The palaeobiogeographical spread of the acritarchVeryhachiumin the Early and Middle Ordovician and its impact on biostratigraphical applications

Abstract

Veryhachium morphotypes means that they should be used with caution for long-distance correlation.

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

“…Although the Veryhachium trispinosum group is generally common and widespread across palaeocontinents in the later Ordovician, its first occurrence on Baltica is apparently much later than on the Perigondwanan margin (Servais et al . ). The oldest record appears to be from the undivided Kunda Stage (B III ), equivalent to upper Stage Slice Dw1 and Stage Slice Dw2, in the Rapla Borehole of Estonia (Uutela & Tynni ).…”

“…Like the Veryhachium trispinosum group, the V. lairdii group became widespread during the later Ordovician (Servais et al . ). First occurrences of Dactylofusa velifera , another species restricted to Perigondwana, are mostly in Tr3, albeit with some uncertainty in Argentina, but possibly lower in South China (Tr2?)…”

“…The palaeobiogeographical distribution of Veryhachium morphotypes through the Ordovician was discussed by Servais et al . (), with global first occurrences of both groups at high southern palaeolatitudes of Perigondwana (Gondwana, Avalonia) in the Early Ordovician, followed by spreading to mid‐southern palaeolatitudes in Baltica and South China by the Middle Ordovician and a global distribution by the Late Ordovician. The diachronous FADs are reflected in Figure .…”

“…In addition, the Veryhachium trispinosum group became more widespread during later Ordovician stages (Servais et al . ), with a FAD during the Darriwilian on Baltica (Estonia) and subsequently on Laurentia. The diachronous FADs of these taxa limit their use in long‐distance correlation, but nevertheless they might be used to distinguish the latest Tremadocian stage slice (Tr3) from older divisions at high palaeolatitudes.…”

“…5P) and Veryhachium trispinosum group, respectively Lei et al 2013). The palaeobiogeographical distribution of Veryhachium morphotypes through the Ordovician was discussed by Servais et al (2014), with global first occurrences of both groups at high southern palaeolatitudes of Perigondwana (Gondwana, Avalonia) in the Early Ordovician, followed by spreading to mid-southern palaeolatitudes in Baltica and South China by the Middle Ordovician and a global distribution by the Late Ordovician. The diachronous FADs are reflected in Figure 3 Specimens also occur in a messaoudensis-trifidum acritarch assemblage ) from core between depths of 3615.8 m and 3835.3 m in the R€ ugen 5 borehole on the island of R€ ugen off the northern Baltic coast of Germany (Servais & Molyneux 1997), again part of Avalonia.…”