18-19. The hazards and dynamics associated with deglaciation of the Yellowstone Plateau Volcanic Field: tectonics, magmatism, hydrothermal activity and landscape evolution

There is increasing evidence from the analyses of global datasets that the last deglaciation triggered a significant increase in volcanic activity. Yet, many aspects linking ice recession and enhanced volcanic activity are poorly understood. For example, how quickly do volcanic systems react to unloading of ice? Why do eruptions take place in some volcanoes but not in others following ice retreat? What was the response of hydrothermal systems to deglaciation? In Yellowstone, magma eruption was not associated with the last deglaciation. In fact, the last time rhyolitic magma reached the surface at Yellowstone was ~72,000 years ago. Recession of the most recent ice cap (Pinedale glaciation), however, had a profound impact in shaping the landscape of the Yellowstone Plateau. Patterns and processes of deglaciation dictated the distribution of many geological and hydrothermal features in Yellowstone, including some of the most significant icons that draw millions of visitors to the national park every year. These include among others, the Grand Canyon of the Yellowstone River, most of the lakes in the park, the major thermal basins, and large hydrothermal explosion craters. The postglacial Yellowstone Plateau exhibits dramatic unrest at multiple spatial and temporal scales that may reflect a combination of processes, including magmatism, tectonics, and climate. This unrest is manifested by abundant seismicity, episodes of uplift and subsidence that vary across temporal and spatial scales, and over 10,000 active hydrothermal features. Large hydrothermal explosions on the Yellowstone Plateau took place during the waning stages of the Pinedale glaciation, perhaps in response to substantial pressure reduction and extensive boiling in the hydrothermal system. Earthquakes are also among the most commonly recurring hazards, and some of the regional faults that bound the Yellowstone Plateau have produced large-magnitude (M>7) earthquakes. However, information on the timing, recurrence, and magnitudes of pre-instrumental large earthquakes is completely lacking even though it is very likely that deglaciation has significantly impacted earthquake occurrence rates and deformation. Whereas instrumental records collected from the Yellowstone Plateau since the 1970s have shown abundant activity at multiple spatial and temporal scales, records of hydrothermal explosions, large earthquakes and extensive thermal activity dating back to the last deglaciation are incomplete, or in some cases, completely lacking despite their significance for assessing the hazards.

We seek a Mendenhall Postdoctoral Fellow to provide a better understanding of the processes modulating Yellowstone’s landforms following glacial unloading, and to examine the interplay between magmatism, tectonics, climate, hydrothermal activity, and the geomorphic processes that have shaped the Yellowstone Plateau. Various applicable dating methods will be applied to provide constraints on the onset of hydrothermal activity, the timing of explosion crater formation, fault rupture history and slip rates, and/or adjustments of drainage systems, which often have volcano-tectonic origins. Available and planned lidar and satellite-based remote sensing data will be processed in combination with other datasets. The Fellow will be encouraged to conduct independent research and will be given ample latitude to pursue their own original ideas, using expertise that aligns with the overarching goals of the project. It is expected that a successful fellowship will provide an improved understanding of the many hazards posed by the very active Yellowstone magmatic-hydrothermal system, which in turn will aid with mitigating risks to park visitors, employees, resources and infrastructure.

Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.

References: 

Christiansen, R.L. and others, 2007. Preliminary assessment of volcanic and hydrothermal hazards in Yellowstone National Park and vicinity. U.S. Geol. Survey Open-File Report, 2007-1071, 94 pp, https://pubs.usgs.gov/of/2007/1071/.

Hurwitz, S. and Lowenstern, J.B., 2014. Dynamics of the Yellowstone hydrothermal system. Reviews of Geophysics, 52, 375-411.

Licciardi, J.M. and Pierce, K.L., 2018. History and dynamics of the Greater Yellowstone Glacial System during the last two glaciations. Quaternary Science Reviews, 200, 1-33.

Meyer, G.A., Wells, S.G. and Timothy Jull, A.J., 1995. Fire and alluvial chronology in Yellowstone National Park: climatic and intrinsic controls on Holocene geomorphic processes. Geological Society of America Bulletin, 107, 1211-1230.

Morgan, L.A., Shanks, W.C. and Pierce, K.L., 2009. Hydrothermal processes above the Yellowstone magma chamber: Large hydrothermal systems and large hydrothermal explosions. Geological Society of America Special Publication, 459, 1-95, https://doi.org/10.1130/SPE459.

Pierce, K.L., Cannon, K.P., Meyer, G.A., Trebesch, M.J., and Watts, R., 2002. Post-glacial inflation-deflation cycles, tilting and faulting in the Yellowstone Caldera based on Yellowstone Lake shorelines. U.S. Geological Survey Open-File Report, 02-0142, 61 pp., https://pubs.usgs.gov/of/2002/ofr-02-0142/.

Proposed Duty Station: Menlo Park, CA

Areas of PhD: Geomorphology, neotectonics, Quaternary geochronology, structural geology or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet the qualifications for Research Geologist. 

(This type of research is performed by those who have backgrounds for the occupations stated above.  However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)

Human Resources Office Contact: Audrey Tsujita, 916-278-9395, atsujita@usgs.gov