Llandovery microfossils and microfacies of the Hýskov section, Prague Basin

Abstract

<jats:title>Abstract</jats:title> <jats:p>The lower Silurian strata of the Prague Basin, as well as in many other regions, are primarily represented by black shales, with limited to no record of benthic life. In this paper, we describe an exceptional late Aeronian volcanic-carbonate succession from the Hýskov locality near Beroun, which contains a diverse and well-preserved fossil assemblage and specific microfacies features. The studied section is mostly represented by well-washed, poorly sorted skeletal grainstones, rudstones and floatstones along with volcaniclastic material. The environment is interpreted as agitated, above storm wave base, and with rapid sedimentation and burial. The collection of acid-resistant microfossils includes abundant scolecodonts, conodonts and chitinozoans, of which only the chitinozoans have previously been studied. The scolecodonts recovered represent at least 14 polychaete genera and 20 species. The fauna bears a great similarity to the early Silurian assemblages previously reported from Baltica, and some environmentally sensitive species allow constraining the assemblage to shallow-shelf settings. The recovered conodonts similarly show close affinities to Baltic faunas, and suggest a Rhuddanian – Aeronian age for the studied section. The chitinozoan assemblage, containing at least eight species, is dominated by <jats:italic>Conochitina</jats:italic>, and most likely belongs to the <jats:italic>C. alargada</jats:italic> Biozone.</jats:p>

Lingulates of the Monograptus belophorus Biozone (Motol Formation, Sheinwoodian, Wenlock) of the Barrandian area, Czech Republic: insight into remarkable lingulate brachiopod diversity in the Silurian

“…The episode of sea level fall in the late Aeronian (Loydell 1998, Frýda & Štorch 2014) first brought the diverse benthic biota into the basin, but only outside the Svatý Jan volcanic area where the Špičatý vrch locality is located. The rich fauna in volcaniccarbonate facies in the Hýskov area north of the Beroun is unique in the Llandovery in northern periGondwanan regions (Havlíček & Kříž 1973, Šnajdr 1978, Kraft 1982, Havlíček & Štorch 1990, Štorch 2001, Tonarová et al 2019.…”

Dendritic microborings in brachiopod shells from the Silurian of the Barrandian area, Czech Republic

“…The volcano-sedimentary sequence of the Želkovice Formation is represented by tectonically disturbed basalts with hyaloclastites that are followed by calcareous tuffites, tuffaceous limestones, tuffaceous and calcareous shales. The shales have yielded a rich fauna of late Aeronian age (Stimulograptus sedgwickii graptolite Biozone; Štorch 2001; Conochitina alargada chitinozoan Biozone, Tonarová et al 2019), with 13 graptolite species (Štorch 2001), 26 trilobite species (Šnajdr 1975, 1978), 30 brachiopod species (Havlíček 1977;Havlíček & Štorch 1990;Mergl 1999Mergl , 2001, 13 species of dendroid graptolites (Kraft 1982), 20 polychaete taxa (Tonarová et al 2019) and so far unrevised gastropods, corals and other invertebrate groups. Acritarchs, chitinozoans and co no donts were studied by Dufka (1990Dufka ( , 1992 and Tonarová et al (2019).…”

“…The shales have yielded a rich fauna of late Aeronian age (Stimulograptus sedgwickii graptolite Biozone; Štorch 2001; Conochitina alargada chitinozoan Biozone, Tonarová et al 2019), with 13 graptolite species (Štorch 2001), 26 trilobite species (Šnajdr 1975, 1978), 30 brachiopod species (Havlíček 1977;Havlíček & Štorch 1990;Mergl 1999Mergl , 2001, 13 species of dendroid graptolites (Kraft 1982), 20 polychaete taxa (Tonarová et al 2019) and so far unrevised gastropods, corals and other invertebrate groups. Acritarchs, chitinozoans and co no donts were studied by Dufka (1990Dufka ( , 1992 and Tonarová et al (2019). The depositional environment was described by Kříž (1991) and Tonarová et al (2019) and interpreted as well-ventilated, shallow water, agitated flats on effusive and volcanoclastic sediments of the Hýskov Volcanic Centre.…”

“…Acritarchs, chitinozoans and co no donts were studied by Dufka (1990Dufka ( , 1992 and Tonarová et al (2019). The depositional environment was described by Kříž (1991) and Tonarová et al (2019) and interpreted as well-ventilated, shallow water, agitated flats on effusive and volcanoclastic sediments of the Hýskov Volcanic Centre. The rich benthic shelly fauna observed here is unique in the Barrandian area, because in other localities of the Želkovice Formation only planktonic and/ or epiplanktonic forms are present.…”