Revision of Silurian vertebrate biozones and their correlation with the conodont succession

Abstract

The first vertebrate-based subdivisions of Silurian strata were mainly drawn on material from outcrops in Britain and drill cores from the southern Baltic. Nearly twenty years ago the first vertebrate biozonal scheme was developed on the basis of vertebrate distribution in several continuous drill core sections in the northern Baltic. This paper presents a new scheme in which many new data on vertebrate distribution from the Baltica (Baltic region, NW Russia), Avalonia (southern Britain, eastern Canada), Laurentia (northern Canada, Greenland, Scotland) and Kara (Arctic Russia) palaeocontinents have been used. All the zones have been defined, and the geographical distribution and the reference stratum and locality for each zone have been given. The Llandovery part of the succession contains the Valyalepis crista, Loganellia aldridgei and L. scotica zones; the Wenlock part is represented by the Archipelepis bifurcata/Arch. turbinata, L. grossi, Overia adraini, L. einari and Paralogania martinssoni zones. The Par. martinssoni Zone continues in the Ludlow and is followed by the Phlebolepis ornata, Phl. elegans, Andreolepis hedei, Thelodus sculptilis and T. admirabilis zones. The last zone continues in the lower Přidoli and is followed by the Nostolepis gracilis, Poracanthodes punctatus and Trimerolepis timanica zones. The L. aldridgei and Arch. bifurcata zones are new, and the Arch. turbinata and O. adraini faunas have been raised from ‘faunal succession units’ to zones. The geographically widely distributed L. grossi Zone in the upper Sheinwoodian and the Par. martinssoni Zone in the upper Homerian–lowermost Gorstian allow the integration of regional successions into one Generalized Vertebrate Zonal Scheme. Possible correlations of conodont and vertebrate biozones, and gaps in sedimentation in the northern East Baltic Silurian sequence have been discussed, the most extensive hiatus being between the Paadla and Kuressaare stages

Harnessing stratigraphic bias at the section scale: conodont diversity in the Homerian (Silurian) of the Midland Platform, England

“…Oz. bohemica ranges into the lower Gorstian in Britain and elsewhere (Aldridge & Schönlaub ; Viira & Aldridge ; Märss & Männik ) and this range served as a base for the corresponding O. bohemica bohemica Biozone sensu lato , distinguished by Aldridge & Schönlaub (). No better resolved zonations for the middle Silurian in the Midland Platform have been proposed since, therefore the entire interval with Oz.…”

End-Wenlock terminal Mulde carbon isotope excursion in Gotland, Sweden: Integration of stratigraphy and taphonomy for correlations across restricted facies and specialized faunas

“…falls within the C. murchisoni Zone, i.e. below the Wenlock/Ludlow boundary (Jeppsson et al, 2006;Märss and Männik, 2013). Samtleben et al (2000) identified elevated δ 13 C carb values (up to 2.28‰) in the Klinteberg Fm.…”

“…martinssoni allows assigning the entire studied interval to the Par. martinssoni vertebrate Zone (Karatajūtė-Talimaa, 1978; Märss and Männik, 2013) and Kockelella ortus absidata conodont Zone sensu Melchin et al (2012).…”

“…Estonia and Ukraine it is manifested in a subaerial unconformity resulting in erosion of a large part of the underlying strata recording the CIE (hiatus between the Rootsiküla and Paadla formations, Märss and Männik, 2013; boundary between depositional sequences 3 and 4 in . Gothemshammar 9 is similar to the latter settings in that it lies within the lagoonal facies belt, spread over substantial areas in the low-relief epicratonic platform.…”

Revision of the conodont zonation of the Wenlock–Ludlow boundary in the Prague Synform; pp. 305–311

“…With the exception of the East Baltic (e.g. Märss & Männik 2013), the conodont zonation of the Homerian Stage based on Gotland has not yet been tested in other regions. Two zones, Ozarkodina bohemica longa and Kockelella ortus absidata, were, however, incorporated to the generalized global conodont zonal scale by Cramer et al (2011).…”