New data on Ordovician–Silurian conodonts and stratigraphy from the Severnaya Zemlya Archipelago, Russian Arctic

Abstract

Thirty samples from 22 sections collected by the SWEDARCTIC international expedition to Severnaya Zemlya in 1999 contained Ordovician and Silurian conodont faunas. Several taxa, including Apsidognathus cf. milleri, Aulacognathus cf. kuehni, Nudibelodina sensitiva, Ozarkodina broenlundi and Pterospathodus eopennatus, allow precise dating of the strata in this region for the first time. The occurrence of Aphelognathus pyramidalis and Rhipidognathus aff. R. symmetricus in samples from the Strojnaya Formation fits well with the earlier dating of these strata as latest Ordovician. However, Aphelognathus sp. in sample BG-99/14-a, collected from the upper Ushakov Formation, indicates that at least in the lower reaches of the Ushakov River the top of this formation is considerably younger than considered earlier: the sampled strata are Late, not Early Ordovician in age. In the Ordovician and Silurian the present-day Severnaya Zemlya region was dominated by extensive shallow-water, mainly semi-restricted basin environments with habitat specific faunas. The occurrence of Riphidognathus aff. R. symmetricus at some levels in the Upper Ordovician suggests extreme shallowing episodes in the basin. On Severnaya Zemlya, 'normal-marine' faunas (including Pt. eopennatus) invaded the distal peripheral regions of the wide shallow-water platform at times of maximum sea-level rise only. The occurrence of Oz. broenlundi and N. sensitiva indicates that in the early Silurian the Severnaya Zemlya basin was quite well connected to the basins over modern North Greenland as well as to the Baltic Palaeobasin. The lower Silurian conodont assemblages in the Vodopad to Samojlovich formations are most similar to those described from the eastern Timan-northern Ural region.

The De Long Islands: A missing link in unraveling the Paleozoic paleogeography of the Arctic

“…The Ordovician conodont fauna from Alaska is a distinctive mixture of Laurentian and Siberian-Alaskan endemic forms (Dumoulin et al, 2014). And the Early Paleozoic succession of Severnaya Zemlya suggests a connection with North Greenland and the Baltic palaeobasin (Männik et al, 2009). Analysis of the distribution of Ordovician rhynchonelliform brachiopods across the world reveals that Siberia and Laurentia represented the same biogeographic province (Harper et al, 2013).…”

Lower Silurian conodonts from the Shine Jinst region, southwestern Mongolia

“…In more recent global zonation schemes (Cramer et al, 2011; Melchin et al, 2012), there is a degree of uncertainty concerning the correlation of the expansa Zone to the graptolite zonation, although it is still found to span the Rhuddanian-Aeronian boundary. Pseudolonchodina expansa has also been reported from Canada (Zhang and Barnes, 2002), Alaska (Dumoulin et al, 1997), Estonia (for references, see Männik and Malkowski, 1998), Poland (Männik and Malkowski, 1998), Russia (Männik et al, 2009), Australia (Simpson and Talent, 1995), and Spain (Sarmiento et al, 1994).…”

The Ordovician and Silurian conodonts of Japan: Their biostratigraphical and paleobiogeographical significance

“…ex gr. hassi in Mel'nikov, ), and on Severnaya Zemlya (Russian Arctic; Männik, ; Männik, Bogolepova, Põldvere, & Gubanov, ). Few probable specimens of this conodont have been found in the lower Telychian, in the lowermost Pt.…”