Melt segregation in a deforming partially molten rock - an experimental investigation of the consequences of viscous anisotropy

GSTDTAP

项目编号	1520647
	Melt segregation in a deforming partially molten rock - an experimental investigation of the consequences of viscous anisotropy
	David Kohlstedt
主持机构	University of Minnesota-Twin Cities
项目开始年	2015
	2015-07-01
项目结束日期	2018-06-30
资助机构	US-NSF
项目类别	Continuing grant
项目经费	113235(USD)
国家	美国
语种	英语
英文摘要	Melt segregation in a deforming partially molten rock ? An experimental investigation of the consequences of viscous anisotropy Kohlstedt - Extraction of melt from mantle rocks composed of solid grains plus 1 or 2% melt results in eruption of magma at Earth?s surface. This process controls the chemical and physical evolution of our planet. Since processes occurring at great depths are not directly observable, much of our understanding of the dynamics of partially molten regions of Earth?s interior relies on numerical/computer models of the behavior of partially molten rocks. The starting point for models of a mechanically weak melt in a strong but deformable rock is known as two-phase flow theory. Application of this theory to large-scale processes occurring far below Earth?s surface requires equations describing the viscosity (strength) and the rate at which melt flows through a rock. An important test of the validity of models used to describe the interactions of deformation, melt distribution, and melt migration in the mantle is their ability to explain phenomena observed in laboratory experiments on partially molten rocks. A fundamental breakthrough in the theory describing the dynamics of partially molten rocks occurred with the publication of three fundamental papers in 2009. These papers explored the implications of anisotropic viscosity (i.e., the directional dependence of the strength of a rock) on melt distribution during deformation. It was hypothesized that viscosity (strength) should be anisotropic because pockets of melt become aligned during deformation. Based on this anisotropic grain-scale melt distribution, it was predicted that melt-rich bands should develop in deforming rocks, consistent with previously experimental observations. This analysis also predicted that solid and melt should segregate from regions of low stress to regions of high stress. Our recent experiments, in fact, demonstrated this behavior in partially molten samples deformed in torsion in our laboratory. A key aspect of our research is a synergistic collaboration with scientists at the University of Oxford (computer models) and Tokyo (theory). Through our cooperative efforts, models based on two-phase flow theory will be tested against experimental observations in order to advance our understanding of how melt flows in Earth?s mantle. While agreement between theory and experiment is clearly important, discrepancies represent an avenue for progress in refining theory. Discrepancies between theoretical prediction and experimental observation represent an opportunity to refine our understanding of the grain-scale mechanics of partially molten rocks. Thus, well-designed experiments with detailed analysis of melt distribution, melt segregation, and mechanical properties are essential. A unique aspect of this research is our involvement in STEM outreach in Mexico though ?Clubes de ciencia México?, an organization of science outreach and mentoring for high school and undergraduate students in Mexico. The science clubs are one-week long, very interactive workshops designed to initiate students to science and research; special focus is given to scientific reasoning and ethics. A recent workshop on ?How do rocks flow?? illustrated the necessity of experimental studies for understanding our planet?s evolution. Outreach will continue through a website and outreach workshops, using our current experimental investigations to explain the implications of experimental research for understanding large-scale dynamics of our planet.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68154
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	David Kohlstedt.Melt segregation in a deforming partially molten rock - an experimental investigation of the consequences of viscous anisotropy.2015.