James Wittke: Igneous petrology & meteoritics
I supervise the operations of the electron microprobe laboratory,
which houses a Cameca MBX microprobe. My research interests focus upon
petrologic problems ranging from terrestrial igneous rocks to meteorites. I am
collaborating with Richard Holm on ultra-alkaline volcanics and hypabyssal
rocks in central Arizona, and with Ted Bunch on meteorite classifications and
the petrology of impactites from Meteor Crater, Arizona and Argentina. These
form when molten material ejected during meteorite impacts. I have just started
a comprehensive study of the petrology of a new lunar meteorite regolith breccia.
These breccias are complex and contain a wide variety of lunar rock types. I am
also working on a summary of mineral chemistry of the
howardite-eucrite-diogenite (HED) clan. The NAU Meteoritics Lab has accumulated
one of the most extensive collections of this clan, which is believed to
originate from the asteroid 4 Vesta, as part of our classification efforts.
Among the other meteorites we’ve studied previously are two lunar samples (NWA
032, NWA 773) and one from Mars (NWA 2046). NWA 773 is a rare lunar cumulate
olivine norite; NWA 2046 is the most primitive (magnesian) shergottite yet
recovered. See “Meteorite Classification Services” at the link above for more
details. I have also collaborated with archaeologist Kim Spurr of Navajo Nation
Archaeology Department, studying volcanic-ash tempered ceramics.
A.J. Irving, T.E. Bunch, S.M. Kuehner,
& J.H. Wittke, 2004, Petrology of Primitive Olivine-Orthopyroxene-Phyric
Shergottites NWA 2046 and NWA 1195: Analogies with Terrestrial Boninites and
Implications for Partial Melting of Hydrous Martian Mantle: 35th Lunar and
Planetary Science Conference Abstracts, no. 1444.
T.J. Fagan, G. J. Taylor, K. Keil, T.L.
Hicks, M. Killgore, T. E. Bunch, J. H. Wittke, D.W. Mittlefehldt, R. N.
Clayton, T. K. Mayeda, O. Eugster & S. Lorenzetti, 2003, Northwest Africa
773: Lunar Origin, Iron-Enrichment Trend, and Brecciation: Meteoritics and
Planetary Science 38:529-554.
T. J. Fagan, G. J. Taylor, K. Keil, T. E.
Bunch, J. H. Wittke, R. L. Korotev, B. L. Jolliff, J. J. Gillis, L.A. Haskin,
E. Jarosewich, R.N. Clayton, T. Mayeda, V. A. Fernandes, R. Burgess, G. Turner,
O. Eugster & S. Lorenzetti, 2002, Northwest Africa 032: Product of Lunar
Volcanism: Meteoritics and Planetary Science 37:371-394.
J. H. Wittke & R. F. Holm, 1996, The
association basanitic nephelinite-feldspar ijolite-nepheline monzosyenite at
House Mountain volcano, north-central Arizona: The Canadian Mineralogist