The Tithonian Chitinoidellidae and other microfossils from Owadów–Brzezinki quarry (central Poland)

Tithonian (= “Middle Volgian”) carbonate rocks are exposed in Owadów-Brzezinki quarry 19 km southeast of Tomaszów Ma-zowiecki, central Poland. In the upper part of the Sławno Limestone Member, chitinoidellids have been identified in thin sections from three samples, only. Therefore, the documented part of the Chitinoidella Zone in Owadów-Brzezinki quarry is about 0.3 m thick. The identified chitinoidellid taxa suggest that this assemblage represents the Upper Tithonian Boneti Subzone. The Chitinoidella Zone occurs at the top of Unit I and correlates with the uppermost interval of the Zarajskensis Horizon (Matyja, Wierzbowski, 2016). Other microfossils identified in the Chitinoidella Zone consist of Saccocoma sp. and benthic foraminifera of the genus Planularia. Calcareous dinoflagellate cysts (Cadosina semiradiata semiradiata Wanner and C. cf. semiradiata semiradiata Wanner) occur above the chitinoidellid assemblage, in the strata corresponding to the Gerassimovi Subzone of the Virgatus Zone (Matyja, Wierzbowski, 2016). Calcareous nannofossils are extremely rare in the thin sections studied; only one small specimen was seen, identified as Rhombolithion minutum (Rood et al., 1971) Young et Bown 2014. In contrast, microbial filaments are frequently observed in the studied thin sections. Their shape and pattern are reminiscent of some recent Cyanobacteria of the order Nostocales, however the Tithonian microbial filaments are much thinner.