Stability of Melt Rich Channels

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Presentation for COSPAR 2008 - Montreal Canada

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Stability of Melt Rich Channels

  1. 1. Stability of melt-rich channels in Earth’s mantle High Pressure and Temperature Experiments of Olivine, Chromite and Mid-Ocean Ridge Basalt (MORB) Kristyn Rodzinyak Dan King, PhD student, Rock and Mineral Physics Lab, Department of Geology and Geophysics, University of Minnesota, Minneapolis Mark Zimmerman, UMN David Kohlstedt, UMN
  2. 2. Melt Transport <ul><li>Modeling Mantle Convection </li></ul>http://www.yorku.ca/esse/veo/earth/image/1-3-2. JPG
  3. 3. Stress Driven Melt Segregation <ul><li>Mid-Ocean Ridges </li></ul><ul><li>Subduction Zones </li></ul>http://www.waterencyclopedia.com/images/wsci_03_img0352.jpg http://sio.ucsd.edu/volcano/about/images/recycle.gif http://visearth.ucsd.edu/VisE_Int/platetectonics/hotspot2.jpg <ul><li>Hot Spots </li></ul>
  4. 4. Samples <ul><ul><ul><li>Composition </li></ul></ul></ul><ul><ul><ul><li>4 to 1 by volume 8 µm olivine and 2 µm chromite </li></ul></ul></ul><ul><ul><ul><li>4% mid-ocean ridge basalt (MORB) </li></ul></ul></ul>Torsion Static Anneal
  5. 5. Sample Preparation Deformation Assembly
  6. 6. Experiments Gas-medium deformation apparatus PI-10 300 MPa ~10 Km depth Torsion Actuator Pressure Vessel Leak Detector Thermocouple
  7. 7. Torsion, 1473K, 300 MPA Data during first deformation. A slow leak (1MPa/ 6 mins) caused the termination of the experiment. Torsion, 1473K, 200MPa Second deformation on sample once rejacketed. Run terminated due to a slip along a boundary indicated by a drastic drop in plots.
  8. 8. Melt-Rich Bands 1000µm No Bands Bands Bands
  9. 9. Results-Torsion Distance (microns) 20 µm
  10. 10. Results-Static Anneal Distance (microns) 20 µm
  11. 11. Scanning Electron Microscope 2 µm
  12. 12. Quenched 1 hour anneal 10 hour anneal
  13. 13. Conclusions <ul><li>Bands still visible after 10 hour anneal </li></ul><ul><li>Suggests driving force for segregation stronger than the dissipation force </li></ul><ul><li>Surface tension driven flow tends to homogenize melt distribution through time </li></ul><ul><li>On planetary objects where gravity is less than that of Earth, surface tension would likely play a larger role </li></ul>
  14. 14. David Kohlstedt’s Rock and Mineral Physics Lab
  15. 15. Special Thanks To… <ul><li>David Kohlstedt’s Rock and Mineral Physics Lab </li></ul><ul><li>Funding provided by NASA’s PGGURP: Planetary Geology and Geophysics Undergraduate Research Program </li></ul>

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