Upper Triassic freshwater oncoids from Silesia (southern Poland) and their microfossil biota

Talanda, MateuszUniv Warsaw, Fac Biol, Dept Paleobiol & Evolut, Biol & Chem Res Ctr, Zwirki & Wigury 101, PL-02089 Warsaw, Poland. (författare)

Oncoids are rare components of Keuper sediments across Europe. The exceptions are localities linked to the Upper Triassic "Wozniki Limestone" (formally Limestone Member from Wozniki) in Silesia, southern Poland. Numerous oncoids occur in breccia-like deposits in the Lipie Slaskie clay pit at Lisowice. The oncoid-bearing level is underlying by organic-rich carbonaceous mudstone and siltstone and covered by non-carbonaceous sandstone and grey wacke sandstone-mudstone heterolithic deposits. The oncoids are of various shapes and are built by agglutinated or skeletal stromatolites composed of a rhythmically grown dendroid micropeloidal framework. The agglutinated stromatolites are poor in microfabrics. The oncoids consist of a smooth or granular outer part and distinct core (carbonate, carbon-rich or phosphate), which may be a fossil (bivalve shell, wood fragment, charcoal piece, carbon-rich coprolite or hone fragment). Dark laminae of the cortex are carbonate-rich, whereas the light ones are silica-rich. They exhibit remains of bacterial/cyanobacterial filaments, as well as some rare and not well-discernible palynomorphs. Ostracods (cf. Darwinula sp.), small fragments of vertebrate bones (mainly fish remains), fragments of wood, plant cuticles and fragments of unionoid bivalves are associated with the oncoid accumulations. Thus, they may have been formed in a shallow freshwater environment and were buried by rapid flood events or mud runoff.

Bajdek, PiotrAleja Najswietszej Maryi Panny 20-20A, PL-42200 Czestochowa, Poland. (författare)
Niedzwiedzki, Grzegorz,1980-Uppsala universitet,Evolution och utvecklingsbiologi(Swepub:uu)grzni333 (författare)
Sulej, TomaszPolish Acad Sci, Inst Paleobiol, Twarda 51-55, PL-00818 Warsaw, Poland. (författare)
Univ Warsaw, Fac Biol, Dept Paleobiol & Evolut, Biol & Chem Res Ctr, Zwirki & Wigury 101, PL-02089 Warsaw, Poland.Aleja Najswietszej Maryi Panny 20-20A, PL-42200 Czestochowa, Poland. (creator_code:org_t)

Ingår i:Neues Jahrbuch für Geologie und Palaontologie - Abhandlungen: E SCHWEIZERBARTSCHE VERLAGSBUCHHANDLUNG284:1, s. 43-560077-7749

Av författaren/redakt...: Talanda, Mateusz; Bajdek, Piotr; Niedzwiedzki, Gr ...; Sulej, Tomasz

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