Taxonomy and biostratigraphy of Silurian-Devonian foraminifera from Eastern Australia
thesisposted on 2022-03-28, 21:23 authored by Kenneth Neil Bell
Silurian to Middle Devonian sequences in Eastern Australia are shown to contain a large foraminiferan fauna. This fauna includes both agglutinated test and calcareous test species and comprises 19 families, 43 genera and 100 species of which four genera (Cystingarhiza, Cylindrammina, Patellammina and Vermiculammina) and 37 species are proposed as new. The new specific taxa include six species described from inner organic wall linings. The Silurian to Early Devonian faunas are entirely of agglutinated species, with the earliest calcareous test foraminiferan entering in the Emsian (serotinus Conodont Zone). The later faunas are dominated by the calcareous forms. Significant time range extensions have been found for the genera Pelosina, Sagenina, Reophanus, Trochammina and Nanicella. As well as the normal-sized foraminiferans in the fauna there were found, for the first time, organic linings which are considered to be the remains of agglutinated foraminiferans. They are a smaller size range of foraminiferans than is usually studied and represent foraminiferans which may or may not have had an inorganic outer wall. Many can be identified with known normal-sized foraminiferal genera and species and six new species, known only from organic linings, are described. These linings, recovered from samples from Australia, France, Siberia and Pakistan, also show usefulness as intra-continental and inter-continental correlation indicators. A biostratigraphic zonation for the Silurian and Early-Middle Devonian of Eastern Australia, based on both normal foraminiferans and the organic linings, is proposed.