Episodic crystallization in young explosive eruptions in Dominica, Lesser Antilles, revealed by U-Th dating of zircons

Abstract

Research Article| September 07, 2018 Episodic crystallization in young explosive eruptions in Dominica, Lesser Antilles, revealed by U-Th dating of zircons Holli M. Frey; Holli M. Frey 1Department of Geology, Union College, Schenectady, New York 12308, USA Search for other works by this author on: GSW Google Scholar Matthew R.F. Manon; Matthew R.F. Manon 1Department of Geology, Union College, Schenectady, New York 12308, USA Search for other works by this author on: GSW Google Scholar Sarah K. Brehm; Sarah K. Brehm 2Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Rebecca N. Babiak Rebecca N. Babiak 3Department of Geology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X5 Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Holli M. Frey 1Department of Geology, Union College, Schenectady, New York 12308, USA Matthew R.F. Manon 1Department of Geology, Union College, Schenectady, New York 12308, USA Sarah K. Brehm 2Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Rebecca N. Babiak 3Department of Geology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X5 Canada Publisher: Geological Society of America Received: 31 May 2018 Revision Received: 03 Aug 2018 Accepted: 05 Aug 2018 First Online: 07 Sep 2018 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2018 Geological Society of America Geology (2018) 46 (10): 887–890. https://doi.org/10.1130/G45217.1 Article history Received: 31 May 2018 Revision Received: 03 Aug 2018 Accepted: 05 Aug 2018 First Online: 07 Sep 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Holli M. Frey, Matthew R.F. Manon, Sarah K. Brehm, Rebecca N. Babiak; Episodic crystallization in young explosive eruptions in Dominica, Lesser Antilles, revealed by U-Th dating of zircons. Geology 2018;; 46 (10): 887–890. doi: https://doi.org/10.1130/G45217.1 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 Understanding the storage conditions of silicic magmas prior to violent volcanic eruptions is important as it places constraints on whether the presence of melt is indicative of volcanic unrest. To address magma reservoir storage conditions in an active volcanic arc system, ignimbrites from the Roseau Tuff in Dominica were characterized by geochronology and thermometry. Sixty-five (65) new U-Th ages of zircon rims from ignimbrites spanning the 10-km-long Roseau Valley demonstrate that the deposits represent multiple distinct eruptive events, including a significant Holocene eruption. The zircons from each ignimbrite show a polymodal age distribution. The youngest zircons capture the eruption or near-eruption age (ca. 3 to ca. 60 ka) of each ignimbrite, whereas a significant older, antecrystic zircon population (80–200 ka) is found in most deposits. The zircon age distributions reflect discrete periods of crystallization punctuated by hiatuses of tens of thousands of years, as opposed to continuous or steady zircon crystallization, based on comparison with synthetic data sets and results from mixing models. Iron-titanium (Fe-Ti) oxide thermometry suggests that the magmas were significantly zircon undersaturated upon eruption and therefore a mafic rejuvenation event driving the eruption was short lived (<2500 yr). The discontinuous nature of the zircon age distribution in the ignimbrites contrasts with the more continuous zircon age distributions in lava domes on Dominica, suggesting that explosive eruptions could be a consequence of subsolidus storage conditions and intermittent rheologic lock-up. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.