Rapid magma ascent recorded by water diffusion profiles in mantle olivine
- 1Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, and Institut für Geowissenschaften, Universität Tübingen, D-72074 Tübingen, Germany, and Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston, Texas 77058, USA
- 2Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, and Carnegie Institution of Washington, Geophysical Laboratory, 5251 Broad Branch Rd. NW, Washington, District of Columbia 20015, USA
- 3Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany, and Institut des Sciences de la Terre d'Orléans, Université d'Orléans, 1A rue de la Ferollerie, F-4507 Orléans Cedex, France
- 4Department of Geological Sciences, University of Colorado–Boulder, Boulder, Colorado 80309, USA
Abstract
Mechanisms and rates of magma ascent play a critical role in eruption dynamics but remain poorly constrained phenomena. Water, dissolved in mantle minerals as hydrogen and partitioned into the magma during ascent, may provide clues to quantifying magma ascent rates prior to eruption. We determined the dehydration profiles in olivine crystals from peridotite mantle xenoliths within the Pali-Aike alkali basalt from Patagonia, Chile. The results demonstrate that the amount of water stored in the uppermost mantle has likely been underestimated due to water loss during transport. Using experimental diffusion data for hydrogen, we estimate that the xenoliths reached the surface from 60–70 km depth in several hours, a surprisingly rapid rise comparable to ascent rates for kimberlite magmas.
Footnotes
-
↵*Present address: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, Minnesota 55455, USA; demou005{at}umn.edu
-
↵GSA Data Repository item 2006084, Table DR1, sample descriptions, analytical methods and diffusion analysis, Table DR2, and Figure DR1, is available online at www.geosociety.org/pubs/ft2006.htm, or on request from editing{at}geosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301, USA.
-
- Accepted 12 January 2006.
- Received 1 November 2005.
- Revision received 9 January 2006.
- The Geological Society of America, Inc.
