Hirnantian (Late Ordovician) brachiopod faunas across Baltoscandia: A global and regional context

Abstract

A diverse, typical Hirnantia brachiopod fauna from terminal Ordovician strata in Latvia extends the distribution of the Kosov Province across much of the Baltic Palaeoplate into the deeper-water facies of the East Baltic. The new data emphasise the co-occurrence of the core elements of the fauna, Eostropheodonta, Dalmanella, Cliftonia, Hindella, Plectothyrella and Hirnantia, in a siliclastic shelfal setting. The fauna has close similarities with faunas elsewhere on Baltica, including Jämtland, the Oslo Region and Västergötland and plot within the Kosov Province in analyses of the global distribution of Hirnantian assemblages. Carbonate facies, first, in Estonia (lower Hirnantian) and, second, in Oslo together with Östergötland (upper Hirnantian) support quite different faunas related to the margins of Laurentia and the Edgewood Province of the midcontinent, respectively. Stable isotope curves, when used with caution, have helped correlate the sections across the eastern Baltic into Sweden.