Identification of the short-lived Santa Rosa geomagnetic excursion in lavas on Floreana Island (Galapagos) by⁴⁰Ar/³⁹Ar geochronology

Abstract

Research Article| May 01, 2016 Identification of the short-lived Santa Rosa geomagnetic excursion in lavas on Floreana Island (Galapagos) by 40Ar/39Ar geochronology Andrea Balbas; Andrea Balbas 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Anthony A.P. Koppers; Anthony A.P. Koppers 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Dennis V. Kent; Dennis V. Kent 2Department of Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey 08854, USA3Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar Kevin Konrad; Kevin Konrad 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Peter U. Clark Peter U. Clark 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Andrea Balbas 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Anthony A.P. Koppers 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Dennis V. Kent 2Department of Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey 08854, USA3Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA Kevin Konrad 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Peter U. Clark 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Publisher: Geological Society of America Received: 25 Nov 2015 Revision Received: 14 Mar 2016 Accepted: 18 Mar 2016 First Online: 09 Mar 2017 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2016 Geological Society of America Geology (2016) 44 (5): 359–362. https://doi.org/10.1130/G37569.1 Article history Received: 25 Nov 2015 Revision Received: 14 Mar 2016 Accepted: 18 Mar 2016 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 Andrea Balbas, Anthony A.P. Koppers, Dennis V. Kent, Kevin Konrad, Peter U. Clark; Identification of the short-lived Santa Rosa geomagnetic excursion in lavas on Floreana Island (Galapagos) by 40Ar/39Ar geochronology. Geology 2016;; 44 (5): 359–362. doi: https://doi.org/10.1130/G37569.1 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 A set of closely related basaltic lava flows (supersite GA-X) on Floreana Island in the Galapagos Archipelago has a published record of an excursional or transitional direction (virtual geomagnetic pole located at 153.1°E, 54.2°S with α95 = 5.0°) and a geomagnetic field strength (1.1 × 1022 Am2) that is only ∼14% of the strength of the modern magnetic field (7.8 × 1022 Am2). The very large age uncertainty of previous dating of a lava flow (G43) from this set, however, has prevented placing this event in the geomagnetic polarity time scale. Here we report highly reproducible and precise 40Ar/39Ar ages on the lava flow that indicate that the distinct geomagnetic excursion is 925.7 ± 4.6 ka (2σ; n = 6; mean square of weighted deviates = 1.23). This shows that this dramatic weakening of the geomagnetic field is associated with the Santa Rosa Excursion instead of the Matuyama-Brunhes polarity reversal. Our high-precision 40Ar/39Ar ages for Floreana provide evidence for the global significance of the Santa Rosa Excursion. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.