Billingen (Lower Arenig/Lower Ordovician) acritarchs from the East European Platform and their palaeobiogeographic significance

Abstract

Billingen (Lower Arenig/Lower Ordovician) sediments of the St. Petersburg region, northwest Russia and the Leba area, northern Poland of the East European Craton yield acritarch assemblages, which are largely homogenous though displaying minor compositional differences that probably reflect a gradient from inner to outer shelf environments. Comparison with coeval acritarch microflora from the Yangtze Platform, South China, shows an overall similarity between Baltoscandian and South Chinese phytoplankton. The widespread uniformity in the fossil microphytoplankton may be related to the extensive global 'evae' sea-level transgression, which characterized the Billingen time. This suggests that during the Tremadoc through early Arenig times, acritarch assemblages displayed essentially an undifferentiated cold-water and oceanic character along the whole margin of Perigondwana in the South, as well as on the South Chinese and Baltic platforms, at middle latitudes (Mediterranean oceanic Realm). Despite this overall similarity, however, some typical taxa of the high-latitude Mediterranean Province (Arbusculidium, Coryphidium and Striatotheca) occur in South China, but are absent in Baltica. This discrepancy is explained as caused by differences in climatic and physiographic conditions that prevailed at the two palaeocontinents at this time. The inferred pattern of oceanic circulation during the Lower Ordovician is consistent with the palynological evidence of a prevailing warmer climate in Baltica than in South China, although the two palaeocontinents occupied the same palaeolatitudinal position

First Appearance Datums (FADs) of selected acritarch taxa and correlation between Lower and Middle Ordovician

“…On Baltica, Raevskaya et al (2004) indicated the occurrence of Dasydorus in the O. evae conodont Biozone of the Billingen Stage in the St. Petersburg area, which again suggests a mid-to late Floian age, equivalent to Stage Slice Fl2 or Fl3 (Fig. 1).…”

“…; Billingen Stage, O. evae conodont Biozone), Poland (Raevskaya et al . ; Billingen Stage, Phyllograptus angustifolius elongatus graptolite Biozone, uppermost Floian Stage) and Baltic Russia (Raevskaya et al . ; Billingen Stage, O. evae conodont Biozone).…”

“…; Billingen Stage, Phyllograptus angustifolius elongatus graptolite Biozone, uppermost Floian Stage) and Baltic Russia (Raevskaya et al . ; Billingen Stage, O. evae conodont Biozone). The P. angustifolius elongatus Biozone correlates with the upper part of Time‐Slice 2c (Webby et al .…”

An Early–Middle Ordovician acritarch and prasinophyte assemblage from the Meitan Formation in Qijiang, Chongqing, South China

“…Raevskaya et al 2004;Yan et al 2010), Peteinosphaeridium (Playford et al 1995), Rhopaliophora (e.g. Raevskaya et al 2004) and Sacculidium (e.g.…”

Palynology of the Middle Ordovician Hawaz Formation in the Murzuq Basin, south-west Libya

“…Previous stratigraphic record: Early Tremadocian of Iran (Ghavidel-syooki 2006); Caradoc of England (Turner 1982; reworked specimens); Arenig of Iran (Ghavidelsyooki 2001); Floian-Darriwilian of Argentina (Aráoz 2009); early Arenig of Russia (Raevskaya et al 2004); Tremadocian-Darriwilian of northern Gondwana (Vecoli & Le Hérissé 2004).…”