N. Maziane-serraj et al., Ordovician and Silurian acritarch assemblages from the west Leinster and Slievenamon areas of southeast Ireland, REV PALAE P, 113(1-3), 2000, pp. 57-71
The Lower Palaeozoic sequences west of the Leinster Granite and in the Slie
venamon Inlier of southeast Ireland have been palynologically re-investigat
ed. Most of the productive samples yielded sufficient identifiable acritarc
hs for positive stratigraphical age determinations for several of the forma
tions, The samples also include rare cryptospores, scolecodonts and tubular
structures, Previous work in the area west of the Leinster Granite propose
d an unbroken succession from Early Ordovician Ribband Group turbidites and
volcanics passing up conformably to Early Ordovician to Late Silurian Kilc
ullen Group. The new palynological data clearly show that the Kilcullen Gro
up in this area is entirely Silurian (Llandovery-early Wenlock) in age, als
o results obtained from the same group at Slievenamon confirm the previousl
y reported Silurian age. Ordovician acritarchs found in the Kilcullen Group
of both study areas are reworked and range in age from late Tremadoc to Ll
anvirn. The new data reveal a major stratigraphic break between the Ribband
Group dated as Early and Middle Ordovician and the Silurian Kilcullen Grou
p. This major break extends some hundreds of kms southwest to the Dingle Pe
ninsula and possibly equates with a similar discontinuity in the Isle of Ma
n to the northeast. This break would thus appear to be a major feature with
in the northwestern Avalonian margin sequence. (C) 2000 Elsevier Science B.
V. All rights reserved.