• Slide 1

    Experimental Geochemistry @ the University of Oregon

  • Slide 2

    Experimental Geochemistry @ the University of Oregon

  • Slide 3

    Experimental Geochemistry @ the University of Oregon

  • Slide 5

    Experimental Geochemistry @ the University of Oregon


I am an associate professor in the Department of Earth Sciences at the University of Oregon. My group designs new experimental methods and mathematical models to interpret isotopic and chemical variations in geologic materials. The lab projects we are working on include:

  • Sintering ash to better understand what happens in volcanic conduits
  • Growing calcite and aragonite crystals to better understand past climate
  • Growing quartz crystals to better understand what happens in fractures and fault zones

Our current field areas are:

  • Crater Lake National Park, OR
  • Bishop Tuff, CA
  • Butte porphyry-copper deposit in Butte, MT
  • Mono Craters volcanic field, CA
  • The Little Colorado River, AZ
  • Lake Abert, OR

Recent images



James Watkins

Associate Professor

Jim Palandri

Research Associate

Laurent Devrient

co-advised w/NIOZ

Ellen Olsen

5th year PhD student



Marisa Acosta

PhD 2020
Postdoc at UNIL

Erin Hoxsie

MSc 2018
Lab analyst at Pace Analytical

Madison Ball

MSc 2017
Data analyst in Portland

Evan Baker

MSc 2015
PhD student at Tufts

Eli Bloch

Postdoc 2014-2015
Postdoc at UNIL

Eamonn Needham

BSc 2019
PhD student at ASU

Molly Pickerel

BSc 2019
PhD student at UNLV


Carbonate paleoclimate records

The abundances of stable isotopes in carbonate minerals are widely used to infer paleo-environmental conditions. Oxygen isotopes, for example, record the temperature of carbonate formation. Although these types of proxies work in many settings, there are important details that need to be worked out to fully capitalize on stable isotope measurements. We are growing calcite and aragonite in the lab from aqueous solutions to figure out what environmental variables in addition to temperature are recorded in the oxygen, carbon, and clumped isotope composition of carbonates.

Volcanic textures

Crystal and bubble shapes in magma are sensitive to temperature, pressure, and magma ascent rate. We simulate volcanic conditions in the lab by heating/cooling and compressing/decompressing magma to figure out how textures in volcanic rocks are created by non-observable processes in the subsurface. The photo is a pumice created by undergraduate Eamonn Needham.

Non-equilibrium magma degassing

Bubbles are generally thought to grow as magma rises. Volatile concentration gradients around bubbles, however, show that bubbles can undergo cycles of growing and shrinking as a consequence of magma deformation. We are growing bubbles in the lab, sintering ash, and studying pyroclasts from volcanoes in Oregon and California to better understand what actually happens to volatiles when magma rises through the shallow crust.

Quartz growth from hydrothermal solutions

Magmatic-hydrothermal fluids in the crust transport and deposit ore metals in some settings, and in other settings, they feed hot water into high-temperature geothermal systems used to produce electricity. Exactly how minerals precipitate in these environments is not well understood because we cannot directly observe the processes. We are growing quartz crystals in the lab under controlled conditions to find ways of figuring out the temperature, depth and growth histories of quartz crystals in natural hydrothermal systems.

Crystal growth, diffusion, and radioactive decay

A key assumption in many geochronological studies is that minerals retain the parent and daughter nuclides throughout their existence. Diffusive separation of the parent and daughter isotopes, which can occur when a rock is subjected to reheating events or during the initial cooling of a rock, can give rise to apparent ages that can be too old or too young. We applied these principles to understand why Lu-Hf ages of eucrite meteorites from the asteroid Vesta appeared to (erroneously) pre-date the age of the solar system.

Isotope diffusion in solutions, minerals, and melts

The goal of stable isotope geochemistry is to interpret variations in isotopic abundances that are observed in nature. This requires an understanding of how isotopes are separated during diffusion, chemical reactions, and partitioning between phases. We are measuring small differences in the diffusivities of isotopes to figure out how cations diffuse in liquids and to predict where and when diffusion is responsible for stable isotope variations in nature.

Lots of other projects...

We're always going down new rabbit holes and undergrads are encouraged to participate. Current and past undergrads have worked on dendritic crystal growth, travertine formation, the Soret effect, magma decompression experiments, and ash sintering experiments. Many of the projects involve hands-on experience with high-temperature, high-pressure experimental apparatuses and high-tech instrumentation housed in the Lokey Lab.



  1. Hoxsie, E., Watkins, J., Gardner, J., and Befus, K., Ash sintering in the presence of a CO2-H2O vapor: Experiments and comparison to natural samples, for Bulletin of Volcanology.
  2. Giachetti, T., Trafton, K., Wiejaczka, J., Gardner, J., Watkins, J., Shea, T., and Wright, H., 201x, The products of primary magma fragmentation finally revealed by pumice agglomerates, in review.
  3. Watkins, J., and Antonelli, M., Beyond equilibrium: Kinetic isotope effects in high-temperature systems, Elements, in revision.
  4. Hudak, M., Bindeman, I., Watkins, J., and Lowenstern, J., Hydrogen isotope fractionation between volcanic glass and water vapor between 175 and 375°C, GCA, in review
  5. 2020

  6. Acosta, M., Reed, M. and Watkins, J., Textures of quartz-molybdenite veins in the Butte, Montana porphyry copper deposit indicate vein strain during deposit formation, American Mineralogist, in revision.
  7. Olsen, E. Watkins, J., and Devriendt, L., The influence of background electrolytes on the activity of carbonic anhydrase and δ18O of inorganic calcite. GCA, in revision.
  8. Metzger, E., Devriendt, L., Olsen, E., Watkins, J., Kaczmarek, K., Nehrke, G., de Nooijer, L., and Reichart, G.-J., Sodium incorporation into inorganic calcite and implications for the use of biogenic carbonates as a salinity proxy, GCA, resubmitted.
  9. Christensen, J., Watkins, J., DePaolo, D., Devriendt, L., Conrad, M., Voltolini, M., Brown, S., and Yang, W., Calcium, carbon, and oxygen isotope fractionation accompanying carbonate precipitation from high pH waters at The Cedars, CA, GCA, in press
  10. Watkins, J., Christensen, J., Ryerson, F., and DePaolo, D., 201x, Ca and K isotope fractionation by diffusion in molten silicates: Large concentration gradients are not required to induce large diffusive isotope effects, AGU Monograph chapter, in press.
  11. Acosta, M., Watkins, J., Reed, M., Donovan, J., and DePaolo, D., 2020, Ti-in-quartz: Evaluating kinetic effects in high temperature crystal growth experiments, Geochimica et Cosmochimica Acta, v. 149, p. 149-167. (pdf reprint)
  12. 2019

  13. Antonelli, M., Mittal, T., McCarthy, A., Tripoli, B., Watkins, J., and DePaolo, D., 2019, Ca isotopes indicated rapid disequilibrium crystal growth in volcanic and subvolcanic systems, PNAS. (pdf reprint)
  14. Gardner, J., Wadsworth, F., Llewllin, E., Watkins, J.M., and Coumans, J., 2019, Experiments and constraints on the origin of obsidian pyroclasts, Bulletin of Volcanology, 81:22. (pdf reprint)
  15. 2018

  16. Burgener, L., Huntington, K., Sletten, R., Watkins, J.M., Quade, J., and Hallet, B., 2018, Clumped isotope constraints on equilibrium formation and kinetic isotope effects in soil carbonates from freezing soils, Geochimica et Cosmochimica Acta, v. 235, p. 402-430. (pdf reprint)
  17. Myers, M., Wallace, P., Wilson, C., Watkins, J.M. and Liu, Y., 2018, Ascent rates of rhyolitic magma at the onset of three caldera forming eruptions, American Mineralogist, v. 103, p. 952-965. (pdf reprint)
  18. Gardner, J., Wadsworth, F., Llewellin, E., Watkins, J.M. and Coumans, J., 2018, Experimental sintering of ash at conduit conditions and implications for the longevity of tuffisites, Bulletin of Volcanology, v. 80(3), article 23. (pdf reprint)
  19. Bloch, E., Watkins, J.M. and Ganguly, J., 2018, Comment on "Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics” [Geochimica et Cosmochimica Acta 212 (2017) 303-323], Geochimica et Cosmochimica Acta, v. 230, p. 190-192. (pdf reprint)
  20. 2017

  21. Devriendt, L.S., Watkins, J.M. and McGregor, H.V., 2017, Oxygen isotope fractionations in the CaCO3-DIC-H2O system, Geochimica et Cosmochimica Acta, v. 214, p. 115-142. (pdf reprint)
  22. Saenger, C., Gabitov, R., Farmer, J., Watkins, J.M. and Stone, R., 2017, Linear correlations in bamboo coral δ13C and δ18O sampled by SIMS and micromill: Evaluating paleoceanographic potential and biomineralization mechanisms using δ11B and Δ47 variability, Chemical Geology, v. 454, p. 1-14 . (pdf reprint)
  23. Bloch, E., Watkins, J.., and Ganguly, J., 2017, Diffusion kinetics of lutetium in diopside and the effect of thermal metamorphism on Lu-Hf systematics in meteorites, Geochimica et Cosmochimica Acta, v. 204, p. 32-51. (pdf reprint)
  24. Gardner, J.E., Llewellin, E.W., Watkins, J.M. and Befus, K.S., 2017, Formation of obsidian pyroclasts by sintering of ash particles in the volcanic conduit, Earth and Planetary Science Letters, v. 459, p. 252-263. (pdf reprint)
  25. Watkins, J., Gardner, J.E., and Befus, K.S., 2017, Non-equilibrium degassing, regassing, and vapor fluxing in magma feeder systems, Geology, v. 45, no. 2, p. 183-186. (pdf reprint)
  26. Teng, F., Dauphas, N., and Watkins, J., 2017, Non-traditional stable isotopes: Retrospective and prospective, Reviews in Mineralogy and Geochemistry v. 82. (pdf reprint)
  27. Watkins, J., DePaolo, D., and Watson, E.B., 2017, Kinetic fractionation of non-traditional stable isotopes by diffusion and crystal growth reactions, Reviews in Mineralogy and Geochemistry v. 82. (pdf reprint)
  28. 2016

  29. Seligman, A., Bindeman, I., Watkins, J.., and Ross, A., 2016, Water in volcanic glass: From volcanic degassing to secondary hydration, Geochimica et Cosmochimica Acta, v. 191, p. 216-238. (pdf reprint)
  30. Saenger, C., and Watkins, J., 2016, A refined method for calculating paleotemperatures from linear correlations in bamboo coral carbon and oxygen isotopes, Paleoceanography, v. 31, p. 789-799. (pdf reprint)
  31. Gardner, J., Befus, K., Watkins, J., and Clow, T., 2016, Nucleation rates of spherulites in natural rhyolitic lava, American Mineralogist, v. 101, p. 2367-2376. (pdf reprint)
  32. Aster, A., Wallace, P., Moore, L., Watkins, J., Gazel, E., and Bodnar, R., 2016, Reconstructing CO2 concentrations in basaltic melt inclusions from mafic cinder cones using Raman analysis of vapor bubbles, Journal of Volcanology and Geothermal Research, v. 323, p. 148-162. (pdf reprint)
  33. 2015

  34. Watkins, J., and Hunt, J., 2015, A process-based model for non-equilibrium clumped isotope effects in carbonates, Earth and Planetary Science Letters, v. 432, p. 152-165. (pdf reprint)
  35. Befus, K.S., Watkins, J., Gardner, J., Richard, D., Befus, K.M., Miller, N., and Dingwell, D., 2015, Spherulites as in-situ recorders of thermal history in lava flows, Geology, v. 42, no. 7, p. 647-650. (pdf reprint)
  36. 2014

  37. Watkins, J., Hunt, J., Ryerson, F., and DePaolo, D., 2014, The influence of temperature, pH, and growth rate on the δ18O composition of inorganically precipitated calcite, Earth and Planetary Science Letters, v. 404, p. 332-343. (pdf reprint)
  38. Von Aulock, F., Kennedy, B., Schipper,I., Castro, J., Martin, D., Oze, C., Nichols, A., Watkins, J., Wallace, P., Puskar, L., Bégué, F., Tuffen, H., 2014, Advances in Fourier transform infrared spectroscopy of natural glasses: From sample preparation to data analysis, Lithos, v. 206-207, p. 52-64. (pdf reprint)
  39. Watkins, J., Liang, Y., Richter, F., Ryerson, F., and DePaolo, D., 2014, Diffusion of multi-isotopic species in molten silicates, Geochimica et Cosmochimica Acta, v. 139, p. 313-326 (pdf reprint)
  40. 2013

  41. Watkins, J., Nielsen, L., Ryerson, F., and DePaolo, D., 2013, The influence of kinetics on the oxygen isotope composition of calcium carbonate, Earth and Planetary Science Letters, v. 375, p. 349-360. (pdf reprint)
  42. Gardner, J., Befus, K., Watkins, J., Hesse, M., and Miller, N., 2012, Compositional gradients surrounding spherulites in obsidian and their relationship to spherulite growth and cooling, Bulletin of Volcanology. (pdf reprint)
  43. 2008-2012

  44. Watkins, J., Manga, M., and DePaolo, D., 2012, Bubble geobarometry: A record of pressure changes, degassing, and regassing at Mono Craters, California, Geology. (pdf reprint)
  45. Watkins, J., DePaolo, D., Ryerson, F., and Peterson, B., 2011, Influence of liquid structure on diffusive isotope separation in molten silicates and aqueous solutions, Geochimica et Cosmochimica Acta, v. 75, p. 3103-3118. (pdf reprint)
  46. Watkins, J., 2010, Elemental and isotopic separation by diffusion in geological liquids, Ph.D. Dissertation, University of California Berkeley.
  47. Watkins, J., DePaolo, D., Huber, C., and Ryerson, F., 2009, Liquid composition-dependence of calcium isotope fractionation during diffusion in molten silicates, Geochimica et Cosmochimica Acta, v. 73, p. 7341-7359. (pdf reprint)
  48. Richter, F., Watson, E., Mendybaev, R., Dauphas, N., Georg, B., Watkins, J., and Valley, J., 2009, Isotope fractionation of the major elements of molten basalt by chemical and thermal diffusion, Geochimica et Cosmochimica Acta, v. 73, p. 4250-4263. (pdf reprint)
  49. Huber, C., Watkins, J., and Manga, M., 2008, Steady shape of a miscible bubble rising below an inclined wall at low Reynolds numbers, European Journal of Fluid Mechanics B/Fluids, v. 28, p. 405-410. (pdf reprint)
  50. Watkins, J., Manga, M., Huber, C., and Martin, M., 2008, Diffusion-controlled spherulite growth inferred from H2O concentration profiles in obsidian, Contributions to Mineralogy and Petrology, v. 157, p. 163-172. (pdf reprint)


If you're trying to decide which graduate school you'd like to attend, here are some reasons why you should choose the University of Oregon in Eugene.

Experimental geochemistry @ UO

I'm looking for graduate students to join my group. If you're interested in attending graduate school at UO please send me an email with a copy of your CV and a statement of why you're interested in working with me. Our graduate student applicant pool is very competitive and I'm particularly interested in taking students that have ideas of what they'd like to work on and why we'd be a good fit. There are currently no funded postdoctoral positions availale but if you're interested in writing a proposal to come to Oregon please let me know.


We're a big department at 20 faculty members and 40 graduate students, but we're not too big. You'll still get regular attention from your advisor, have the chance to interact with all faculty members, and there's a healthy graduate community to support you in your research endeavors. Many of our recent graduates have gone on to prestigious postdocs at national institutions, such as the USGS, or to other top rated Earth science programs while others acquire faculty positions at schools throughout the US.


Eugene is a big-small town. You can find world class fly fishing along the Willamette river, rafting swimming or tubing on the McKenzie, golf in Eugene (Laurelwood) or any of the fine courses nearby (I like Diamond Woods and Tokatee). There are local farmers markets in Eugene on the weekends or you can go to the farm if you prefer. Oregon beer is legendary. You'll have the opportunity to choose from a dozen local breweries in town, or if beer doesn't suit your fancy, the Willamette Valley is up and coming a Pinot noir powerhouse, with several wineries within a few miles of town. For a good time, you can also check out the Oregon Country Fair, the Bach Festival, and Saturday market.


An hour drive west of Eugene, you'll find the breathtaking Oregon coast where you can dive, fish, surf, and eat local, all in a day trip. An hour to the east are the Cascades. You can see the Three Sisters volcanoes from Eugene and both downhill and cross country skiing are slightly over an hour away. Two hours north, you'll find Portland, OR. A beer, dub-step, and hipster mecca, you'll need to make a pilgrimage north at some point, if not for Portland itself, to ski above the clouds at Mt. Hood or tour the spectacular waterfalls of the Columbia River Gorge. Two plus hours south is Crater Lake National Park. You'll have your choice of stratovolcanoes, from Mt. Shasta in northern California, to Mt. St. Helens just north of the Oregon-Washinton border....there's plenty to climb and study. The Rogue, McKenzie, and Umpqua rivers are also fun to raft and most are available as day trips. If you like to rock climb, you'll find no shortage of places to do so (Smith rock, near Bend, OR, is well known as the place where sport climbing was invented).


James M. Watkins
Associate Professor
Department of Earth Sciences
1272 University of Oregon
Eugene, OR 97403
Office: Cascade 205A
Email: watkins4@uoregon.edu