Informace o publikaci
The lost Jurassic world: New collection of fossils from the lost Jurassic locality Brno – Švédské šance, Bohemian Massif (Czechia
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| Rok publikování | 2024 |
| Druh | Konferenční abstrakty |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | Brno – Švédské šance is a classical locality of the Brno Carbonate Platform, formed during the Late Jurassic on the northern margin of the Tethys Ocean. This locality was studied since the end of the 19th century after the opening of several small quarries exposing the uppermost layers of approximately 130 m thick succession of mainly Oxfordian carbonate rocks (Eliáš 1981). About 130 species, including 23 new, were found during the times of active quarrying (Uhlig 1881; Oppenheimer 1907). Since 1949, the quarries were backfilled by industrial waste and rubbish. In 2022, the top of southern-quarry wall was exposed during excavations of foundations for industrial buildings. At this time, we visited the locality to collect as many fossils as possible. We have also localized part of Oppenheimer’s (1907) collection, including 11 holotypes of ammonites, at the Geological Institute, University of Vienna. Here we provide the first results of our investigation. Microfacially, pelbiomicrites and biopelmicrites prevail over biomicrites and pelintrabiomicrites. Packstones are more frequent that wackestones and microbial boundstones. Nests of spiculites and abundant bioclasts (crinoids, foraminifers, echinoids, serpulids, ostracods, bivalves, stromatoporoids, gastropods, Crescentiella moronensis) can be seen in thin sections. Bryozoans are quite frequent in the upper part of the quarry. Foraminifer assemblages from acid residues are dominated by spirillinids – mainly Spirillina kuebleri and S. concava – due their dissolution resistance (see also Bubík 2010). Thin sections shows higher diversity, with Falsogaudryinella uvigeriniformis, Protomarssonella, Paleogaudryina, Coscinoconus alpinus, Trocholina transversarii, Bullopora tuberculata, miliolids (Istriloculina, Quinqueloculina, Ophthalmidium, Vinelloidea, Earlandia, Cornuspira), nodosariids (Lenticulina, Astacolus, Pyramidulina), Rumanolina feifeli, Hoeglundina, etc. Exposed limestones were relatively poor in macrofossils. The most fossiliferous layers in the past were situated in the northern quarries (Oppenheimer 1907). Nevertheless, the southern quarry yielded tens of terebratulid and rhynchonellid brachiopods including Somalirhynchia moravica, various bivalves (Ctenostreon cf. proboscideum, Goniomya trapezina, Pleuromya cf. uniformis, Pteria, ?Entolium), gastropods (Pleurotomaria, Pseudomelania), echinoid spines (Rhabdocidaris cf. orbignyana), and abundant crinoids (Millericrinida, Isocrinida). Less common were sponges, serpulids, belemnites (Hibolites cf. semihastatus), and ammonites (one cast of Microbiplices sp.). Biostratigraphically most valuable is the collection of Oppenheimer (1907). The ammonites previously regarded as Perisphinctes are in fact representatives of Microbiplices (Andrzej Wierzbowski, personal communication). Based on ribbing, they correspond to the early species from the lower Hypselum Zone. Oppenheimer (1907) also figured several specimens of Epipeltoceras bimammatum, the index species of the Bimammatum Zone. Therefore, the age of the locality probably corresponds to the Oxfordian-Kimmeridgian transition (Hypselum-Bimammatum zones) which is in accordance with the numerous brachiopods S. moravica (Uhlig 1881), which are known from both of these ammonite zones. |
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