Konodonty z poziomu amorphognathoides (sylur) wschodniej części obniżenia podlaskiego

Abstract

W oparciu o stratygraficzno-paleontologiczną analizę konodontów z otworów Sobótka IG 1, Rajsk 4 i Krzyże 4 udokumentowano obecność ekwiwalentów biostratygraficznego poziomu amorphognathoides, który skorelowany jest z dolnym wenlokiem a, być może, i z najwyższą częścią landoweru.CONODONTS OF THE AMORPHOGNATHOlDES ZONE (SILURIAN) FROM EASTERN PART OF THE PODLASIE DEPRESSION The paper presents results of stratigraphic-paleootological studies based on the record of conodonts in marine Silurian rocks (mottled clay marls and gray-green marly and calcareous c1aystones with irregular intercalations of gray organodetrital limestones) from drillings (Fig. 1) made in eastern part of the Podlasie Depression (NE Poland). The findings of conodonts in the boreholes Krzyże 4 (464.0-467.0 m). Rajsk 4 (580.0-586.0 m), and Sobótka IG-1 (1515.0-548.8 m) appeared most important from the point of view of stratigraphy as they made it possible to identify a conodont assemblage typical of the amorphognathoides zone ('? uppermost Llandoverian - Lower Wenlock). Samples coming from the above listed depth interval yielded very numerous multielement species Carniodus carnulus Walliser, Pterospathodus amorphognarhoides Walliser. and Pterosphathodus pennatus procerus (Walliser). i.e. index taxa of the amorphognathoides zone (Fig. 2). Besides the above mentioned conodonts. the association also comprised very numerous conodonts of the single cone type, belonging to the genera Acodus, Distacodus, Drepanodus, and Panderodus, as well as specimens with more complex morphology, belonging to the genera Ligonodina, ? Distomodus, Neoprioniodus, Ozarkodina, Pseudooneotodus, and Trichonodella (Table 1). The conadont assemblage found in core material from the borehole Proniewicze IG 1 appears unuseful for biostratigraphic purposes as it comprises almost exclusively canodonts of the simple cone type, characterized by wide stratigraphic ranges.