Facies Trends and Large-Scale Architecture of the Pennsylvanian Ross Formation, Western Ireland - New Insight from Cores South of the Shannon
Files in This Item:
|Final_AAPG_Abstract_4th-9th_April_2014.docx||22.75 kB||Microsoft Word||Download|
|Title:||Facies Trends and Large-Scale Architecture of the Pennsylvanian Ross Formation, Western Ireland - New Insight from Cores South of the Shannon||Authors:||Obradors-Latre, Arnau
Haughton, Peter D. W.
|Permanent link:||http://hdl.handle.net/10197/5113||Date:||Apr-2014||Abstract:||The Ross Formation is well exposed in sea cliffs facing the Atlantic and Shannon estuary in western Ireland. It forms the sandy deep-water part of a major shallowing-upward Pennsylvanian succession. Over the last four years, a major behind-outcrop drilling program targeting the Ross Formation has focused primarily on the Loop Head peninsula in west Clare. This has provided a composite Ross cored section (490 m thick) that underpins a new understanding of bed-scale variability and the wider vertical evolution of the system. The focus has now shifted to the key Ballybunion section on the south side of the Shannon, which sits obliquely down-dip (to the east) of the Loop Head area (c. 18 km away). This area is important in that previous outcrop studies have suggested that (1) the character of the lower Ross with its abundant hybrid event beds may reflect a marginal fringe position; (2) an extra sandy section may be present in the uppermost rRoss due to offset stacking of the youngest lobes and (3) some of the upper Ross mass transport units may extend across the estuary from Clare. Two new cores are now available ¿behind¿ the Ballybunion cliff section: a 200 m long PQ borehole straddling the lower Ross and the upper part of the underlying Clare Shale (12-KY-UCD-09), and a 151.5 m long slimhole core acquired by the Geological Survey of Ireland (GSI 09/05). In addition, a re-analysis of the biostratigraphy is underway. Together the matched pair of Kerry boreholes with the outcrop section provide a reference section (480 m thick) that can be compared with the Loop composite section. Both sections have a distinctive precursor cycle involving first stacked thin mudflows and then outsized and coarse grained hybrid event beds. The muddier make-up of the latter at Ballybunion is consistent with a down-dip position based on trends in other basins. The onset of the main Ross system that follows is sandier at Ballybunion than at Loop suggesting the former was more axial at this time. Thereafter hybrid event beds appear not to be as important at Ballybunion. Several of the mass transport units and condensed sections extend across the Shannon and tie the sections.||Funding Details:||European Research Council
Health Research Board
|Type of material:||Conference Publication||Keywords:||Ross Formation;Behind-outcrop drilling;Borehole;Hybrid event beds||Language:||en||Status of Item:||Peer reviewed||Conference Details:||AAPG Annual Meeting, Houston, Texas, United States of America, April, 2014|
|Appears in Collections:||Earth Sciences Research Collection|
Show full item record
This item is available under the Attribution-NonCommercial-NoDerivs 3.0 Ireland. No item may be reproduced for commercial purposes. For other possible restrictions on use please refer to the publisher's URL where this is made available, or to notes contained in the item itself. Other terms may apply.