Stosunki tektoniczne w piaskowcu borysławskim w Borysławiu i zachodn. części Tustanowic

Józef Jakub Zieliński


Structural conditions in the Borysław Sandstone at Borysław and in western part of Tustanowice

In connection with the repressuring projects in Borysław Oil Field, worked out by Research Bureau of Petroleum Industry, selection of geological units and knowledge of their structural conditions have become a very important problem. The geological structure of Borysław oil field has been worked out by dr. Tołwiński and his collaborators in the „New Geological Atlas of Borysław“1). The present paper is a contribution to this „Atlas“ ; it deals with the Middle- and Northern part of the Borysław fold, where after the year 1930, several new wells were drilled and gives new ideas concerning transversal dislocations, dividing the bed into several structural units. Due to the lack of geological logs of majority of wells in this region the depth indications of gas- and oil-shows from the drilling logs have been taken into consideration and the correlation-sections of all wells were made in the scale of 1:1000. The comparison and analysis of these sections together with the geological data obtained from wells drilled after the Great War enabled the author to reconstruct the stratigraphie sections of individual wells. On this basis many geological cross-sections, transversal and longitudinal, the contour map of the top of the second Borysław sandstone and a plastic map have been made. This method allowed to reanalyse and adjust the data in a logic complex, may be simplified too much, but in general the outlines are probably satisfactorily true. The present report has to deal with the Borysław sandstone exclusively, as one of the most important oil-bearing reservoir of the Borysław oil-field. Borysław sandstone does not form an uniform bed, but is composed of two layers: first Borysław sandstone and se cond Borysław sandstone, interlaminated by brown-grayish shales. The thickness of the first sandstone and shales varies from several meters to 15 meters, the thickness of the second sandstone amounts to 10—14 meters, according to the local structural and sedimentary conditions. In the described region (fig. 2 and 5) the most important structural element forms the Culmination of Borysław. This element is bounded from the North by Frontal Zone, from the East by Eglon fault, and from the West by Ratoczyn fault. These faults have shifted the axis of the fold to the South and have initiated two new structural elements: that of Ratoczyn and the Central-Element. The Central Element is bounded on the Eastern side by a great dislocation, running along the line joining the well: Los Angelos—Milano 6, so called „Kamionka dislocation“, which caused an uplift of the transversal axis of the fold to the North and initiated a new structural element, namely the Culmination of Tustanowice. Culmination of Borysław rises to the height of 330 m below the sea level, that is relatively to the depth of 720 m, forming thus the greatest elevation of that horizon in this region. Further on (fig. 3) Culmination of Borysław is dipping very steeply up to the line of the wells: Boxall—Szczur 1—Kanada (contour line 700) and after that gradually forms the gentle terrace of the region Silva Plana—Konrad—Apollo, and almost flat zone of the mines Jerzy, Nafta and Wanda. The Western part of the element is cut off by the secondary dislocation of Dąbrowa—Ratoczyn fault, vanishing towards the South-West. The Dąbrowa-Ratoczyn fault forms a kind of step to the proper Ratoczyn fault (cross-section III fig. 5), which is shifting back the frontal p a rt of the fold about 600 m towards the South and submerges the Western p a rt of the fold about 100— 150 metres. To the East we see (fig. 2) almost classical, gentle dipping of the Culmination of Borysław, cut down by the fault called Eglon. The Central Element forms a sort of „Graben“ (fig. 5) between the Culmination of Borysław and that of Tustano wice, and is dipping in its highest p art normally to the South- West. The dislocation cutting down that element into two blocks, Eastern and Western, is well marked, beginning from the contour line 600. This dislocation, called by Hempel „Kozak“ fault, is characterized by its zone bereaved of the Borysław sandstone, proved by the wells: Union 3, Pontresina 5, Silva Plana 21, Aleksander 1 and Bernard 2. That zone is due to the shifting down the Western pa rt of the fault along the fault plane inclined to the South-West, so that the above mentioned wells after having gone through the Menilitic series have entered immediately into the Popiele beds. The height of the fault is about 200 m and inclination of the fault plane about 70°. There are great differences between Eastern.and Western block of the Central Element, as far as their form is concerned. The Western block is related very closely to the adjoining Culmination of Borysław, but it is not so regular as the adjoining p a rt of the well Silva Plana, Konrad, probably due to its location between two faults. At the top of the Eastern block we notice almost horizontal dips; more slopping dips are observed after crossing the contour 680, and simultaneously the direction of the contour lines is changing from the North-East to the South-West under the influence of the „Kozak“ fault. The dislocation of Kamionka, marked very strongly on the frontal pa rt of the fold, is shifting the Culmination of Tustanowice about 600 m towards the North-East. The difference of the level of these two elements is marked quite clearly in the section: Glinik 35 — Friedrich and Glinik 36 — Meta 2. Observing the continuation of the „Kamionka dislocation“ towards the South-West, we see (fig. 2) that its height decreases very soon, and in the vicinity of the well: Tłoka-Bank 12, we notice the intersection of shifted surfaces, and then the Central Element is still rising, giving the mean difference of the levels about 20 metres. The outline of the frontal p a rt of the Culmination of Tustanowice has been determined (fig. 2 and 4) in the last few years by the wells: Magda, Margot 4, and Herta 3. The top of the Culmination, situated North from the well „Lucky Star 2“ is elevated about 500 m b. s. 1. and then is dipping towards the transversal depression of Truskawiec. The cross-section (fig. 4) shows a regular gentle dip of the strata up to the secondary u p lift of the Blochówka mine rising to the height of about 40 m above the surrounding. The described part of the Culmination of Tustanowice is ending the present report; the middle and eastern part of Tustanowice have been worked out by Dr. O. V. Wyszyński2).
1) Nouvel Atlas Géologique de Borysław, Bull. 19, Station Géologique Karpatique. 1950.
2) Dr. O. V. Wyszyński: La corrélation des horizons pétrolifères dans le grès de Borysław à Tustanowice—l’Est. Service Géol. Karpatique. Bull. No. 24, Borysław 1934.

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