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DigiMorph Staff Profile

Rich

Richard Ketcham
Associate Professor,
Department of Geological Sciences,
Jackson School of Geosciences
The University of Texas at Austin

B.S. degree, William's College (1987)
Ph.D. degree, The University of Texas at Austin (1995)

DigiMorph Contributions

I manage the UT High-Resolution X-ray CT Facility. In this capacity, I have scanned many of the animals that appear on this site. I have also image processed some specimens, and have helped with some of the specialized computer programming tasks that have allowed images to be showcased on this site.

Research Interests

My primary research responsibility is running the high-resolution X-ray computed tomography facility. Basically the industrial version of a medical CAT scanner, ours is the only such device in a science department in the world, and allows highly detailed, three-dimensional, non-destructive imaging of the interiors of dense objects (rocks, fossils, meteorites, etc) with 2-3 orders of magnitude better resolution than possible with medical systems. In addition to operating the scanner in support of studies by local and visiting students and scientists, my primary research thrust in this area is to “mine” our images for quantitative data. Current projects include measuring items within the a specimen volume (such as clasts, crystals, or vesicles), determining their locations, sizes, shapes, and contact relationships; quantifying three-dimensional fabrics; and measuring fracture and porosity/permeability networks.

I also work on the theory and practice of apatite fission-track (AFT) thermochronology. Utilizing a data set compiled by William Carlson and Ray Donelick, I created a new model of fission-track annealing in apatite that allows apatite variability to be taken into account in interpreting AFT data. I also created a computer program, AFTSolve, that determines the range of thermal histories that are consistent with a data set, and is in use at many fission-track labs around the world.

Another research direction has been to study the thermal structure of continents, by examining the amount and distribution of radioactive heat-producing elements in the crust of the Basin and Range and relating it to regional heat flow patterns. I consider the amount and distribution of heat production one of the “great unknown” geophysical parameters, which is crucial deriving temperatures inside the Earth from first principles.

I am also currently working on an improved numerical depiction of crystal growth during prograde metamorphism on geological time scales, along with William Carlson and Dave Hirsch. This model is aimed at utilized measured size and spatial distributions and zoning patterns of porphyroblasts in metamorphic rocks to determine the values of kinetic parameters (such as activation energies for crystal nucleation and intergranular diffusion) that are impossible or difficult to observe at laboratory time scales.

Publications

Rowe, T., R.A Ketcham, C. Denison, M. Colbert, X. Xu, P.D. Currie. 2001. Forensic paleontology: The Archaeoraptor forgery. Nature 410, 539-540.

Ketcham, R.A., W.D. Carlson. 2001. Acquisition, optimization and interpretation of X-ray computed tomographic imagery: applications to the geosciences. Computers & Geosciences 27, 381-400.

Rubin, A.E., Ulff-Møller, F., Wasson, J.T., and Carlson, W.D. 2001. The Portales Valley meteorite breccia: Evidence for impact-induced melting and metamorphism of an ordinary chondrite. Geochimica et Cosmochimica Acta, 65(2), 323-342.

Ketcham, R.A. 2001. "Can you scan this?": Principals of computed tomography (CT) and how they apply to the imaging and interpretation of fossilized material. Journal of Vertebrate Paleontology, 21(Suppl. No. 3), 67A.

Kappelman, J., Maga, M., Ryan, T., and Ketcham, R.A. 2001. Nondestructive investigation of the functional aspects of trabecular bone architecture using high-resolution X-ray CT. Journal of Vertebrate Paleontology, 21(Suppl. No. 3), 67A.

Rowe, T., Colbert, M.W., Ketcham, R.A., Maisano, J.A., and Owen, P.R. 2001. High-resolution X-ray computed tomography in vertebrate morphology. Journal of Morphology, 248(3), 277.

Runnegar, B., Dollase, W.A., Ketcham, R.A., Colbert, M., and Carlson, W.D. 2001. Early Archean sulfates from western Australia first formed as hydrothermal barites not gypsum evaporates. Geological Society of America, Abstracts with Programs, 33(6).

Hirsch, D.M., Ketcham, R.A., and Carlson, W.D. 2000. An evaluation of spatial correlation functions in textural analysis of metamorphic rocks. Geological Materials Research, 2(1).

Taleff, E.M., T. Leon-Salamanca, R.A. Ketcham, R. Reyes, and W.D. Carlson. 2000. Nondestructive evaluation of cavitation in an Al-Mg material deformed under creep conditions. Journal of Materials Research, 15, 76-84.

Grimaldi, D., Nguyen, T., and Ketcham, R.A. 2000. Ultra-high-resolution X-ray computed tomography (UHR CT) and the study of fossils in amber. In: D. Grimaldi, Ed. Studies on Fossils in Amber, with Particular Reference to the Cretaceous of New Jersey, p. 77-91. Backhuys Publishers, Leiden.

Lang, M., Ketcham, R.A., and Grujic, D. 2000. 3-D partial melt networks: a high resolution computed x-ray tomography study of deformed partial molten rock analogues. Tektonik, Strukturgeologie, Kristallingeologie, Freiburg, Germany.

Carlson, W.D., Denison, C., and Ketcham, R.A. 1999. Visualization and quantitative analysis of igneous textures in three dimensions using high-resolution X-ray computed tomography. Electronic Geosciences, 3(article 3), 14.

Bauer, R.L., Ketcham, R.A., Denison, C., and Carlson, W.D. 1998. X-ray computed tomography (CT) imaging of spiral inclusion trails and the external morphology of garnet porphyroblasts. Eos, 79(17), 357.

Carlson, W.D., Denison, C., and Ketcham, R.A. (1998) Visualization, interpretation, and quantitative analysis of rock textures in three dimensions using high-resolution x-ray computed tomography. Eos, 79, S357.

Ogasawara, Y., Ando, T., Carlson, W.D., and Ketcham, R.A. (1998) Serial-grinding and X-ray CT techniques for 3D observation of rock textures - an example of magma-mingled rock from Colorado. Eos, 79(17), 356.

Proussevitch, A., Ketcham, R.A., Carlson, W.D., and Sahagian, D. (1998) Preliminary results of X-ray CT analysis of Hawaiian vesicular basalts. Eos, 79(17), 360.

Rowe, T., Kappelman, J., Carlson, W.D., Ketcham, R.A., and Denison, C. 1997. High-resolution computed tomography: a breakthrough technology for earth scientists. Geotimes, 42(9), 23-27.

Moline, G.R., Knight, C.R., and Ketcham, R.A. (1997) Laboratory measurement of transport processes in a fractured limestone/shale saprolite using solute and colloid tracers. Geological Society of America, Abstracts with Programs, 29, 370.

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