Tektonika Kujaw

Abstract

TECTONICS OF THE KUJAWY REGIONSummaryThe Kujawy swell is part of a larger tectonic unit called also the Middle-Polish swell. It consist of the north-western, i.e. the Pomeranian part, the central i.e. the Kujawian part, and the south-eastern, i.e. the Gielniów–Tomaszów part. The Middle-Polish swell discloses in its axial portion a Jurassic, almost uninterrupted core. The swell is built up of the Zechstein-Mesozoic complexes only. Within the south-eastern area the Middle-Polish swell joins the Mesozoic cover of the Paleozoic core of the Świętokrzyskie Mts.The Middle-Polish swell developed within the zone of Teisseyre's line, at the contact of the pre-Cambrian and Palaeozoic platforms. To the east and north-east the swell and the adjacent depressions are surrounded by a stiff, strongly elewated crystalline basement, and in the south and south-west both the swell and the adjacent trough are restricted by the front of the buried Variscids. Under such geotectonic conditions the area here considered must have been distinguished by a tendency to an intense and differentiated subsidence resulting in the character and rate of the Permo-Mesozoic sedimentation. The Kujawy area was affected by the post-Variscan tectonics, most intensely the Late Mesozoic one, accompanied by salt tectonics, phenomena.The zone of the Teisseyre's line represents boundary of both palaeogeographic and tectonic significance. Its foundation is as related to the pre-Cambrian time. It separated areas of differenced sedimentation and of various tectonic development. The zone of the Teisseyre's line made, in the area of Poland, the eastern and north-eastern boundary of the Caledonian geosyncline. The tectonic zone of the Teisseyre's line was posthumously active till the dose of the Cretaceous period. In this zone a series of dislocations were formed, mainly concordant with its direction and strongly influencig both the sedimentation and facies distribution in the Mesozoic time.The greatest; thicknesses of the Zechstein-Jurassic deposits we known from the zone of the developing Middle-Polish swell, and those of the Jurassic-Cretaceous deposits – within its western periphery, i.e. at the boundary of the coming troughs and swell. Thus the accumulation of the deposit took place in a zone restricted in the north-east; and east by the Teisseyre's line, and the south-west and west – by dislocations along which the limb of the Middle-Polish swell and the adjacent troughs developed.In the Zechstein-Cretaceous time the subsidence within the Kujawy swell was not uniform. It results, from the analysis of the thicknesses of the sedimentary complexes (Table 1) that the areas of the future Kujawy swell was subdivided into three parallel zones: middle, i.e. Kutno zone, northern, i.e. Gniewkowo zone, and southern, i.e. Rawa zone. Most intense subsidence was within the central part, i.e. in the Kutno zone (Figs. 1 and 2). The existence of these three areas was conditioned by the discontinuity zones found in the deep basement. These are shown in Figs.·1 and 2.To the Kutno subsidence area are related phenomena of the highly intense salt of tectonics. Outside of this central area a transition zone exists, also restricted with some fault zones. where salt tectonics is expressed in the form of salt swells and pillows only.The zone of the Teisseyre's tectonic line consists of a lot of parallel faults that posthumously were developed derivatives of the deeper and older foudation of this line. These too, strongly affected the sedimentation in the Zechstein time and the whole Mesozoic. Within the zone of the Teisseyre's tectonic line, and east of this line, a block-placanticlinal character of tectonics developed, resulting in a gradual extinction of the phenomena of salt tectonics.