5m. Thickness of walls from 1,9 to 3,4 m. The specimens are flat and crumpled into small folds. Colour red-brown. C o m p a r i s o n s.Tasmanites sp. differs from Tasmanitesbobrowskiin.sp. in having thicker walls and greater and more regularly distributed pores. Probably, it is a representative of a new species, however, too little material is available at present to make final determinations. Occurrence. Bore hole Krzyże 4, Upper Cambrian deposits.