Palynology of the Lower and Middle Elton Formations (Ludlow Series, Silurian) in the Ludlow type area, Shropshire.
thesisposted on 19.11.2015, 09:06 by G. L. Mullins
This thesis documents and analyses the distribution of acritarchs, prasinophyte algae and palynofacies at the basal stratotype of the Ludlow Series (Silurian) at Pitch Coppice Quarry, Ludlow, Shropshire, and the nearby Goggin Road section. Ten new species are erected; Cymatiosphaera lawsonii, Cymatiosphaera multicrista, Cymatiosphaera paucimembrana, Cymatiosphaera triangula, Baltisphaeridium. spinatum, Buedingiisphaeridium reticulum, Glyptosphaera heltaskelta, Gorgonisphaeridium. listen, Leptobrachion digitatum and Pulvinosphaeridium dorningii; 31 new species are described in open nomenclature. The diagnoses of Psenotopus, Psenotopus chondrocheus, Cymatiosphaera octoplana, Dorsennidium europaeum, Dorsennidium rhomboidium, Eupoikilofusa filifera, Evittia robustispinosa, Pulvinosphaeridium oligoprojectum, Schismatosphaeridium rugulosum and Veryhachium trisphaeridium are emended. Six new combinations are proposed; Comasphaeridium brevispinosum, Dorsennidium polygonale, Dorsennidium wenlockianum, Evittia aculeata, Evittia almarada, Gorgonisphaeridium citrinum. The ranges of Buedingiisphaeridium pyramidale and Neoveryhachium mayhillense are extended, producing an overlap between biozones W3 and LI of Doming (1981a). Biozone L2 may, possibly, be recognised by G. listeri 78.4m above the series boundary (Middle Elton Formation). Zone 6 (Gorstian-Ludfordian stages) of Martin (1989) is identified by Percultisphaera stiphrospinata (+83.5m, Middle Elton Formation). Potentially important taxa for future biostratigraphic research are highlighted and these may be used to refine the existing biostratigraphic schemes. The palynofacies analysis undertaken identifies a Wenlock-Ludlow series boundary event correlating with the delta13C event of Corfield et al. (1992). Transgression induced reworking, concentrating 12C rich organic matter, is proposed as the cause. Between Pitch Coppice and Goggin Road this event is diachronous. Individual taxa, which occur through the section in ~80% of samples, are grouped by cluster analysis. These groups, and the distribution of rarer taxa, are related to the palynofacies analysis, and a series of events are proposed (fluctuations in sea-level, marine/terrestrial productivity, sedimentation rates, palaeoenvironment, palaeoceanography) These events are compared to eustatic and climatic/oceanic models.