Dr. James H. Wittke

Geologic Materials Analyst

Education 

PhD, The University of Texas at Austin

Specialties 

Igneous petrology, meteoritics, cosmochemistry

Research interests

I supervise operations of the electron microprobe laboratory in Bilby Research Center, which houses a four-spectrometer Cameca SX-50 microprobe. With co-worker Ted Bunch, I maintain the Northern Arizona Meteorite Laboratory and its attendant web site.  My research interests focus on petrologic problems ranging from the petrogenesis of terrestrial basaltic rocks to meteorites to impact products.

My most recent activities have been as part of an international team of researchers that have proposed air bursts of comets or low-density asteroids as the cause of the Younger Dryas cooling, associated megafaunal extinctions, and, possibly, the demise of the Clovis Culture. We continue to document impact products found at the Younger Dryas Boundary layer (YDB), including nanodiamonds, melt glasses, spherules, iridium, and lechatelierite (molten silica).

Publications (2010 - Present) 

J. H. Wittke, J. C. Weaver; T. E. Bunch, J. P. Kennett, D. K. Kennett, A. M. T. Moore, G. C. Hillman, K. B. Tankersley, A. C. Goodyear, C. R. Moore, R. Daniel, J. H. Ray, N. H. Lopinot, D. Ferraro, I-A. Israde, J. L. Bischoff, P. S. DeCarli, R. E. Hermes, J. B. Kloosterman, Z. Revay, G. A. Howard, D. R. Kimbel, G. Kletetschka, L. Nabelek, C. P. Lipo, S. Sakai, A. West & R. B. Firestone, 2013, Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago: Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1301760110.

T. E. Bunch, R. E Hermes, A. M. T. Moore, D. K. Kennett, J. C. Weaver, J. H. Wittke, P. S. DeCarli, J. L Bischoff, G. C. Hillman, G. A. Howard, D. R. Kimbel, G. Kletetschka, C. P. Lipo, S. Sakai, Z. Revay, A. West, R. B. Firestone & J. P. Kennett, 2012, High-Temperature Scoria-like Objects and Glassy Spherules: Evidence for a Cosmic Impact with Earth at 12.9 ka: Proceedings of the National Academy of Sciences, 109 (28) E1903-E1912.

M. K. Weisberg, T. E. Bunch, J. H. Wittke, D. Rumble & D. S. Ebel, 2012, Petrology and oxygen isotopes of NWA 5492, a new metal-rich chondrite: Meteoritics & Planetary Science 47, 363-373.

J. P. M. Hodnett, D. K. Elliott, T. J. Olsen & J. H. Wittke, 2012, Ctenacanthiform sharks from the Permian Kaibab Formation, Northern Arizona: Historical Biology: An International Journal of Paleobiology, DOI:10.1080/08912963.2012.683193.

I. Israde-Alcántara, J. L. Bischoff, G. Dominguez-Vázquez, H.-C. Li, P. S. DeCarli, T. E. Bunch, J. H. Wittke, J. C. Weaver, R. B. Firestone, A. West, J. P. Kennett, C. Mercer, S. Xie, E. K. Richman, C. R. Kinzie & W. S. Wolbach, 2012, Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis: Proceedings of the National Academy of Sciences, vol. 109, issue, 13, pp. E738-E747.

A. V. Kurbatov, P. A. Mayewski, J. P. Steffensen, A. West, D. J. Kennett, J. P. Kennett, T. E. Bunch, M. Handley, D. S. Introne, S. S. Que Hee, C. Mercer, M. Sellers, F. Shen, S. B. Sneed, J. C. Weaver, J. H. Wittke, T. W. Stafford Jr., J. J. Donovan, S. Xie, J. J. Razink, A. Stich, C. R. Kinzie & W. S. Wolbach, 2010, Discovery of a nanodiamond-rich layer in the Greenland ice sheet. Journal of Glaciology 56, 749-759.

Abstracts (2010 - 2013)

C. E. Jacobson, G. B. Haxel, J. H. Wittke, J. Hourigan & M. J. Grove, 2013, Significance of newly discovered subduction complex, including partially serpentinzed peridotite, southwest Arizona. Geological Society of America Abstracts with Programs. Vol. 45, No. 7, p.609.

T.E. Bunch, J. H. Wittke, A. J. Irving, P.P. Sipera & D. Pitt, 2013, Mineralogy and Petrology of Northwest Africa 7214: A large Aubrite from Morocco. 76th Annual Meeting of the Meteoritical Society held July 29 - August 2, 2013 in Edmonton, Canada. Published in Meteoritics and Planetary Science Supplement, id. 5244.

T.E. Bunch, J. H. Wittke, A. J. Irving, D. Rumble, 2013, Unique Polymict Breccia Northwest Africa 7531 Composed of Recrystallized LL Clasts Associated with CR Metachondrite Material: Evidence for Highly Equilibrated Ordinary Chondritic Impactors onto the CR Chondrite Parent Body. 44th Lunar and Planetary Science Conference, held March 18-22, 2013 at The Woodlands, id 2214.

L. Nabelek, G. Kletetschka, J. Kadlec, A. West, T. Bunch, H. Svitavska-Svobodova, and J. Wittke, 2013, Magnetism of microspheres from the proposed Younger Dryas impact event 12,900 years ago. 44th Lunar and Planetary Science Conference, held March 18-22, 2013 at The Woodlands, id 1707.

T. E. Bunch, J. H. Wittke, A. J. Irving, S. M. Kuehner & P. P. Sipiera, 2012, Three Very Highly Shocked Ureilites, NWA 4165, NWA 6871 and NWA 7195: Evidence for Recrystallization and Melting of Silicates and Vaporization of Graphite and Diamond. 75th Annual Meeting of the Meteoritical Society held August 12-17, 2012 in Cairns, Australia. Published in Meteoritics and Planetary Science Supplement, id. 5240.

T. E. Bunch, J. H. Wittke, A. J. Irving & S. M. Kuehner, 2012, Estimation of Petrologic Subtypes of Unequilibrated Ordinary Chondrites from Systematics of Chromium Distributionm in Ferroan Olivine: 43rd Lunar and Planetary Science Conference, held March 19-23, 2012 at The Woodlands, id 2193.