Basalt sills of the U reflector, Newfoundland Basin: A serendipitous dating technique

Abstract

Research Article| December 01, 2005 Basalt sills of the U reflector, Newfoundland Basin: A serendipitous dating technique Garry D. Karner; Garry D. Karner 1Lamont-Doherty Earth Observatory, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar Donna J. Shillington Donna J. Shillington 2National Oceanography Centre, Southampton, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK Search for other works by this author on: GSW Google Scholar Author and Article Information Garry D. Karner 1Lamont-Doherty Earth Observatory, Palisades, New York 10964, USA Donna J. Shillington 2National Oceanography Centre, Southampton, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK Publisher: Geological Society of America Received: 16 Jun 2005 Revision Received: 11 Aug 2005 Accepted: 12 Aug 2005 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2005) 33 (12): 985–988. https://doi.org/10.1130/G21971.1 Article history Received: 16 Jun 2005 Revision Received: 11 Aug 2005 Accepted: 12 Aug 2005 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Garry D. Karner, Donna J. Shillington; Basalt sills of the U reflector, Newfoundland Basin: A serendipitous dating technique. Geology 2005;; 33 (12): 985–988. doi: https://doi.org/10.1130/G21971.1 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 High core recovery at Ocean Drilling Program (ODP) Leg 210, Site 1276, provided a high-resolution porosity-depth relationship and an equally impressive age-depth model based on first and last occurrences of microfossils. Site 1276 was drilled over transitional crust in the Newfoundland nonvolcanic margin, offshore Canada, between known continental crust on the west and apparent oceanic crust on the east as identified by seafloor-spreading magnetic anomalies M3 to M0 (Barremian–Aptian, 129.8–124.8 Ma). At Site 1276, two diabase sills were drilled at depths equivalent to the U reflection, a bright reflection that overlies transitional crust interpreted from seismic reflection profiles throughout the Newfoundland Basin. The sills were emplaced within uppermost Aptian fine- to coarse-grained sediments, 100–200 m above basement as estimated from seismic reflection data. Magma emplacement occurred at shallow levels within the sediment column, as evidenced by: (1) the occurrence of vesicles in the sill, and (2) compaction-induced folding of calcite veins that were emplaced near vertically in the sediments and are assumed to be coeval with the intrusion. By calculating the degree of shortening of the calcite veins and determining the reconstructed porosity of the sediments during vein emplacement, the age of magma emplacement can be deduced. From the porosity-age curve, the age of sill emplacement is estimated to be 82.5–109.1 Ma, consistent with recent 40Ar/39Ar radiometric dating of the upper sill that gave ages of 105.95 ± 1.78 Ma and 104.7 ± 1.7 Ma. The source of magmatism responsible for the diabase sills is necessarily postrift, and the sills are temporally equivalent to alkali basalts dredged from the Newfoundland Seamounts. The simplest explanation for the Site 1276 diabases and the widespread distribution of the U reflection relates to the migration of the Azores, Madeira, and Canary plumes across the Newfoundland Basin between 80 and 120 Ma. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.