Professor, Geology Program Director

Office: 541-737-9350

Burt Hall

Burt Hall 250

2651 SW Orchard Avenue

2651 SW Orchard Avenue
Corvallis, OR 97331

Profile Field Tabs

Brief Research Interests: 

Igneous petrology, isotope geochemistry, electron probe microscopy



Igneous petrology, Isotope geochemistry, Electron probe microscopy
Electron Microprobe Laboratory

Research Interests

  1. Use of compositional variations and in situ Sr-isotopes in plagioclase feldspars in arc rocks to trace the effects of magma mixing and crustal contamination.
  2. Use of textural and geochemical information of plagioclase megacrysts and phenocrysts (and contained melt inclusions) in plagioclase ultraphyric basalts (PUB) and other plagioclase-bearing lavas to study and constrain processes that modify primary mantle-generation basalt compositions during crustal melt transport and residence in mid ocean ridges (MOR)
  3. Use of major- and trace-element diffusional profiles in mineral phases to determine the time scales of magma mixing processes occurring in sub-volcanic reservoirs.
  4. Use of U-series disequilibria (U, Th, Pa, Ra) in whole rocks and minerals to decipher the sources of slab-derived components in arc magmas, and the time scales and character of melting processes within the mantle wedge beneath ocean islands and continental arcs.

Current Research

  1. Phase thermometry (Ti in quartz) and its relationship to plutonic themal histories.
  2. Zircons and their associated trace element compositions measured via EMP techniques.
  3. Volcanic shard major- and trace-element compositions and their correlation with SW Japan Neogene eruptions.


B.S. Geology, California State University , Northridge , CA , USA, 1991
Ph.D. Geochemistry, University of California, Los Angeles, CA, USA, 1999


GEO315 - Petrology- Earth Materials II

OC528 - Microprobe Analysis 

OC668 - Theoretical Petrology

Feature Story

Coring the deep blue sea: Frank Tepley digs deep to understand underwater volcano (June, 2019)


Rowe, M. C., Tepley, F.J., III (2016) Origin and petrogenetic implications of anomalous olivine from a Cascade forearc basalt. American Mineralogist 101, 1807-1819.

Ustunisik, G., Loewen, M.W., Nielsen, R.L., Tepley, F.J., III (2016) Interpretation of the provenance of small scale heterogeneity as documented in a single eruptive unit from Mt. Jefferson, Central Oregon Cascades. Geochemistry Geophysics Geosystems DOI:10.1002/2016GC006297.

Norling, B., Rowe, M., Chambefort, I., Tepley, F.J., III, Morrow, S. (2016) Volatile behavior and trace metal transport in the magmatic-geothermal system at Pūtauaki (Mt. Edgecumbe), New Zealand. Journal of Volcanology and Geothermal Research 318, 27-44.

Arculus, R. J., and Science Team of IODP Expedition 351 (2015) A record of spontaneous subduction initiation in the Izu-Bonin-Mariana arc. Nature Geoscience, doi:10.1038/NGEO2515

Burns, D.H., de Silva, S.L., Tepley, F.J., III, Schmitt, A.K., Loewen, M.W. (2015) Recording the transition from flare-up to steady-state arc magmatism at the Purico–Chascon volcanic complex, northern Chile. Earth and Planetary Science Letters 422, 75–86.

Parsapoor, A., Khalili, M., Tepley, F.J., III, Maghami, M. (2015) Mineral chemistry and isotopic composition of magmatic, re-equilibrated and hydrothermal biotites from Darreh-Zar porphyry copper deposit, Kerman (Southeast of Iran). Ore Geology Reviews 66, 200-218.

Tepley, F.J., III, de Silva, S.L., Salas, G. (2013) Magma dynamics and petrologic evolution leading to the VEI 5 2000 B.P. eruption of El Misti Volcano, Southern Peru. Journal of Petrology, 54, 2033-2065.

Lange, A.E., Nielsen, R.L., Tepley, F.J. III, Kent, A.J.R. (2013) The petrogenesis of plagioclase-phyric basalts at mid-ocean ridges, Geochem Geophys Geosys. 14, #8; doi: 10.1002/ggge.20207

Lange, A., Nielsen, R.L., Tepley, F.J., III, Kent, A. (2012) Diverse Sr isotope signatures preserved in mid-oceanic-ridge basalt plagioclase. Geology, doi: 10.1130/G33739.1

Walker, B.A., Jr., Klemetti, E.W., Grunder, A.L., Dilles, J.H., Tepley, F.J., III, Giles, D. (2012). Crystal reaming during the assembly, maturation, and waning of an eleven-million-year crustal magma cycle: thermobarometry of the Aucanquilcha Volcanic Cluster. Contributions to Mineralogy and Petrology, doi:10.1007/s00410-012-0829-2

Adams, D.T., Nielsen, R.L., Kent, A.J.R., Tepley, F.J., III (2011) Origin of minor and trace element compositional diversity in anorthitic feldspar phenocrysts and melt inclusions from the Juan de Fuca Ridge, Geochem. Geophys. Geosyst., 12, Q12T11, doi:10.1029/2011GC003778.

Tepley, F.J., III, Lundstrom, C.C., McDonough, W.F., Thompson, A., (2010) Trace Element Partitioning Between High An Plagioclase and Basaltic and Basaltic Andesite Melts at 1 Atmosphere Pressure. Lithos 118, 82-94.

Ramos, F.C. & Tepley, F.J., III (2008). Inter- and Intra-Crystalline Isotopic Disequilibria: Techniques and Applications, Reviews in Mineralogy and Geochemistry, 69, 403-444.

Davidson, J.P., Font, L., Charlier, B.L.A., & Tepley, F. J., III (2008) Mineral-scale Sr isotope variation in plutonic rocks – a tool for unraveling the evolution of magma systems, Trans. Roy. Soc.  Edinburgh, 97, 357-367.

Tepley, F.J., III, Lundstrom, C. C., Gill, J., & Williams, R. (2006). U-Th-Ra disequilibria and the time scale of fluid transfer and andesite differentiation at Arenal Volcano, Costa Rica (1968-2003). Journal of Volcanology and Geothermal Research, 157, 147-165.

Lundstrom, C.C., Tepley, F.J., III (2006). Investigating the origin of anorthitic plagioclase through a combined observational-experimental approach. Journal of Volcanology and Geothermal Research, 157, 202-221.

Reagan, M., Tepley, F.J., III, Gill, J.B., Wortel, M., Garrison, J. (2006). Timescales of degassing and crystallization implied by 210Po-210Pb-226Ra disequilibria for andesitic lavas erupted from Arenal volcano. Journal of Volcanology and Geothermal Research, 157, 135-146.

Ryder, C.H., Gill, J.B., Tepley, F.J., III, Ramos, F., Reagan, M. (2006). Closed to open differentiation at Arenal Volcano (1968-2003). Journal of Volcanology and Geothermal Research, 157, 75-93.

Reagan, M., Tepley, F.J., III, Gill, J., Wortel, M. & Hartman, B. (2005) Rapid time scales of basalt to andesite differentiation at Anatahan volcano, Mariana Islands, Journal of Volcanology and Geothermal Research, 146, 171-183.

Tepley, F.J., III, LundstromC. C., Sims, K. W. W., & HékinianR. (2003). U-series disequilibria in MORB from the Garrett Transform and implications for mantle melting. Earth and Planetary Science Letters, 223, 79-97.

Tepley, F.J., III, & Davidson, J. P. (2003). Mineral-scale Sr-isotope constraints on magma evolution and magma chamber dynamics in the Rum layered intrusion, Scotland. Contributions to Mineralogy and Petrology, 145, 628-641.

Perini, G., Tepley, F.J., III, Davidson, J.P. & Conticelli, S. (2003). The origin of K-feldspar megacrysts hosted in alkaline potassic rocks from central Italy: a track for low-pressure processes in mafic magmas. Lithos, 66, 223-240.

Davidson, J.P., Tepley, F.J., III, Palacz, Z. & Meffan-Main, S. (2001). Magma recharge, contamination and residence times revealed by in situ laser ablation isotopic analysis of feldspar in volcanic rocks. Earth and Planetary Science Letters, 184, 427-442.

Tepley, F.J., III, Davidson, J.P., Tilling, R.I. & Arth, J.G. (2000). Magma mixing, recharge, and eruption histories recorded in plagioclase phenocrysts from El Chichón Volcano, Mexico. Journal of Petrology, 41, 1397-1411.

Tepley, F.J., III, Davidson, J. P. & Clynne, M. A. (1999). Magmatic interactions as recorded in plagioclase phenocrysts of Chaos Crags, Lassen Volcanic Center, California. Journal of Petrology, 40, 787-806.

Davidson, J. P., Tepley, F.J., III & Knesel, K. (1998). Isotopic fingerprinting may provide insights into evolution of magmatic systems. Eos, Transactions79.

Davidson, J. P. & Tepley, F.J., III (1997). Recharge in volcanic systems: evidence from isotopic profiles of phenocrysts. Science, 275, 826-829.