Prof. Philip Janney
Igneous and mantle petrology, cosmochemistry
Department of Geological Sciences
Ph: +27 (0)21 650 2929
Fax: +27 (0)21 650 3783
My research involves the application of elemental, radiogenic isotope and "non-traditional" stable isotope techniques to understand the geochemical evolution of the Earth’s mantle and crust, This is mainly done through the analysis of mantle xenoliths and igneous rocks formed at intraplate settings and mid-ocean ridges. I am also interested in using the above techniques to investigate the environmental conditions and formation history of planets in the early Solar System. Current research projects include:
•The use of ultramafic alkaline igneous rocks (kimberlites, olivine melilitites, lamprophyres) and carbonatites to understand the nature of lithosphere-asthenosphere interactions and the geochemical evolution of the continental lithospheric mantle.
•Investigation of the petrology and geochemistry of southern African off-craton peridotite mantle xenoliths to extend the record of southern African continental evolution into the Proterozoic and to better understand the geochemical differences between Archaean and Proterozoic lithospheric mantle.
•Studies of the interaction between the continental lithospheric mantle and melts and fluids through the analysis of megacrysts and metasomatic xenoliths in kimberlites.
Williams, C. D., Ushikubo, T., Janney, P.E., Kita, N.T., Hervig, R.L., Bullock, E.S., Hines, R.R., MacPherson, G. J., Mendybaev, R. A., Richter, F. M., Wadhwa, M. (2017) Thermal and chemical evolution of the early Solar System: Part I - Petrology, mineral chemistry, and isotopic composition of Allende FUN CAI CMS-1, Geochimica et Cosmochimica Acta 201, 25-48.
Williams, C.D., Janney P.E., Hines, R.R., Wadhwa M. (2016) Precise titanium isotope compositions of refractory inclusions in the Allende CV3 chondrite by LA-MC-ICPMS, Chemical Geology 436, 1-10.
Wainwright, A.N., Luguet, A., Schreiber, A., Fonseca, R.O.C., Nowell, G.M., Lorand, J.-P., Wirth, R., Janney, P.E. (2016) Nanoscale variations in 187Os isotopic composition and HSE systematics in a Bultfontein peridotite, Earth and Planetary Science Letters 447, 60-71
Davis, A.M., Richter, F.M., Mendybaev, R.A., Janney, P.E., Wadhwa, M., McKeegan, K.D. (2015) Isotopic mass fractionation laws for magnesium and their effects on 26Al-26Mg systematics in solar system materials, Geochimica et Cosmochimica Acta, 158, 245-261.
Day, J.M.D., Peters, B.J., Janney, P.E. (2014) Oxygen isotope systematics of South African olivine melilitites and implications for HIMU mantle reservoirs, Lithos 202, 76-84.
Mendybaev, R.A., Richter, F.M., Georg, R.B., Janney, P.E., Spicuzza, M.J., Davis, A.M., Valley, J.W. (2013) Experimental evaporation of Mg- and Si-rich melts: Implications for the origin and evolution of FUN CAIs. Geochimica et Cosmochimica Acta 123, 368-384.
Janney, P. E., Richter, F. M., Mendybaev, R. A., Wadhwa, M., Georg, R. B., Watson, E. B. & Hines, R. R. (2011) Matrix effects in the analysis of Mg and Si isotope ratios in natural and synthetic glasses by laser ablation-multicollector ICPMS: A comparison of single- and double-focusing mass spectrometers. Chemical Geology 281, 26-40.
Brennecka, G. A., Weyer, S., Wadhwa, M., Janney, P. E., Zipfel, J. & Anbar, A. D. (2010). 238U/235U Variations in Meteorites: Extant 247Cm and Implications for Pb-Pb Dating. Science 327, 449-451.
Janney, P. E., Shirey, S. B., Carlson, R. W., Pearson, D. G., Bell, D. R., le Roex, A. P., Ishikawa, A., Nixon, P. H. & Boyd, F. R. (2010) Age, composition and thermal characteristics of South African off-craton mantle lithosphere: evidence for a multi-stage history. Journal of Petrology 51, 1849-1890.
MacPherson, G. J., Bullock, E. S., Janney, P. E., Kita, N. T., Ushikubo, T., Davis, A. M., Wadhwa, M. & Krot, A. N. (2010) Early solar nebula condensates with canonical, not supracanonical, initial 26Al/27Al ratios. Astrophysical Journal 711, L117-L121.
Spivak-Birndorf, L., Wadhwa, M., Janney, P. (2009) 26Al-26Mg systematics in D’Orbigny and Sahara 99555 angrites: implications for high-resolution chronology using extinct chronometers, Geochimica et Cosmochimica Acta 73 5202-5211.
- PhD University of California, San Diego-Scripps Institution of Oceanography, 1996
- BSc University of New Hampshire, 1988
- Senior Lecturer, University of Cape Town, Department of Geological Sciences, 2012-
- Associate Research Scientist, Arizona State University, Center for Meteorite Studies, 2006-2012
- Isotope Geochemistry Laboratory Manager, Field Museum of Natural History, 2000-2006
- Postdoctoral Research Associate, Carnegie Institution of Washington-DTM, 1998-2000
- Postdoctoral Research Geologist, UC-San Diego, Scripps Institution of Oceanography, 1997-1998
- Postdoctoral Student, University of Cape Town, Department of Geological Sciences, 1996-1997
- American Geophysical Union
- Geochemical Society
- Meteoritical Society
- Geological Society of South Africa