Stratygrafia oksfordu centralnej Lubelszczyzny w powiązaniu z profilowaniem geofizycznym otworów wiertniczych

Abstract

OXFORDIAN STRATIGBAPHY OF THE CENTRAL LUBLIN REGION IN THE LIGHT OF GEOPHYSICAL LOGGING IN BORE BOLE

Summary

Good results obtained from geophysical surveys in the Jurassic deposits of the Lublin Region allow us to distinguish, in the logging picture of the Upper Jurassic of this area, a series of logging complexes determined lithologically and stratigraphically.

New geophysic-gological material makes possible, at present, to subdivide the complex A in detail (J. Królicka, 1966), only on the basis of logging curves. In this complex, which corresponds to the deposits of Oxfordian age, two smaller units may be distinguished: complex A_II - that corresponds to the Upper Oxfordian deposits, and complex A_I - that may be related to the Middle and Lower Oxfordian deposits.
The correlation of the bore holes made in the Lublin Region demonstrates that the complex A_II may be found in the whole area considered, whereas the complex A_I occurs, as a whole, only in the region of Opole Lubelskie, Pionki, and within the North Lublin Region. In the central area of the Lublin Region only the upper member of this complex may be encountered (Fig. 2).
Lithologic-stratigraphical analysis of the individual complexes illustrates that in the central area of the Lublin Region (Bystrzyca, Niedrzewica. Fig. 3), Middle Jurassic deposits, Lower Oxfordian deposits and lower part of Middle Oxfordian deposits are absent. Jurassic sedimentation begins here with the formations of the upper part of the Middle Oxfordian (Fig. 4). This does not concern the area of Lublin (bore hole Lublin IG 1, bore hole Świdnik IG 1), where the lower part of the logging complex A_I occurs. Its arenaceous nature points to a relation with the region of Bystrzyca, where uplifting movements took place at the Middle Jurassic and Lower Oxfordian times. These are responsible for the erosion of the Jurassic basement, in this case the erosion of Carboniferous sandstones and siltstones which were sources of arenaceous material for the sediments of the Lower Oxfordian, pierced in bore holes Lublin IG 1 and Świdnik IG 1.