Rozwój sedymentacji dewonu w rejonie Tomaszowa Lubelskiego

Abstract

DEVELOPMENT OF DEVONIAN SEDIMENTATION IN THE AREA OF TOMASZÓW LUBELSKI

Summary

The bore hole at Tomaszów Lubelski is situated in the south-eastern part of the Lublin voivodship. Below the deposits, tentatively referred to Tournaisian, are found Devonian formations encountered in this bore hole at a depth of 1312.9 m. Here are found all three members of the Devonian, i.e. Lower, Middle and Upper (Table 1). On the basis of their carbonate contents, these deposits can be subdivided into three complexes. These complexes, which may easily be observed to occur in the section and on the diagram (Fig. 1), do not coincide with the stratigraphical subdivision. 1. The lower complex is of clastic nature, consisting of alternating quartzite sandstones and variegated siltstones and claystones. This complex may be subdivided into three members characterized by an increased sand content and by siltstone intercalations. The profile consists mainly of siltstone-clayey rocks. 2. The middle chemical-dolomite complex is characterized by the occurrence of dolomitic rocks and of anhydrite. In this complex two members have been distinguished: lower member of marly nature, and upper member that consists mainly of cavernous dolomites. Anhydrite occurs in the whole complex, its amount decreasing distinctly upwards. 3. In the upper organogenic-calcareous complex nodular limestones prevail. Fauna is here fairly abundant. The lower member of this complex still contains a great amount of dolomitic substance. In the middle member this substance occurs only locally, whereas in the upper one, the content of the dolomitic substance increases again. The complexes discussed in this paper are a logical effect of the consequent development of the Devonian basin: from the Old Red sedimentation, through a continental, strongly evaporating basin, to a shallow open sea. The shallowness of the sea is proved by numerous banks of coral limestones. Dolomite intercalations, that appear at the top of the upper complex, point to a new change in conditions that led to the sedimentation of the Tournaisian (perhaps Upper Famennian) dolomites, and finally caused a sedimentary gap in the Lower Carboniferous.