Pyroclastic edifices record vigorous lava fountains during the emplacement of a flood basalt flow field, Roza Member, Columbia River Basalt Province, USA

Abstract

Research Article| July 01, 2014 Pyroclastic edifices record vigorous lava fountains during the emplacement of a flood basalt flow field, Roza Member, Columbia River Basalt Province, USA Richard J. Brown; Richard J. Brown 1Volcano Dynamics Group, Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK †Current address: Department of Earth Sciences, Durham University, Science Labs, Durham, DH1 3LE, UK; e-mail: richard.brown3@durham.ac.uk. Search for other works by this author on: GSW Google Scholar S. Blake; S. Blake 1Volcano Dynamics Group, Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK Search for other works by this author on: GSW Google Scholar T. Thordarson; T. Thordarson 2School of Geosciences, Grant Institute, The King’s Buildings, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JW, UK §Current address: Faculty of Earth Sciences, University of Iceland, Askja, Sturlugata 7, 101 Reykjavik, Iceland. Search for other works by this author on: GSW Google Scholar S. Self S. Self 1Volcano Dynamics Group, Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK Search for other works by this author on: GSW Google Scholar GSA Bulletin (2014) 126 (7-8): 875–891. https://doi.org/10.1130/B30857.1 Article history received: 22 Jan 2013 rev-recd: 03 Dec 2013 accepted: 31 Dec 2013 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Richard J. Brown, S. Blake, T. Thordarson, S. Self; Pyroclastic edifices record vigorous lava fountains during the emplacement of a flood basalt flow field, Roza Member, Columbia River Basalt Province, USA. GSA Bulletin 2014;; 126 (7-8): 875–891. doi: https://doi.org/10.1130/B30857.1 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 1300 km3 tholeiitic lava flow field of the 14.98 Ma Roza Member of the Columbia River Basalt Province has the best-preserved vent system of any known continental flood basalt. Detailed geological mapping and logging of the exposed pyroclastic rocks along the >180-km-long vent system enable the reconstruction of pyroclastic edifices (partial cones) built around vents. The pyroclastic cones differ from those constructed during typical basaltic effusive eruptions and are characterized by low to moderate slope angles (<20°), have minimum heights up to ∼160 m, and are composed of dominantly coarse-grained, moderately to densely agglutinated and welded spatter and scoria that extend up to 750 m away from the vent. Thick, well-sorted fall deposits composed of moderately to highly vesicular scoria lapilli extend away from some vents and exhibit some characteristics comparable to the proximal deposits of violent Strombolian or subplinian eruptions. The recorded volcanic activity does not fit with common eruption styles of basaltic magmas, and the evidence indicates that the Roza eruption was punctuated by eruptive activity of unusually high intensity that was characterized by vigorous lava fountains. The extensive agglutinated deposits accumulated around the vents as a result of fallout from high (>1 km) fountains enhanced by fallout from the lower parts of convective plumes that rose above the fountains. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.