Dr. Caleb Holyoke

Research

Dr. Holyoke's research interests are in the general area of mineral and rock physics. In particular, his focus is on identifying and characterizing the grain-scale processes which constrain our understanding of larger scale processes in metamorphic/igneous petrology and structural geology. He uses a variety of data, such as flow strengths, microstructures and phase arrangements to infer the mechanisms of solid-state flow of rocks. Dr. Holyoke's overall goal is to better understand how the strength, kinematics and composition of the crust and upper mantle evolve during large-scale tectonic events.

Dr. Holyoke uses controlled experiments on natural materials in a Griggs-type apparatus that can be used in either hydrostatic or deformation mode over a wide range of pressure, temperature and strain rate conditions to determine grain-scale mechanisms that allow minerals to flow ductilely. He also uses a variety of analytical methods, such as optical, scanning electron and transmission electron microscopy and Fourier-transform infrared spectroscopy to characterize the phase reactions, intracrystalline defects and microstructures produced by different mechanisms. These observations are then applied to the microstructures in natural rocks to infer the mechanisms and conditions which produced them.

Measurement of the mechanical behavior of the samples also provides quantitative flow laws which are critical for accurate modeling of the strengths of the crust and mantle. The use of an experimental approach to geologic problems also allows Dr. Holyoke to isolate specific variables and test one at a time to avoid the complications that commonly exist in natural rocks.

Projects

Shear-induced fabric and weakening of olivine and dependence on pressure and water

Melt-assisted grain boundary sliding in naturally and experimentally deformed granitic rocks

Strain weakening and/or localization mechanisms in naturally and experimentally deformed granitic rocks

Experimental deformation of talc and pyrophyllite

Experience

• Assistant Research Scientist, Texas A&M University, 2007-date
• Visiting Scholar, University of Tennessee, Knoxville, 2006-2007
• Post-Doctoral Scholar, University of Wisconsin, Madison, 2005-2006
• Lecturer, University of Rhode Island, 2005, 2006
• Research Assistant and Teaching Assistant, Brown University, 2000-2005
• Teaching Assistant, University of Vermont, 1998-2000
• Geologist and Project Manager, MARCOR Environmental, Inc. 1994-1998
• Teaching Assistant, James Madison University, 1991-1994

Publications

• Webber, C., Holyoke, C. W., Newman, J. Little, T., and Tikoff, B. Fabric development in cm-scale shear zones. Red Hills, New Zealand. In review. Tectonophysics.

• Holyoke, C. W. and Tullis, J. 2006. The interaction between reaction and deformation: an experimental study using a biotite + plagioclase + quartz gneiss. Journal of Metamorphic Geology, v. 24, no. 8, p. 743 - 762.

• Holyoke, C. W. and Tullis J. 2006. Mechanisms of weak phase interconnection and the effects of phase strength contrast. Journal of Structural Geology, v. 28, no. 4, p. 621-640.

• Holyoke, C. W. and Tullis, J. 2006. Formation and maintenance of shear zones. Geology, v. 34, no. 2, p 105-108.

• Holyoke, C. W. and Rushmer, T. 2002. An experimental study of grain scale melt segregation mechanisms in two common crustal rock types. Journal of Metamorphic Geology, v. 20, no. 5, p. 493-512.

• Stanley, R., Rushmer, T., Holyoke, C. and Lini, A. 1999. Faults and fluids in the Vermont foreland and western hinterland. In Wright, S. F. ed., Guidebook to Field Trips in Vermont and Adjacent Regions of New Hampshire and New York. New England Intercollegiate Geological Conference, no. 91, p. 135 – 158.