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Bubble geobarometry: A record of pressure changes, degassing, and regassing at Mono Craters, California

2012; Geological Society of America; Volume: 40; Issue: 8 Linguagem: Inglês

10.1130/g33027.1

1943-2682

James M. Watkins, Michael Manga, Donald J. DePaolo,

earthquake and tectonic studies

Research Article| August 01, 2012 Bubble geobarometry: A record of pressure changes, degassing, and regassing at Mono Craters, California James M. Watkins; James M. Watkins * 1Department of Earth and Planetary Science, University of California–Berkeley, Berkeley, California 94720-4767, USA *E-mail: jwatkins@berkeley.edu. Search for other works by this author on: GSW Google Scholar Michael Manga; Michael Manga 1Department of Earth and Planetary Science, University of California–Berkeley, Berkeley, California 94720-4767, USA Search for other works by this author on: GSW Google Scholar Donald J. DePaolo Donald J. DePaolo 1Department of Earth and Planetary Science, University of California–Berkeley, Berkeley, California 94720-4767, USA2Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Geology (2012) 40 (8): 699–702. https://doi.org/10.1130/G33027.1 Article history received: 16 Nov 2011 rev-recd: 15 Feb 2012 accepted: 25 Feb 2012 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 James M. Watkins, Michael Manga, Donald J. DePaolo; Bubble geobarometry: A record of pressure changes, degassing, and regassing at Mono Craters, California. Geology 2012;; 40 (8): 699–702. doi: https://doi.org/10.1130/G33027.1 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 Water concentration profiles around bubbles offer a new kind of geobarometer. We measure H2O and CO2 concentrations in glass adjacent to bubbles in pyroclastic obsidian from Mono Craters, California (United States). H2O and CO2 concentration gradients are preserved during the eruption and record nonequilibrium degassing. A key result is that H2O is enriched in the glass surrounding the bubbles, indicating that bubbles were resorbing into the melt just prior to the eruption. The required pressure increase for the observed water enrichment is inferred to be the last in a series of pressure cycles with amplitude 5–30 MPa that are caused by repeated fragmentation and annealing. CO2 concentrations vary substantially in individual obsidian clasts, suggesting that slow diffusion of CO2 and nonequilibrium degassing contributes to high CO2/H2O ratios in pyroclastic obsidian from Mono Craters. These data are direct evidence for vapor-melt disequilibrium and demonstrate that degassing paths from a single parental melt need not be unidirectional. Hence volatile concentration gradients offer a tool for evaluating degassing models and inferring time scales of magmatic processes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.