Belgian substages as a basis for an international chronostratigraphic division of the Tournaisian and Viséan

Abstract

The Tournaisian and Viséan were formerly considered as series and in Belgium were divided into two (Hastarian and Ivorian) and three stages (Moliniacian, Livian and Warnantian), which are now considered as substages. The Belgian substages are based on conodonts and foraminifers, and incidentally on rugose corals, and are described here. Their boundaries, biostratigraphy and sequence stratigraphy are well detailed and clearly defined. The base of the Hastarian (lower Tournaisian) corresponds to the base of the Tournaisian (base of Carboniferous); the base of the Ivorian (upper Tournaisian) corresponds to the appearance of the conodont Polygnathus communis carina, a little above the last Siphonodella; the base of the Moliniacian (lower Viséan) corresponds to the base of the Viséan stage defined by the first occurrence of the foraminifer Eoparastaffella simplex; the Livian (middle Viséan) corresponds to the foraminiferal MFZ12 Zone and is marked by the appearance of Koskinotextularia and Pojarkovella nibelis; the base of the Warnantian (upper Viséan) is marked by the appearance of Neoarchaediscus, Vissariotaxis, Planospirodiscus, and Palaeotextularia with a bilaminar wall, the index taxa of the MFZ13-Neoarchaediscus Zone. The up-to-date chronostratigraphic subdivision of the Tournaisian and Viséan is not limited to Belgium and the surrounding areas. It can be applied through Eurasia as far as South China. The Belgian units could therefore be the basis for a future international division of the Tournaisian into two parts (Hastarian and Ivorian) and of the Viséan into three parts (Moliniacian, Livian and Warnantian), corresponding to time intervals of c. 5–8 Ma.

Upper and uppermost Famennian (Devonian) brachiopods from north-western France (Avesnois) and southern Belgium

“…Hance et al (2001) correlated the Avesnelles Formation with the two first members (α and β) of the Hastière Formation and thus, according to E. Poty (pers. com., October 2015), only its base (the equivalent of the bed 159 of the Hastière Formation in the Anseremme section (see Poty et al, 2014)), could be correlated with the Upper praesulcata Zone. Although Poty et al (2006) have assigned the whole Avesnelles Formation to the Upper praesulcata Zone and thus considered it as entirely uppermost Famennian and not Tournaisian in age, we have followed the first opinion here.…”

“…Conil, 1968;Poty et al, 2014) and Gendron-Celles (e.g. Conil, 1968), from the Comblain-au-Pont Formation at Royseux (e.g.…”

“…In the Anseremme section ( Fig. 1; see log in Poty et al, 2014), which has been selected as the neostratotype of the base of the Hastarian Substage , the base of the Carboniferous, and thus that of the Tournaisian Stage and the Hastarian Substage, is placed at the base of the bed 162 (e.g. Poty et al, 2014).…”

“…1; see log in Poty et al, 2014), which has been selected as the neostratotype of the base of the Hastarian Substage , the base of the Carboniferous, and thus that of the Tournaisian Stage and the Hastarian Substage, is placed at the base of the bed 162 (e.g. Poty et al, 2014). This boundary was drawn on the basis of the disappearance of reworked 'Devonian' fauna and conodonts of the praesulcata Zone, because above bed 159 in this section there was no palaeontological criterion for defining the base of the Hastarian (Conil et al, 1986;Poty et al, 2014).…”

“…This boundary was drawn on the basis of the disappearance of reworked 'Devonian' fauna and conodonts of the praesulcata Zone, because above bed 159 in this section there was no palaeontological criterion for defining the base of the Hastarian (Conil et al, 1986;Poty et al, 2014). According to Poty et al (2014), at Anseremme, the Hangenberg Extinction Event, although it is not marked lithologically, has to be placed at the top of the Etroeungt Formation notably on the basis of the extinction of the representatives of the foraminifer genus Quasiendothyra and the ostracod genus Cryptophyllus as well as the presence of reworked Strunian rugose corals at the base of the bed 159, which corresponds to the first bed of the Hastière Formation. At Royseux (e.g.…”