Warstwy buhłowskie i ich pozycja stratygraficzna

Abstract

BUHLOV BEDS AND THEIR STRATIGRAPHICAL POSITION

Summary

Since the times of V. Laskarev and N. Sokolov the Buhlov Beds have been an object of intense discussions. Both mixed Tortonian – Sarmatian fauna and position between the Tortonian and Sarmatian stages were responsible for the difficulties in drawing the boundary between these stages, as well as, between the Middle and Upper Miocene. The Buhlov Beds were referred by V. Laskarev to Tortonian and compared with the Konka Beds. The appearance of the Sarmatian fauna was interpreted by him by palaeogeographical relations and by increasing fresh-water amount due to river-water inflow. In the later studies the relations of these formations to the neighbouring areas were investigated, and as a result of this, various formations in which mixed Tortonian - Sarmatian fauna was found, were referred to the Buhlov Beds. It should, however, be stressed here that one of the most important species Venus konkensis (= V. sobieskii), characteristic of the Buhlov Beds, has not been found in the formations studied. The problem got more complicated after introduction of new notions and range in the Buhlov Beds. According to O. S. Vjalov, L. N. Kudryn distinguished in these beds the lower part called the Wyszogród Beds, and referred this part to Tortonian, the upper part in turn – to Sarmatian. To the Buhlov Beds, Vjalov and Grishkievitsh referred only the middle part of these deposits (the so-called Beds “G”), determining it asTortonian, end the upper part (the so-called Beds “D”) - as Sarmatian. The author of the present paper joins an opinion that the Buhlov Beds should be referred to Sarmatian (Beds “G” and “D”), since already in the Beds “G” new fauna appears, characteristic of the Sarmatian. The author presents the way of formation of the Buhlov Beds as follows:

1 - regression of Tortonian in Europe and depositions of Wyszogród Beds and Sartagan Beds in the Ukraine,

2 - new oscillation of basins in the Ukraine, destruction of the substratum, and sedimentation of deposits of Buhlov and Konka Beds,

3 - detachment of the basin from the Mediterranean Sea, partly increase in fresh-water contents in bays and appearance of the Sarmatian forms as relics of living still in the Tshokrak basin and developing under new environmental conditions,

4 - new oscillation in the Upper Buhlovian, destructing the soft deposits of the substratum, and changing into the transgression of the Lower Sarmatian sea sensu strict

In Poland, the Buhlov Beds were thought to be represented by Syndesmya Beds within the Świetkorzyskie Mts. margin. These were referred to Tortonian or Sarmatian. In the Carpathian fore-deep to these beds corresponds the lower part of the so-called Krakowiec clays that uniterruptedly pass into the upper beds of Lower Sarmatian age sensu stricto. In the area of the Lublin Roztocze, the lower part of the detrital limestones, called Sarmatian limestones, have recently been referred to the Buhlov Beds, too.