David L. Goldsby
Associate Professor, Research:
Phone: +1 401 863 1922
I am interested in the deformation of geological materials, studies of rock friction and plastic flow of ice. My rock friction research focuses on gaining an understanding of the fundamental micromechanical processes that are responsible for the dependence of frictional resistance on slip speed, slip displacement and time, with important applications for understanding earthquake mechanics. My ice deformation research focuses on understanding grain-size sensitive flow processes and the ways these may control the deformation of ice on the Earth in glaciers and ice caps as well as on icy satellites, such as those of Jupiter and Saturn.
I received my Ph.D. in Geophysics at the University of Minnesota/Minneapolis in 1991. I served as a Research Assistant to the Department of Geology and Geophysics at the University of Minnesota from 1991 to 1997. In 1997 I came to the Department of Geological Sciences at Brown University as a Research Associate, and was promoted to Associate Professor, Research in 2008.
My overall research interest is in mineral and rock physics, with an emphasis on the rheological behavior of Earth and planetary materials. Extensive experience in geophysics and materials science laboratories has provided me with a very broad theoretical and practical background in the mechanical behavior and testing of minerals, rocks, and other materials in both the ductile and brittle fields. In the next five years, my goal is to focus on experiments designed to further our understanding of deformation mechanisms in the Earth and other planets. Experiments will be conducted both at high confining pressure and at ambient pressure, at high temperatures in the case of materials like olivine and at cryogenic temperatures in the case of ice and other cryomaterials. Experiments will often employ novel methods developed in materials science both for fabricating and testing of materials, such as hot isostatic pressing of powders to fabricate fine-grained samples and nanoindentation testing to explore small-scale deformation processes. One particular focus of my research has been grain size sensitive flow of materials, a mechanism which involves grain boundary sliding (GBS). This flow behavior is activated at lower stresses than dislocation creep, and therefore can control the rheological behavior of various materials in low-deviatoric-stress natural environments, such as in glaciers and icy planetary interiors, as well as in the interiors of the Earth and other planets. The flow of ice in glaciers, for example, is likely often controlled by GBS acting in concert with dislocation motion; this is an ice creep mechanism I discovered and characterized with David Kohlstedt at the University of Minnesota.
Within the broader scope of mineral and rock physics, there are several specific research topics I am interested in, including:
- 1) the rheological behavior of pure and impure ices relevant to flow of glaciers, ice sheets, and icy satellites of the outer solar system,
- 2) the tribological behavior of rocks relevant to earthquake mechanics, and
- 3) low-temperature creep of geologic materials relevant to the frictional properties of rocks and the strength of the lithosphere.
Lecturer, Brown University Spring 2005 - Taught a three-week series of classes on the rheology of ice in graduate-level GEOL 2920 - Problems in Antarctic Dry Valley Geoscience.
Mentor, Brown University Summer 2004 - Served as Faculty Mentor to Carla Roig Silva, a minority summer undergraduate intern in the Leadership Alliance Program.
Lecturer, Brown University - Lectured on ice rheology in graduate-level GEOL 2530 - Deformation Mechanisms.
Graduate Seminar Organizer, University of Minnesota 1995 - Organized and directed a graduate-level reading seminar with David Kohlstedt on the role of grain boundaries and interfaces in geologic processes.
Teaching Assistant, University of Minnesota, 1990 to 1992 - Taught laboratory sections of Introductory Geology.
Recent Research Funding:
NSF-EAR, Co-PI with Terry Tullis and Robert Carpick (U. Penn), Collaborative Research: Rock Friction, Nanoindentation, and Atomic Force Microscope Experiments Focused on Understanding
NSF-EAR, Co-PI with Vikas Prakash (Case-Western), Collaborative Research: Laboratory Experiments to Understand Dynamic Slip Weakening in Rocks and Analog Materials.
IODP Participant Support Funds to conduct post-cruise experiments on materials recovered from Stage 1 NanTroSEIZE drilling.
NSF-EAR, Co-PI, Laboratory Investigations of the Origin of Fault-Zone Pulverized Rock.
NASA-PGG, PI, A Continuing Laboratory Study of the Rheology of Impurity-Bearing Water Ice.
USGS-NEHRP, Co-PI with Terry Tullis, Experiments to Understand Dynamic Friction During Earthquakes.
NSF-EAR, Co-PI with Terry Tullis, Laboratory Experiments on Rock Friction Focused on Understanding Earthquake Mechanics.
NASA-PGG, Co-I with Reid Cooper, Viscoelastic and Plastic Rheologies of Eutectic Water-Ice/Salt- Hydrate Aggregates with Application to Tectonic Processes on Europa.