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The Viscosity of Water at High Pressures and High Temperatures: A Random Walk through a Subduction Zone

Pigott, Jeff S.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1299607953

Abstract Details

2011, Master of Science, Ohio State University, Geological Sciences.
The viscosity of water is a first-order constraint on the transport of material from a subducting plate to the mantle wedge. The viscosity of fluids that are released during the dehydration of hydrous minerals during subduction can vary by more than 9 orders of magnitude between the limits of pure liquid water and silicate melts. Accurate determination of low viscosities (<1 mPa·s) for liquids at simultaneous high pressures (>1 GPa) and high temperatures (>373 K) is hindered by the geometry and sample size of high-pressure devices. Here the viscosity of water at pressures representative of the deep crust and upper mantle through use of Brownian motion in the hydrothermal diamond anvil cell (HDAC) is reported. By tracking the Brownian motion of 2.8 and 3.1 micron polystyrene spheres suspended in H2O, the viscosity of the water at high pressure and high temperature can be determined in situ using Einstein’s relation. Accuracies of 3-10% are achieved and measurements are extended to pressures relevant to fluid release from subducting slabs and temperatures up to 150% of the melting temperature. Unhampered by wall effects of previous methods, the results from this study are consistent with a homologous temperature dependence of water viscosity in which the viscosity is a function of the ratio of the temperature to the melting temperature at a given pressure. Based on the homologous temperature dependence of water, transport times for fluids released from subducted plates inferred from geochemical proxies are too short for transport via porous flow alone, and suggest transport through a combination of channel-flow and porous flow implying hydrofracturing at 50-150 km depth.
Wendy Panero (Advisor)
Michael Barton (Committee Member)
David Cole (Committee Member)
61 p.
Geophysics
Viscosity; High Pressure; Water; Diamond Anvil Cell; Subduction Zones; Brownian Motion; High Temperature

Recommended Citations

Citations

  • Pigott, J. S. (2011). The Viscosity of Water at High Pressures and High Temperatures: A Random Walk through a Subduction Zone [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299607953

    APA Style (7th edition)

  • Pigott, Jeff. The Viscosity of Water at High Pressures and High Temperatures: A Random Walk through a Subduction Zone. 2011. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1299607953.

    MLA Style (8th edition)

  • Pigott, Jeff. "The Viscosity of Water at High Pressures and High Temperatures: A Random Walk through a Subduction Zone." Master's thesis, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299607953

    Chicago Manual of Style (17th edition)

osu1299607953
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© 2011, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.