Tility wschodniej Polski

Borys Areń



Tillite-like formations or those resembling fanglomerates characterized by an uncertain genesis have for the first time been encountered in Poland when drilling at Wisznice, immediately above the crystalline basement, and under the complex of effusive and pyroclastic rocks. This complex is approximate to one series of the Upper Proterozoic that corresponds to the Wolhynia series according to the Soviet nomenclature, and partly to the Scandinavian sparagmites from Moelv. This series is called the Wisznice series or the Sławatycze series. As a result of numerous drillings made in the eastern area of Poland, other similar formations have been ascertained to occur above the crystalline basement. Distribution of these finds is, at present, restricted to two areas: 1 - SE of Białystok - Zabłudów and Rajsk, and 2 - NW of Włodawa - Wisznice and Kaplonosy. Due to the more important exposures of tillites within the Białystok area, a proposal is suggested to give them the name Białystok tillite formation. It appears that in the areas, where no basalt cover exists-tillites are absent, since they were not "preserved" by effusive rocks, and underwent erosion. Several basalt and conglomerate intercalations have been ascertained to occur in the area of Białystok, but it is not known, whether they belong to tillites. The tillites consist of pebbles of various shapes and sizes of different rocks. Basalts and porphyries predominate. Granodiorites and gneisses occur in lesser amounts. Cementing material consists of tuffs. The pebbles are fairly well rounded, but sharp-edged fragments and facetted pebbles are also encountered. Flat-iron-shaped fragments, having truncated base or characterized by three cut walls have been encountered as well. In addition, pebbles with concave walls are found, too. The surface of the porphyry pebbles is rough spongy. All the features mentioned above should prove the glacial origin of the tillites. The arrangement of the pebbles in the cementing material is in general contiguous, but loose interstices between the pebbles are also encountered. Within the Włodawa area, the tillite-like formations are stratified and are probably older in age than the tillites of the Białystok region.

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