Guillaume Girard

Research

Interests

• Timescales and dynamics of magmatic processes including magma generation, storage, ascent and degassing, from dormant long-lived volcanic systems (e.g., Yellowstone), to quasi-continuously erupting ‘open-conduit’ volcanoes (e.g., Kilauea).
• Exploring the connections between volcanoes and the un-erupted parts of continental magmatic systems, batholiths and crystal mushes.
• Using modern micro-analytical techniques to answer these questions, primarily through high-spatial resolution and high-precision laser-ablation ICP-MS of volcanic glasses and crystals.

Activities

• Improvement of the department’s laser-ablation ICP-MS analytical facility, to serve the broad needs of faculty members and their graduate students across our department and beyond, at NIU and elsewhere.
• Development of analytical methods on the department’s new Shimadzu Lab Center 1800 XRF spectrometer, to be complementary to the LA-ICP-MS.
• Exploring the longevity and complexity of magma sources and crystal mushes at Yellowstone, through mineral-melt equilibrium modeling and chemical zoning of crystals in lava flows.

Selected Publications

Girard G., Reagan M.K., Sims K.W.W., Thornber C.R., Waters C.L., Phillips E.H. (2017). ²³⁸U-²³⁰Th-²²⁶Ra-²¹⁰Pb-²¹⁰Po disequilibria constraints on magma generation, ascent, and degassing during the ongoing eruption of Kilauea, Journal of Petrology, 58(6), 1199-1226, doi: 10.1093/petrology/egx051

Girard G., Stix J. (2012). Future volcanism at Yellowstone caldera: insights from geochemistry of young volcanic units and monitoring of volcanic unrest, GSA Today, 22(9), 4-10, doi: 10.1130/GSATG143A.1

Girard G., Stix J. (2010). Rapid extraction of discrete magma batches from a large differentiating magma chamber: the Central Plateau Member rhyolites, Yellowstone Caldera, Wyoming, Contributions to Mineralogy and Petrology, 160, 441-465, doi:10.1007/s00410-009-0487-1

Girard G., Stix J. (2009a). Buoyant replenishment in silicic magma reservoirs: experimental approach and implications for magma dynamics, crystal mush remobilization and eruption, Journal of Geophysical Research, 114, B08203, doi:10.1029/2008JB005791

Girard G., Stix J. (2009b). Magma recharge and crystal mush rejuvenation associated with early post-collapse Upper Basin Member rhyolites, Yellowstone caldera, Wyoming, Journal of Petrology, 50(11), 2095-2125, doi:10.1093/petrology/egp070

Girard G., van Wyk de Vries, B. (2005). The Managua Graben and Las Sierras-Masaya volcanic complex (Nicaragua); pull-apart localization by an intrusive complex : Results from analogue modeling, Journal of Volcanology and Geothermal Research, 144, 37-57, doi: 10.1016/j.jvolgeores.2004.11.016

Chiasera, B., Rooney, T.O., Girard, G., Yirgu, G., Grosfils, E., Ayalew, D., Mohr, P., Zimbelman, J., Ramsey, M. (2018). Magmatically assisted off-rift extension—The case for broadly distributed strain accommodation: Geosphere, 14, doi: 10.1130/GES01615.1.

Trestrail K.R., Rooney T.O., Girard G., Svoboda C., Yirgu G., Ayalew D., Kappelman J. (2017). Sub-continental lithospheric mantle deformation in the Yerer-Tullu Wellel volcanotectonic lineament: a study of peridotite xenoliths, Chemical Geology, 455, 249-263, doi:10.1016/j.chemgeo.2016.10.013

Rooney T.O., Lavigne A., Svoboda C., Girard G., Yirgu G., Ayalew D., Kappelman J. (2017). The making of an underplate: Pyroxenites from the Ethiopian lithosphere, Chemical Geology, 455, 264-281, doi:10.1016/j.chemgeo.2016.09.011

Reagan M.K., McClelland W.C., Girard G., Goff K.R., Peate D.W., Ohara Y., Stern R.J. (2013). The geology of the southern Mariana fore-arc crust: Implications for the scale of Eocene volcanism in the western Pacific, Earth and Planetary Science Letters, 380, 41-51, doi:10.1016/j.epsl.2013.08.013

Ribeiro J.M., Stern R.J., Martinez F., Ishizuka O., Merle S.G., Kelley K., Anthony E.Y., Ren M., Ohara Y., Reagan M.K., Girard G., Bloomer S. (2013). Geodynamic evolution of a forearc rift in the Southernmost Mariana Arc, Island Arc, 2013, doi:10.1111/iar.12039

Turner M.B., Reagan M.K., Turner S.P., Sparks R.S.J., Handley H.K., Girard G., Suh C.E. (2013). Timescales of magma degassing — Insights from U-series disequilibria, Mount Cameroon, West Africa, Journal of Volcanology and Geothermal Research, 262, 38-46, doi:10.1016/j.jvolgeores.2013.06.003

Waters C.L., Sims K.W.W., Klein E.M., White S.M., Reagan M.K., Girard G. (2013). Sill to surface: linking young off-axis volcanism with subsurface melt at the overlapping spreading center at 9°03’N East Pacific Rise, Earth and Planetary Science Letters, 369, 59-70, doi:10.1016/j.epsl.2013.03.006

Ohara Y., Reagan M.K., Fujikura K., Watanabe H., Michibayashi K., Ishii T., Stern R.J., Pujana I., Martinez F., Girard G., et al. (2012). A serpentinite-hosted ecosystem in the Southern Mariana Forearc, PNAS 109:2831-2835, doi:10.1073/pnas.1112005109 

Selected Conference Abstracts

Girard G. (2019) Simple Mineralogy; Complex Message: Phenocrysts vs. Antecrysts in Yellowstone Central Plateau Rhyolites, Insights from Sanidine Trace Element Geochemistry, IUGG General Assembly, Montreal, Canada, July 9-17.

Girard G. (2017) Complex crystal populations in lava flows erupted in the early stages after caldera collapse at Yellowstone: implications for magma chamber composition and dynamics, IAVCEI General Assembly, Portland, Oregon, USA, August 18-22.

Girard, G., Stremtan, C. (2017). Fused bulk rock powder major and trace element analysis by LA-ICP-MS: a comparative study of 213 nm and 193 nm laser performance, 2^nd North American Workshop on Laser Ablation, Austin, Texas, USA, May 23-25.

Girard, G. (2016a). A method for simultaneous quantitative analysis of major and trace elements in minerals by Laser Ablation ICP-MS, 13^th European Workshop on Laser Ablation, Ljubljana, Slovenia, July 12-15.

Girard, G. (2016b). Small crystals, big implications: glomerocrysts and their possible connections to large silicic magma reservoirs. Examples from Yellowstone rhyolite lavas, EOS, Transactions, AGU Fall Meet. Suppl.

Girard G., Rooney T.O. (2013). Laser-ablation ICP-MS as a tool for whole rock trace element analyses on fused powders, EOS, Transactions, AGU Fall Meet. Suppl. V53F-2789