## Abstract A Late Ordovician (Sandbian), ScotoβAppalachian brachiopod fauna from the Mweelrea Formation in western Ireland confirms a location for the South Mayo Trough adjacent to the Laurentian margin, characterized at this time by a succession of marine excursions over fluviatile environments.
A revision of the Ordovician stratigraphy for the western Ireland Caledonides and implications for tectonic models
β Scribed by Kieran M. Ryan; D. Michael Williams; Drew S. Coleman; Staci Loewy
- Book ID
- 102846201
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 711 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0072-1050
- DOI
- 10.1002/gj.1219
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β¦ Synopsis
Abstract
The western Ireland Ordovician stratigraphy has been previously used to constrain the timing of docking of an island arc and its foreβarc basin with the margin of Laurentia for the British and Irish Caledonides. New field relationships and age data indicate that one of the key formations, the Rosroe Formation (459.2βΒ±β0.8 and 465.1βΒ±β2.1βMa), and its supposed lateral equivalent, the Maumtrasna Formation are younger than previously interpreted. New age data for a tuff band in the Maumtrasna Formation (468.9βΒ±β1.3βMa) also support previous studies showing it can be correlated to the adjacent Mweelrea Formation. The new field evidence, age data and geochemistry contradict some previous studies and show that the Maumtrasna, Rosroe and Derrylea formations can no longer be considered lateral equivalents. Based on the new stratigraphy a revised tectonic model is required with sedimentation in this part of the Caledonides taking place in a foreβarc basin outboard of a continental arc and the oceanic arc was an alongβstrike equivalent of this arc situated in an embayment of the Laurentian margin. Copyright Β© 2010 John Wiley & Sons, Ltd.
π SIMILAR VOLUMES
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, Carr