O pochodzeniu materiału doggerskiego na wyniesieniu łukowsko-wisznickim

Abstract

ON THE PROVENANCE OF DOGGER MATRIAL IN THE ŁUKÓW-WISZNICE ELEVATION

Geological examinations undertaken within the recent two years in the Lublin and Podlasie area and, especially, penetration of the crystalline, substratum by 4 deep bore-holes (Łuków - 750 m., Radzyn -1670 m., Mielnik - 1600 m., Wisznice - 270 m.), yield the most actual data on the morphology of the crystalline substratum of this area.

According to B. Areń's interpretation we are dealing here with a distinct elevation of the substratum starting at Łuków and extending towards Wisznice and on Soviet territory, towards Ratno, with culminations observed at Łuków, Wisznice and Ratno.

On the basis of studies of the sedimentary cover of this region this elevation seems to have originated during the Palaeozoic and Older Mesozoic. The present-day morphology of the surface of the substratum developed probably after the Jurassic period. The course of sedimentation overlying the Łuków-Wisznice elevation is connected with an uplift of the substratum extending from southwest towards northeast, from a depth of 750 m. at Łuków to 270 m. at Wisznice. To this remarkable rise of the substratum observed at Wisznice must be ascribed the absence of the Carboniferous, Permian and Triassic deposits at the latter locality.

In the elevation mentioned, the Jurassic sedimentation commences with Dogger sediments, heterogeneously developed and showing differences in thicknesses in the eastern and western part of the elevation. In the Łuków bore-hole, these sediments are characterized by a facies of organodetrital, slightly arenaceous limestones. At Wisznice, these sediments are predominant predominantly arenaceous. Similar Jurassic deposits are known from the adjacent region of Western White Russia.

The character of the sediments appearing here, and numerous fragments of vulcanites, tuffs, tuffites and effusives, as well as fragments of crystalline rocks indicate a fairly close connection with both the substratum and the adjoining area not embraced by the Jurassic transgression. The detailed analysis of the fragments mentioned suggests that part of this material is connected with Eocambrian rocks while another part represents material of resedimentation the source of which are Cambrian rocks, mainly of the Waldai complex. This latter material reaches the Łuków region, situated fairly distant from the rim of the basin, only sporadically and singly, and in the shape of very small grains.

Sedimentation of the Oxfordian proceeded rather uniformly over the entire elevation, leaving in its wake calcareous deposits in a facies·of reef and reef-flank limestones, organodetrital and, sometimes, marly, partly silicified with flint nodules.

The Oxfordian sediments terminate the Jurassic sedimentation in the Wisznice culmination. At Łuków, Rauracian and Astartian sediments appear additionally.