Peri-Gondwanan Ordovician arc magmatism in southeastern Ireland and the Isle of Man: Constraints on the timing of Caledonian deformation in Ganderia

Abstract

Research Article| July 12, 2018 Peri-Gondwanan Ordovician arc magmatism in southeastern Ireland and the Isle of Man: Constraints on the timing of Caledonian deformation in Ganderia Tobias Fritschle; Tobias Fritschle † 1School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland †tobi.fritschle@gmx.de Search for other works by this author on: GSW Google Scholar J. Stephen Daly; J. Stephen Daly 1School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland2Irish Centre for Research in Applied Geosciences (iCRAG), Belfield, Dublin 4, Ireland Search for other works by this author on: GSW Google Scholar Brian McConnell; Brian McConnell 3Geological Survey Ireland, Beggars Bush, Dublin 4, Ireland Search for other works by this author on: GSW Google Scholar Martin J. Whitehouse; Martin J. Whitehouse 4Laboratory for Isotope Geology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden Search for other works by this author on: GSW Google Scholar Julian F. Menuge; Julian F. Menuge 1School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland2Irish Centre for Research in Applied Geosciences (iCRAG), Belfield, Dublin 4, Ireland Search for other works by this author on: GSW Google Scholar Stephan Buhre; Stephan Buhre 5Institut für Geowissenschaften, Johannes Gutenberg-Universität, 55099 Mainz, Germany Search for other works by this author on: GSW Google Scholar Regina Mertz-Kraus; Regina Mertz-Kraus 5Institut für Geowissenschaften, Johannes Gutenberg-Universität, 55099 Mainz, Germany Search for other works by this author on: GSW Google Scholar Daniel Döpke Daniel Döpke 6Department of Geology, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland Search for other works by this author on: GSW Google Scholar Author and Article Information Tobias Fritschle † 1School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland J. Stephen Daly 1School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland2Irish Centre for Research in Applied Geosciences (iCRAG), Belfield, Dublin 4, Ireland Brian McConnell 3Geological Survey Ireland, Beggars Bush, Dublin 4, Ireland Martin J. Whitehouse 4Laboratory for Isotope Geology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden Julian F. Menuge 1School of Earth Sciences, University College Dublin, Belfield, Dublin 4, Ireland2Irish Centre for Research in Applied Geosciences (iCRAG), Belfield, Dublin 4, Ireland Stephan Buhre 5Institut für Geowissenschaften, Johannes Gutenberg-Universität, 55099 Mainz, Germany Regina Mertz-Kraus 5Institut für Geowissenschaften, Johannes Gutenberg-Universität, 55099 Mainz, Germany Daniel Döpke 6Department of Geology, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland †tobi.fritschle@gmx.de Publisher: Geological Society of America Received: 16 Oct 2017 Revision Received: 15 Mar 2018 Accepted: 28 May 2018 First Online: 12 Jul 2018 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2018 Geological Society of America GSA Bulletin (2018) 130 (11-12): 1918–1939. https://doi.org/10.1130/B31949.1 Article history Received: 16 Oct 2017 Revision Received: 15 Mar 2018 Accepted: 28 May 2018 First Online: 12 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Tobias Fritschle, J. Stephen Daly, Brian McConnell, Martin J. Whitehouse, Julian F. Menuge, Stephan Buhre, Regina Mertz-Kraus, Daniel Döpke; Peri-Gondwanan Ordovician arc magmatism in southeastern Ireland and the Isle of Man: Constraints on the timing of Caledonian deformation in Ganderia. GSA Bulletin 2018;; 130 (11-12): 1918–1939. doi: https://doi.org/10.1130/B31949.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The timing of and tectonic controls on Ordovician magmatism and deformation within accreted terranes are key elements in reconstructing the generation of the Caledonian-Appalachian orogen. This paper addresses the topic through integrated geochronological, structural, and multi-isotope geochemical investigation of magmatic arc–related peri-Gondwanan rocks of Ganderian affinity in the Leinster-Lakesman terrane in SE Ireland and the Isle of Man.A basaltic andesite from a previously unrecognized volcaniclastic sequence in the Manx Group at Port-e-Vullen on the Isle of Man yielded an age of 472.7 ± 2.8 Ma (secondary ion mass spectrometry [SIMS] zircon U-Pb), and an arc-related rhyolite from the Avoca volcanic sequence in SE Ireland was dated at 463.6 ± 2.6 Ma. Two granitoids from Graiguenamanagh (SE Ireland) yielded ages of 462.0 ± 2.7 Ma (augen gneiss) and 460.5 ± 3.2 Ma (equigranular granite), whereas the Dhoon granite (Isle of Man) was dated at 457.2 ± 1.2 Ma. Each of the granitic rocks from Graiguenamanagh and Dhoon was previously considered to be of Silurian–Devonian age. In addition, two sheets of the Croghan Kinshelagh granite (SE Ireland) yielded indistinguishable ages of 456.9 ± 2.4 Ma and 455.4 ± 2.8 Ma.Multi-isotopic analyses (SIMS zircon oxygen, laser ablation–multi-collector–inductively coupled plasma–mass spectrometry [LA-MC-ICP-MS] zircon Lu-Hf, whole-rock Sm-Nd) on the rocks of the Leinster-Lakesman terrane suggest a significant source contribution from the Ganderian microcontinent, represented by the Early Ordovician metasedimentary Ribband and Manx Groups.Structural relationships at Graiguenamanagh demonstrate a late Middle Ordovician deformation event at ca. 460 Ma. This deformation appears to be equivalent to the widespread D1 event that affected Early Ordovician rocks in SE Ireland and corresponds to the early structures within the East Carlow deformation zone, previously interpreted as an exclusively Devonian structure. Along strike, the early deformation is spatially associated with serpentinite emplacement. The East Carlow deformation zone is interpreted as an intra-Ganderian suture along which separate fragments of a peri-Gondwanan magmatic arc were juxtaposed at ca. 460 Ma. This deformation represents a Caledonian tectonic event that has not been recognized within Ganderia in the Appalachian sector of the orogen. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.