Uwagi o sedymentacji detrytycznych osadów sarmatu na obrzeżeniu Gór Świetkorzyskich

Abstract

REMARKS ON THE SEDIMENTATION OF SARMATIAN DETRITAL DEPOSITS IN THE MARGINAL AREA OF THE ŚWIĘTOKRZYSKIE MOUNTAINSSummaryAmong the sedimentary structures which occur in the marine detrital limestones of Saxmatian age in the marginal area of the Świętokrzyskie Mountains, cross-bedding seems to be most frequently found. At places, this is a large-scale cross-bedding as for example between Szydłów and Rybnica (Fig. 1). The stratigraphy of these deposits is discussed, among others by K. Kowalewski (1958), W. Krach (1962, 1967), K. Pawłowska (1965a) and S. Pawłowski (1965).In the case of the large-scale cross-bedding the thickness of the cross-bedded sedimentary, unit, measured from the underlying horizontally stratified limestones, may reach up to 12–13 m, and its length measured along the direction of transportation – 650 m. In a perpendicular  direction the same unit may stretch at a distance from 1.8 to 3.5 km. For the most part, the cross-bedding laminae are inclined at an angle of about 20–30°, ranging from a dozen to 35°. At places, landslides are found, too. Frequently, the upper part of the sedimentary unit is cut off, and covered with horizontally bedded limestone series. The limestones are characterized by a very slight change in direction of cross-bedding, as proved by the very high consistency ratio (P. E. Potter, F. J. Pettijohn, 1963) that amounts mainly to 91–97, exceptionally lass (67–85). Most probably, their sedimentation was quiet. On the boundary of the deep zone, probably at the edge of a submarine terrace the off-shore currents have laid down calcareous detritus, thus beginning the large-scale cross-bedding. According to A. V. Jopling (l955), a slightly tangential bottom contact of the cross-bedding laminae points to a mean velocity of currents, or to a mean current depth – basin depth ratio. These limestones were formed probably nearby, or somewhat below the wave base. From the view point of sedimentary environment, they mostly resemble the Upper Cretaceous sandstones of the Stołowe Mts. in these area of Middle Sudetes (T. Jerzykiewicz, 1966a, l006b).The cross-bedding observed to appear in the other occurrence areas of the Sarmatian detrital deposits, in organodetrital limestones with various sand contents and in sands and gravels, generally show a lesser thickness of the sedimentary units, as well as their smaller range, and the lower inclinations, of the laminae.On the other hand, the cross-bedding directions are here more changing, and, in consequence of this, the consistency rations are lower, amounting to 49–72, at places even 31–45. These deposits were formed in a considerably shallower and differentiated environment; where changes in wind direction may cause considerable changes in current directions. The cross-bedding (about 2000 measurements) found to occur in the central part of the area considered, points to transportation of clastic material from north, and in the western and eastern parts – from north-west.