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Qi C, Kohlstedt DL, Katz RF, et al. Experimental test of the viscous anisotropy hypothesis for partially molten rocks. Proc Natl Acad Sci U S A. 2015;112(41):12616-20doi: 10.1073/pnas.1513790112.
Qi, C., Kohlstedt, D. L., Katz, R. F., & Takei, Y. (2015). Experimental test of the viscous anisotropy hypothesis for partially molten rocks. Proceedings of the National Academy of Sciences of the United States of America, 112(41), 12616-20. https://doi.org/10.1073/pnas.1513790112
Qi, Chao, et al. "Experimental test of the viscous anisotropy hypothesis for partially molten rocks." Proceedings of the National Academy of Sciences of the United States of America vol. 112,41 (2015): 12616-20. doi: https://doi.org/10.1073/pnas.1513790112
Qi C, Kohlstedt DL, Katz RF, Takei Y. Experimental test of the viscous anisotropy hypothesis for partially molten rocks. Proc Natl Acad Sci U S A. 2015 Oct 13;112(41):12616-20. doi: 10.1073/pnas.1513790112. Epub 2015 Sep 28. PMID: 26417107; PMCID: PMC4611659.
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Proc Natl Acad Sci U S A. 2015 Oct 13;112(41):12616-20. doi: 10.1073/pnas.1513790112. Epub 2015 Sep 28.

Experimental test of the viscous anisotropy hypothesis for partially molten rocks.

Proceedings of the National Academy of Sciences of the United States of America

Chao Qi, David L Kohlstedt, Richard F Katz, Yasuko Takei

Affiliations

  1. Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455; [email protected].
  2. Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455;
  3. Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom;
  4. Earthquake Research Institute, University of Tokyo, Tokyo 113-0032, Japan.

PMID: 26417107 PMCID: PMC4611659 DOI: 10.1073/pnas.1513790112

Abstract

Chemical differentiation of rocky planets occurs by melt segregation away from the region of melting. The mechanics of this process, however, are complex and incompletely understood. In partially molten rocks undergoing shear deformation, melt pockets between grains align coherently in the stress field; it has been hypothesized that this anisotropy in microstructure creates an anisotropy in the viscosity of the aggregate. With the inclusion of anisotropic viscosity, continuum, two-phase-flow models reproduce the emergence and angle of melt-enriched bands that form in laboratory experiments. In the same theoretical context, these models also predict sample-scale melt migration due to a gradient in shear stress. Under torsional deformation, melt is expected to segregate radially inward. Here we present torsional deformation experiments on partially molten rocks that test this prediction. Microstructural analyses of the distribution of melt and solid reveal a radial gradient in melt fraction, with more melt toward the center of the cylinder. The extent of this radial melt segregation grows with progressive strain, consistent with theory. The agreement between theoretical prediction and experimental observation provides a validation of this theory.

Keywords: basalt; melt segregation; olivine; partial melts; viscous anisotropy

References

  1. Nature. 2006 Aug 10;442(7103):676-9 - PubMed
  2. Science. 2009 Apr 24;324(5926):499-502 - PubMed
  3. IEEE Trans Pattern Anal Mach Intell. 1986 Jun;8(6):679-98 - PubMed

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