Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Journal of the Geological Society

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by DRAUT, A. E. Articles by CLIFT, P. D. Search for Related Content GeoRef GeoRef Citation

The origin and significance of the Delaney Dome Formation, Connemara, Ireland

^{1 1}Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program in Oceanography, Woods Hole, MA 02543, USA (e-mail: adraut@whoi.edu)
^{2 2}Department of Geology and Geophysics, Woods Hole Oceanographic Institution,Woods Hole, MA 02543, USA

Dalradian meta-sediments of the Laurentian margin and mafic intrusions thereof in SW Connemara, Ireland, tectonically overlie meta-rhyolites of the Delaney Dome Formation. The two units are separated by the Mannin Thrust. A new U–Pb age of 474.6 ± 5.5 Ma shows that the Delaney Dome Formation is a temporal equivalent of arc volcanic rocks preserved in the adjacent South Mayo Trough: the Tourmakeady Volcanic Group, erupted during the collision of an oceanic island arc with the Laurentian margin in the Grampian Orogeny. New rare earth and high field strength element data show that the Delaney Dome Formation and Tourmakeady Volcanic Group are chemically similar and arc-like in character. This suggests that the Delaney Dome Formation is an along-strike equivalent of the Tourmakeady Group, strike-slip faulted south of the South Mayo Trough during or after the Grampian Orogeny. Further correlation of these units with northern Appalachian rhyolites is also possible. The Delaney Dome Formation is an extrusive temporal equivalent of intrusions that penetrate the Connemara Dalradian. Thus, movement along the Mannin Thrust brought mid-crustal plutons and Dalradian country rocks tectonically above the extrusive volcanic sequence. The Mannin Thrust is identified as a major imbricating structure within a continental arc, but not a terrane boundary.

KEYWORDS: Ireland, Grampian Orogeny, U–Pb, geochemistry, subduction, plate collision.

This article has been cited by other articles:

				P. D. Ryan Preservation of forearc basins during island arc-continent collision: Some insights from the Ordovician of western Ireland Geological Society of America Special Papers, January 1, 2008; 436(0): 1 - 9. [Abstract] [Full Text] [PDF]

				P. D. Clift, H. Schouten, and A. E. Draut A general model of arc-continent collision and subduction polarity reversal from Taiwan and the Irish Caledonides Geological Society, London, Special Publications, January 1, 2003; 219(1): 81 - 98. [Abstract] [PDF]