Acta Palaeontologica Polonica

Givetian an d Frasnian calcareous microbiotas of the Holy Cross Mountains

Grzegorz Racki and Janina Soboń-Podgórska

Acta Palaeontologica Polonica 37 (2-4), 1992: 255-289

Each developmental phase of the Givetian to Frasnian carbonate complex of the southern Holy Cross Mts is marked by distinctive calcareous microbiota. The Stringocephalus bank deposits contain a very rich, well-preserved microproblematica (of chiefly? algal origin) dominated by calcispheroids, and many calcified cyanobacteria and green algae with filamentous Bevocastria; tubiform Devonoscale , a nd charophyte Trochiliscus. In the late Givetian  biostromal complex more sparse microfossil associations occur, with the exception of locally abundant semitextulariid foraminifera (mainly Nanicella) and tubiform dasyclad(?) Jansaella. Also in the Frasnian back-reef facies, only limited and poorly preserved calcispheroids are identified. Contrarily, reef- and fore-reef microbiotas were present in great profusion. Microbial mats (including calcified cyanobacteria Renalcis and Sphaerocodiwn), associated with locally frequent solenoporids and multichambered foraminifera (Nanicella, also many nodosariids in the later Frasnian) played a significant deposition al role and evidence progressive shoaling conditions within the Dyminy reef-complex.

Key words: alga, foraminifera, microproblematica, Devonian, Poland.


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