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

About the PNAS Member Editor
Name Kohlstedt, David L.
Location University of Minnesota
Primary Field Geology
Secondary Field Geophysics
 Election Citation
Kohlstedt is a leader in the field of rock deformation and kinetic properties of solid and partially molten systems, focusing on Earth?s upper mantle. His seminal contributions include illuminating the effect of shear deformation on melt segregation and the role of point defects and hydrogen in transport properties.
 Research Interests
With a background in condensed-matter physics and interests in earth and planetary sciences, my research focuses on physical and chemical properties of minerals and rocks at high pressures and temperatures, with particular emphasis on strength. Motivation for our experiments derives from the importance of quantifying the behavior of geological materials under extreme conditions as the basis for understanding and modeling the dynamical behavior and chemical evolution of deep interiors of terrestrial planets. Two central themes in my research involve fluids. First, we study physical mechanisms by which a small amount of water in the form of hydrogen dissolved in nominally anhydrous silicate minerals produces a dramatic reduction in strength. Water weakening has important consequences for convection in Earth's mantle by enabling plate tectonics, a phenomenon that is absent on Venus, a relatively dry planet often considered Earth's twin. A small amount of melt also profoundly affects the strength of otherwise crystalline rocks. Not only is the strength of a partially molten rock sensitive to melt distribution, but also melt distribution is profoundly influenced by deformation. This coupling between deformation and melt distribution results in self-organization of melt into melt-enriched shear zones that not only localize deformation but also provide high permeability paths for rapid transport of melt from depth to Earth's surface.

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