Advances and problems in Ordovician palynology of England and Wales

Abstract

Acritarchs and chitinozoa are wed to date Ordovicinn rocks in England and Wales, but the data-base for both groups is poor.

The stratigraphy, correlation, provenance and palaeogeography of the Skiddaw Group (Ordovician) in the English Lake District

“…The study of acritarch floras in the Skiddaw Group was initiated relatively recently, but considerable progress has been made in elucidating the microfloral succession (Molyneux 1990), so that acritarchs complement graptolites as biostratigraphical indicators. Problems remain because the ranges of many taxa are not definitively known and some taxa have yet to be described.…”

Biostratigraphy and paleoenvironmental characterization of the Middle Ordovician from the Sierras Subandinas (NW Argentina) based on organic-walled microfossils and sequence stratigraphy

“…Molyneux (1990Molyneux ( , 1999 highlights major changes in the composition of acritarch assemblages around the Arenig/Llanvirn boundary in England, where Arkonia and Frankea representatives first appear (Frankea hamata-Striatotheca rarirrugulata acritarch Zone). Other proposals of biozones for this age correspond to the Algerian Sahara with the Zone E, supposed to be late ArenigLlanvirn (Jardiné et al, 1974), or more probably Llanvirn according to Molyneux et al (1996), Vecoli (1999) and to Jordan, with the JO-3 Palynozone, considered as Llanvirn and containing Frankea (Keegan et al, 1990).…”

Field and biostratigraphic evidence for an unconformity at the base of the Eycott Volcanic Group in the English Lake District

“…The use of acritarchs to date mid and late Ordovician (i.e. post-Arenig) rocks is problematic because their biostratigraphy is poorly documented (Molyneux, 1990). Reliance on acritarchs to date the D. MILLWARD & S. G. MOLYNEUX Eycott Volcanic Group therefore raises the questions: are the microfossils recorded by Downie & Soper (1972) reliable indicators of a Llanvirn age, as these authors suggested, and, if not, do the more recent collections provide diagnostic evidence?…”