Palaeoecology and palaeogeography of Late Ordovician (Katian–Hirnantian) cephalopods of the Boda Limestone, Siljan district, Sweden
2014 (English)In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 47, no 1, 15-30 p.Article in journal (Refereed) Published
The carbonates associated with the Late Ordovician (Katian–Hirnantian) Boda mounds of the Siljan district, Sweden, contain a rich cephalopod fauna. Cephalopodsare rare in the micritic stromatactis facies of the Katian Boda Core Member, but are concentrated together with other molluscs and trilobites in synsedimentary fillings of caves and crevices of the lithified mound limestone. More than 60 cephalopod species are known from these fillings. The assemblage is dominated in richness and abundance by small orthoconic proteoceratids of the genus Isorthoceras and by curved barrandeocerids, and is considerably less endemic than the benthic fauna of the Boda mounds. Similarities are remarkable at the species level with assemblages from elsewhere in Baltica, with Avalonia and south-western Kazakhstan. A genus-level comparison reveals affinities with Laurentia. However, the genus-level similarities are interpreted as reflecting mainly similarities of the depositional environment and of physicochemical conditions. The presence of calcareous algae in the Boda Limestone and maximum hydrostatic septal strength of cephalopods indicate a depositional depth of <100 m, well within the euphotic zone. The dominance and diversity of cephalopods with vertical migrant lifestyle and the absence of actinocerids indicate a cool, nutrient-rich deeper neritic environment. The post-Katian sediments contain a drastically reduced diversity, dominated by orthocerids. The maximum hydrostatic septal strength of the Hirnantian cephalopods and sedimentological features indicate a shallowing during the Hirnantian, but a continuation of high food availability for cephalopods in the water column.
Place, publisher, year, edition, pages
John Wiley & Sons, 2014. Vol. 47, no 1, 15-30 p.
Boda Limestone, Ordovician, Katian, Hirnantian, Cephalopods, Bivalves
Research subject Earth Science with specialization in Historical Geology and Palaeontology
IdentifiersURN: urn:nbn:se:uu:diva-213233DOI: 10.1111/let.12034ISI: 000328676500003OAI: oai:DiVA.org:uu-213233DiVA: diva2:681376