Regional remagnetization of Irish Carboniferous carbonates dates Variscan orogenesis, not Zn-Pb mineralization

Abstract

Research Article| August 01, 2017 Regional remagnetization of Irish Carboniferous carbonates dates Variscan orogenesis, not Zn-Pb mineralization Jamie J. Wilkinson; Jamie J. Wilkinson 1LODE (London Centre for Ore Deposits and Exploration), Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK2Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK Search for other works by this author on: GSW Google Scholar Katie Vowles; Katie Vowles 2Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK Search for other works by this author on: GSW Google Scholar Adrian R. Muxworthy; Adrian R. Muxworthy 2Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK Search for other works by this author on: GSW Google Scholar Conall Mac Niocaill Conall Mac Niocaill 3Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK Search for other works by this author on: GSW Google Scholar Author and Article Information Jamie J. Wilkinson 1LODE (London Centre for Ore Deposits and Exploration), Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK2Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK Katie Vowles 2Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK Adrian R. Muxworthy 2Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK Conall Mac Niocaill 3Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK Publisher: Geological Society of America Received: 06 Feb 2017 Revision Received: 23 Apr 2017 Accepted: 25 Apr 2017 First Online: 23 Jun 2017 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2017 Geological Society of America Geology (2017) 45 (8): 747–750. https://doi.org/10.1130/G39032.1 Article history Received: 06 Feb 2017 Revision Received: 23 Apr 2017 Accepted: 25 Apr 2017 First Online: 23 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jamie J. Wilkinson, Katie Vowles, Adrian R. Muxworthy, Conall Mac Niocaill; Regional remagnetization of Irish Carboniferous carbonates dates Variscan orogenesis, not Zn-Pb mineralization. Geology 2017;; 45 (8): 747–750. doi: https://doi.org/10.1130/G39032.1 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 SocietyGeology Search Advanced Search Abstract Paleomagnetic methods have been used in economic geology to date mineralization in sediment-hosted ore deposits and thereby help to develop ore deposit models and understand the geodynamic settings in which mineralization can occur. However, paleomagnetic ages are sometimes inconsistent with other geochronological techniques and with geological observations. Here we test the veracity of paleomagnetic ages for sediment-hosted ores through a study of the Irish Midlands ore field. We find that unaltered rocks distal to mineralization that are of equivalent age to the ore host sequence have comparable characteristic remanent magnetic directions to those previously derived from the ores. This indicates that remagnetization of the rocks was probably independent of the ore-forming process. Comparison with the apparent polar wander path for Europe suggests an age of ca. 310 Ma for this event, consistent with the timing of the Variscan orogeny. Fold test results support this, indicating the signal was acquired after tilting and/or folding of the host rocks. Petrology and magnetic data suggest that nanometric magnetite particles are the remanence carrier. Based on independent geochronological and geological constraints, we conclude that mineralization formed in Ireland in the early Carboniferous coincident with basin development and that paleomagnetic dates were reset during the later orogenic overprint. Caution is therefore warranted in the interpretation of paleomagnetic dates for ore systems, and geodynamic models for mineral systems based on these may be erroneous. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.