Małżoraczki z górnego syluru Polski

Abstract

OSTRACODS OF THE UPPER SILURIAN IN POLANDSummaryUpper Silurian deposits have been encountered bore hoes: Lębork, Wejherowo and Chłapowo, situated in the Peri-Baltic area. The age of the deposits has been established to be Ludlovian. As far as their lithology is concerned, the deposits are represented by claystones with intercalations and lenses of limestones, or by politic, subordinately calcareous claystones with marly-calcareous intercalations. A micropalaeontological analysis points to the complete lack of foraminifers,and to the presence of numerous ostracods of the following families: Aechminidae, Primitiopsidae, Craspedobolbinidae, Beyrichiidae, Kloedenellidae and Cavellinidae. On ostracods the age of the deposits has been determined as Ludlovian, however, no finer ostracods zones have been distinguished. Smaller thickness of these beds prevented the author from investigating the whole extents of the occurrence areas of the species. In the region of bore hole Lębork, the lower occurrence boundary of certain ostracods species may by connected with the change of biofacies, since a pelecypod-brachiopod biofacies occurs at the upper parts of this section, and a graptolite biofacies may be found at its lower parts. The fauna assemblage distinguished in the bore hole here considered resembles the ostracods assemblage known to occur inside the Silurian erratic found in the areas of Sweden, Poland and North-west Germany. The assemblage is also similar to that described by A. Martinsson (1964) from the bore hole Łeba 1. The age of the deposits encountered by this bore hole has been variously interpreted by variously scientists; this makes any detailed correlation with the deposits pierced by the discussed bore holes impossible. The presence of a rich ostarcod fauna found in drill cores of all the bore holes under consideration seems to prove the hypothesis by A. Martinsson (1964) that a characteristic zone in the Baltic region marked in the Ludlovian deposits by ostracods.