James Leong

Research Website: https://sites.google.com/view/mageslab
My research aims to understand the nature and dynamics of water-gas-rock interaction, which is a major geological process that facilitates mass and chemical exchanges between the surface and deep Earth reservoirs. I integrate tools in petrology and mineralogy, aqueous and gas chemistry, and computational thermodynamics to investigate the consequences and implications of  water-gas-rock interactions on surface and groundwater chemistry, the redox state and habitability of rock-hosted environments on Earth and beyond, nutrient and critical element mobility in various Earth reservoirs, and CO2 sequestration strategies that can help mitigate global climate change.

Possible Thesis/Dissertation Topics

1. Carbon mineralization and critical element mobilization during alteration of ultramafic rocks.
2. Subsurface redox conditions informed by variably altered, low-temperature serpentinites.
3. Geochemistry of alkaline and other extreme aqueous environments.
4. Formation of reduced volatiles (e.g., H2, CH4) during water-rock interactions.
5. Element mobilization and carbon mineralization in subduction zones.
6. Habitability of extreme and subsurface rock-hosted environments on Earth and beyond.

Select Publications

Leong, J. A. M., de Obeso, J.C., Manning, C. E., Kelemen, P. B. (2023). Thermodynamic constraints on the fate of carbon mobilized from subducted sediments in the overlying mantle wedge. Earth and Planetary Science Letters 623, 118424. https://doi.org/10.1016/j.epsl.2023.118424

 
Leong, J. A. M., Nielsen, M., McQueen, N., Karolytė, R., Hillegonds, D. J., Ballentine, B., Darrah, T., McGillis, W., and Kelemen, P. B. (2023). H2 and CH4 outgassing rates in the Samail ophiolite, Oman: Implications for low-temperature, continental serpentinization rates. Geochimica et Cosmochimica Acta 347, 1–15. https://doi.org/10.1016/j.gca.2023.02.008

Ely, T., Leong, J. A. M., Canovas III, P. A., and Shock, E. L. (2023). Huge variation in H2 generation during seawater alteration of ultramafic rocks. Geochemistry, Geophysics, Geosystems 24, e2022GC010658. https://doi.org/10.1029/2022GC010658

Howells, A. E., Leong, J. A. M., Ely, T., Robinson, K., Santana, M., Elizinodo, S. E., Cox, A., Poret-Peterson, A., Krajmalnik-Brown, R., Shock, E. L. (2022). Energetically informed niche models of hydrogenotrophs detected in serpentinized fluids of the Samail ophiolite of Oman. Journal of Geophysical Research: Biogeosciences, 127, e2021JG006317. https://doi.org/10.1029/2021JG006317

Kelemen, P. B., de Obeso, J. C., Leong, J. A. M., Godard, M., Okazaki, K., Kotowski, A. J., Manning, C., Ellison, E. T., Menzel, M. D., Urai, J., Hirth, G., Rioux, M., Fritz D. S., Lafay, R., Beinlich, A., Coggon, J. A., Warsi, N. H., Matter, J., Teagle, D., Michibayashi, K., Takazawa, E., Sulaimani, Z. A., Harris, M., and the Oman Drilling Party (2022). Listvenite formation during mass transfer into the leading edge of the mantle wedge: Initial results from Oman Drilling Project Hole BT1B. Journal of Geophysical Research: Solid Earth, 127, e2021JB022352. https://doi.org/10.1029/2021JB022352

de Obeso, J. C., Kelemen, P. B., Leong, J. A. M., Menzel, M. D., Manning, C., Godard, M., Cai, Y., and Bolge, L. (2022). Deep sourced fluids for peridotite carbonation in the shallow mantle wedge of a fossil subduction zone: Sr and C isotope profiles of OmanDP Hole BT1B. Journal of Geophysical Research: Solid Earth, 126, e2021JB022704. https://doi.org/10.1029/2021JB022704

Leong, J. A. M., Ely, T., and Shock, E. L. (2021). Decreasing extents of Archean serpentinization contributed to the rise of an oxidized atmosphere. Nature Communications, 12, 7341. https://doi.org/10.1038/s41467-021-27589-7

 
Kelemen, P. B., Leong, J. A. M., de Obeso, J. C., Matter, J., Ellison, E. T., Templeton, A. S., Nothaft, D. B., Eslami, A., Evans, K., Godard, M., Coggon, J. A., Warsi, N. H., Pézard, P. Choe, S., Teagle, D., Michibayashi, K., Takazawa, E., Sulaimani, Z. A., and the Oman Drilling Party (2021). Ongoing alteration of mantle peridotite in the weathering horizon: Initial results from the Oman Drilling Project Multi-Borehole Observatory. Journal of Geophysical Research: Solid Earth, 126, e2021JB022729. https://doi.org/10.1029/2021JB022729

Leong, J. A. M., Howells, A. E., Robinson, K., Debes, V., Fecteau, K., Prapaipong, P., Cox A., and Shock, E. L. (2021). Thermodynamic predictions vs measured fluid chemistry: Lessons from low-temperature peridotite-hosted fluids in the Samail ophiolite, Oman. Journal of Geophysical Research: Solid Earth, 126, e2020JB020756. https://doi.org/10.1029/2020JB020756

 
Leong, J. A. M., and Shock, E. L. (2020). Thermodynamic constraints on the geochemistry of low-temperature, continental, serpentinization-generated fluids. American Journal of Science, 320(3), 185–235. https://doi.org/10.2475/03.2020.01

Dick, H. J. B., MacLeod, C. J., Blum, P., Abe, N., Blackman, D. K., Bowles, J. A., Cheadle, M. J., Cho, K., Ciazela, J., Deans, J. R., Edgcomb, V. P., Ferrando, C., France, L., Ghosh, B., Ildefonse, B., John, B., Kendrick, M. A., Koepke, J., Leong, J. A. M., Liu, C., Ma, Q., Morishita, T., Morris, A., Natland, J. H., Nozaka, T., Pluemper, O., Sanfilippo, A., Sylvan, J.B., Tivey, M.A., Tribuzio, R., and Viegas, G. (2019). Dynamic accretion beneath a slow-spreading ridge segment: IODP Hole 1473A and the Atlantis Bank Oceanic Core Complex. Journal of Geophysical Research: Solid Earth, 124(12), 12631–12659. https://doi.org/10.1029/2018JB016858