An Ordovician age for the Muggort's Bay Lower Palaeozoic inlier,County Waterford,Ireland—the southernmost exposure of the Irish Caledonides |
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| Authors: | P M Brück M Vanguestaine |
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| Abstract: | The most southerly exposed Lower Palaeozoic strata in Ireland occur on the southwest coast of County Waterford along a 2.5 km long coastal section at Muggort's Bay where they are surrounded by Devonian rocks. Five formations can be distinguished which, in ascending order, are: the Ballycurreen, Carrickbrean, Rathnameenagh, Moanbrack and Killinoorin formations. The total thickness of the succession is over 1800 m. No macrofossils are present, but the lithologies are largely fine‐grained turbidites and subordinate volcanic rocks which closely resemble the Ribband Group seen elsewhere in southeast Ireland and have previously therefore been classified with it. Palynological analysis was undertaken on 25 samples collected from Muggort's Bay, of which eight were productive. Diagnostic microfossils, comprising acritarchs, chitinozoans and scolecodonts, indicate an Early to Middle Ordovician age for both the Rathnameenagh and the Moanbrack formations. These ages confirm that the strata are part of the Ribband Group which elsewhere has been biostratigraphically dated as ranging from Mid‐Cambrian to Mid‐Ordovician. Reworked mid‐Middle Cambrian acritarchs occur in the Moanbrack Formation and reworked late Middle to early Late Cambrian acritarchs in the Rathnameenagh Formation. Despite generally poor preservation of the organic matter, some 20 acritarch species have been distinguished. Among these, three species belong to the herein revised genus Retisphaeridium for which an emended diagnosis is proposed together with two new combinations, Retisphaeridium capsulatum (Jankauskas, 1976 ) Vanguestaine nov. comb. and Retisphaeridium pusillum (Moczydlowska, 1998 ) Vanguestaine nov. comb. Copyright © 2005 John Wiley & Sons, Ltd. |
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| Keywords: | Muggort's Bay Ribband Group County Waterford Ireland acritarchs biostratigraphy reworking Ordovician |
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