Exceptional Preservation of Molluscs in the Buckhorn Asphalt
Seuß B, Nützel A, Schulbert C (2007)
Publication Language: English
Publication Type: Conference contribution, Abstract of a poster
Publication year: 2007
Event location: Antwerpen
Abstract
The Late Carboniferous (Desmoinesian, approx. 306 m years) sediments of the Buckhorn Asphalt Quarry (Oklahoma, USA) contain the best preserved Palaeozoic mollusc fauna world wide. Molluscs are commonly preserved in original aragonite including shell microstructures, though aragonite is normally dissolved or recrystallised shortly after deposition. Even larval shells and colour patterns are preserved. The good preservation of fossils was caused by Ordovician oil which intruded into the sediments simultaneously to or shortly after deposition, sealing pore space and preventing recrystallisation via circulating pore waters. The oil then transformed into asphalt loosing its volatiles. The fauna of the Buckhorn Asphalt is dominated by mollusc species, especially by cephalopods and small gastropods. For the purpose of inferring the depositional environment and Palaeoecology, thin sections were prepared from samples of all main lithologies. Asphaltic rocks were dissolved in a Soxhlet apparatus using methylene chloride as solvent (asphalt content is up to 20%). The dissolved samples were sieved (2 mm, 500 µm, 125 µm) and picked. Fossils, especially small gastropods were documented with SEM- and light microscope pictures. Bioerosion in the Buckhorn fossils is common and could be proved using SEM-photographs of fossils and casts, as well as with thin sections. At least 50 gastropod species, two coiled and three orthocone nautiloids have been documented, however brachiopods and bivalves are rare. The rich marine fauna is furthermore represented by ostracods, foraminifers, echinoderms, and bryozoans. Vertebrate remains like fish teeth are rare. First results suggest that most fossils lived in shallow water as is indicated by a diverse assemblage of bioeroders within the mollusc shells as well as by the presence of large land plant remains. The fossil material is mixed with siliciclastic sediment which is conglomeratic sometimes, and was transported over a relatively steep slope or in channels.
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Germany (DE)How to cite
APA:
Seuß, B., Nützel, A., & Schulbert, C. (2007). Exceptional Preservation of Molluscs in the Buckhorn Asphalt. Poster presentation at World Congress of Malacology, Antwerpen.
MLA:
Seuß, Barbara, Alexander Nützel, and Christian Schulbert. "Exceptional Preservation of Molluscs in the Buckhorn Asphalt." Presented at World Congress of Malacology, Antwerpen 2007.
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