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Spherulites as in-situ recorders of thermal history in lava flows

2015; Geological Society of America; Volume: 43; Issue: 7 Linguagem: Inglês

10.1130/g36639.1

1943-2682

Kenneth S. Befus, James M. Watkins, James E. Gardner, D. Richard, Kevin M. Befus, Nathan Miller, Donald B. Dingwell,

Geological formations and processes

Research Article| July 01, 2015 Spherulites as in-situ recorders of thermal history in lava flows Kenneth S. Befus; Kenneth S. Befus 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar James Watkins; James Watkins 2Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA Search for other works by this author on: GSW Google Scholar James E. Gardner; James E. Gardner 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Dominique Richard; Dominique Richard 3Department of Earth and Environmental Sciences, Ludwig Maximilian University of Munich, Theresienstrasse 41/III, 80333 Munich, Germany Search for other works by this author on: GSW Google Scholar Kevin M. Befus; Kevin M. Befus 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Nathan R. Miller; Nathan R. Miller 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Search for other works by this author on: GSW Google Scholar Donald B. Dingwell Donald B. Dingwell 3Department of Earth and Environmental Sciences, Ludwig Maximilian University of Munich, Theresienstrasse 41/III, 80333 Munich, Germany Search for other works by this author on: GSW Google Scholar Author and Article Information Kenneth S. Befus 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA James Watkins 2Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA James E. Gardner 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Dominique Richard 3Department of Earth and Environmental Sciences, Ludwig Maximilian University of Munich, Theresienstrasse 41/III, 80333 Munich, Germany Kevin M. Befus 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Nathan R. Miller 1Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712, USA Donald B. Dingwell 3Department of Earth and Environmental Sciences, Ludwig Maximilian University of Munich, Theresienstrasse 41/III, 80333 Munich, Germany Publisher: Geological Society of America Received: 22 Jan 2015 Revision Received: 12 May 2015 Accepted: 13 May 2015 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2015 Geological Society of America Geology (2015) 43 (7): 647–650. https://doi.org/10.1130/G36639.1 Article history Received: 22 Jan 2015 Revision Received: 12 May 2015 Accepted: 13 May 2015 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Kenneth S. Befus, James Watkins, James E. Gardner, Dominique Richard, Kevin M. Befus, Nathan R. Miller, Donald B. Dingwell; Spherulites as in-situ recorders of thermal history in lava flows. Geology 2015;; 43 (7): 647–650. doi: https://doi.org/10.1130/G36639.1 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 Spherulites in rhyolitic obsidian provide a record of the thermal history of their host lava during the interval of spherulite growth. We use trace element concentration profiles across spherulites and into the obsidian host from Yellowstone National Park (USA) to reconstruct the conditions that existed during spherulite formation. The measured transects reveal three behaviors: expulsion of the most diffusively mobile elements from spherulites with no concentration gradients in the surrounding glass (type 1); enrichment of slower-diffusing elements around spherulites, with concentration gradients extending outward into the glass (type 2); and complete entrapment of the slowest-diffusing elements by the spherulite (type 3). We compare the concentration profiles, measured by laser ablation–inductively coupled plasma–mass spectrometry and Fourier transform infrared spectroscopy, to the output of a spherulite growth model that incorporates known diffusion parameters, the temperature interval of spherulite growth, the cooling rate of the lava, and data on the temporal evolution of spherulite radius. Our results constrain spherulite nucleation to the temperature interval 700–550 °C and spherulite growth to 700–400 °C in a portion of lava that cooled at 10–5.2 ± 0.3 °C s–1, which matches an independent experimental estimate of 10–5.3 °C s–1 measured using differential scanning calorimetry. Maximum spherulite growth rates at nucleation are on the order of 1 μm hr–1 and are inferred to decrease exponentially with time. Hence, spherulites may serve as valuable in-situ recorders of the thermal history of lava flows. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.