Anisian Dasycladales from Upper Silesia and adjacent regions

Abstract

Anisian Dasycladales (calcareous algae) from the Diplopora Dolomite of the Upper Silesia and adjacent regions of S Poland are revised. All previously reported taxa are critically reviewed and illustrated. New paleontological samples were collected from 74 outcrops and from 45 boreholes. The abundant material includes both specimens visible on fractured rock surfaces and thin-sectioned ones; 24 species of Dasycladales are identified, including three new species: Oligoporella chrzanowensis n.sp., Physoporella polonoandalusica n.sp., and Salpingoporella krupkaensis n.sp. Best-preserved specimens are illustrated in 39 plates. The identified species were compared with Alpine and Carpathian forms of stratigraphic importance. Six Dasycladalean local horizons are defined. The Pelsonian-Illyrian boundary occurs in the middle part of the Diplopora Dolomite. Its uppermost part, despite the presence of Diplopora annulata, belongs to the Illyrian, not to the Fassanian, as also corroborated by conodont correlations. The peculiar state of preservation (internal moulds and double tubes) is discussed; it is due to early syngenetic dolomitisation. The palaeoenvironment of the algae is determined as sublittoral. Dasycladales flourished upon a peri-Tethyan carbonate platform, widely connected with the Alpine-Carpathian seas. Five palaeoecological assemblages are recognized, differing in their bathymetric and turbulence conditions, and living in marine shoals and shallow basins separating them. The Upper Silesian platform was separated from the hypersaline Germanic Basin of the Middle Muschelkalk by banks and oolite and bioclastic barriers, blocking dispersal of marine biota. A wide connection existed with the Alpine-Carpathian seas, allowing immigration of High-Tatric, Križna and even South Alpine flora to the Upper Silesian Carbonate Platform.