Carboniferous subvolcanic activity on the Beara Peninsula, SW Ireland

✍ Scribed by M. Pracht; J. A. Kinnaird

• Book ID: 101281695
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 355 KB
• Volume: 32
• Category: Article
• ISSN: 0072-1050
• DOI: 10.1002/(sici)1099-1034(199712)32:4<297::aid-gj736>3.0.co;2-x

✦ Synopsis

Magmatic activity associated with the Munster Basin has been more widespread than previously reported. The Munster Basin is a substantial sedimentary basin, and towards the end of its extensional phase of development, at the beginning of the Variscan orogeny in Ireland, numerous intrusions were emplaced into consolidated Upper Devonian and Lower Carboniferous sediments on the Beara Peninsula. One hundred and sixty-four sills and dykes have been mapped which are subalkaline to alkaline in nature. Two separate suites have been identi®ed. The northern suite comprises subalkaline basalts of Cod's Head and Dursey Island which are intruded into Devonian Red Beds, and the southern suite comprises alkali basalts, trachytes and phonolites which crop out along 9 km of the south coast of the Beara Peninsula and are suggested as Brigantian in age. They are intruded into Devonian Red Beds and marine Lower Carboniferous strata and are therefore later than the tholeiitic magmatism on the Iveragh peninsula to the north. The alkaline magmatism on Beara was induced by lithospheric thinning and controlled partly by pre-existing zones of weakness in the Caledonide crust and partly by fracture zones that developed parallel to the Munster Basin margin as it subsided. In contrast to the Iveragh Peninsula, the stretching factor for the Beara lithosphere was never large enough to lead to the production of tholeiitic magmas.