Utwory płasżczowiny podśląskiej w wierceniu Cieszyn 10

Abstract

DEPOSITS OF SUB-SILESIAN NAPPE IN BORE HOLE CIESZYN 10SummaryThe section of the Sub-Silesian nappe observed in bore hole Cieszyn 10, situated near Cieszyn, is of particular importance for the knowledge of the stratigraphy and of the tectonics of this unit. This is the only almost complete profile of the unit considered, observed in one bore hole. The detailed micropalaeontological examinations have demonstrated that the section almost entirely consists of various fragments and tectonic remnants of shale beds, different in age, arranged chaotically. The age of these beds is from Barremian to Oligocene, inclusive. The thickness of the tectonic remnants ranges from 0.1 to 9.7 metres, that of the tectonic, crushed and mixed formations, being from 1.0 to 7.3 metres. Among the Sub-Silesian formations, a tectonical detached block of the Lower Cieszyn shales of the Cieszyn nappe have been noted to occur in the section of bore hole Cieszyn 10 at a depth from 529.5 to 555.3 metres. Detailed micropalaeontological examinations of the beds of the detached block prove its Lower Tithonian – Berriasian age. This points to a fact that the member of the Cieszyn limestones is replaced with the facies of the Lower Cieszyn shales. Moreover, an inversion of beds found to occur in the detached block have been ascertained, as well. The almost complete core material taken from the Sub-Silesian nappe deposits in bore hole Cieszyn 10 proved the previous suggestions as to the tectonic character of the unit considered (K. Konior, 1959, 1960 a, b, c; A. Jednorowska, K. Konior, 1965). Chaotic fragments and tectonic remnants of beds, various in age, are characteristic feature of its structure. This fact is evidenced by the microfauna assemblages of the samples frequently taken even some centimetres apart, characterized by great stratigraphical differences. Under these conditions, an attempt at looking for any regularity within the ground and mixed plastic mass, which is represented here by the Sub-Silesian nappe deposits, seems to be doomed to fail. This unit is built up of specific debris, various in thickness. However, the debris are independent of the overlying units, as proved by its considerably thickness observed in the immediate neighbourhood of the massive Godula nappe (bore holes Ustroń 1 and Kęty 3), or even within this nappe (bore holes Andrychów 2 and Andrychów 4).