Geodynamics of the Yellowstone hotspot and mantle plume: Seismic and GPS imaging, kinematics, and mantle flow

Abstract

The Yellowstone hotspot resulted from interaction of a mantle plume with the overriding North America plate highly modifying the lithosphere by magmatic-tectonic processes and producing the 17 Ma Yellowstone-Snake River Plain (YSRP) volcanic system. The accessibility of the YSRP has allowed largescale geophysical experiments to seismically image the hotspot and to evaluate its kinematic and dynamic properties using geodetic measurements. Tomography reveals a Yellowstone crustal magma body with 8-15% melt that is fed by an upper-mantle plume extending from 80 km to 660 km deep and tilting 60º west. Contemporary deformation of the Yellowstone caldera is dominated by SW-extension at up to ~3 mm/yr, a fourth of the total Basin-Range opening rate, but with superimposed volcanic uplift and subsidence at decade scales, averaging ~2 cm/yr and unprecedented caldera uplift from 2004-2008 at up to 7 cm/yr. Convection models reveal eastward upper-mantle flow beneath Yellowstone at relatively high rates of 5 cm/yr and opposite in direction to the overriding N. American Plate. This strong flow deflects the ascending plume melt into a tilted configuration, i.e., the plume is caught in a mantle "wind". Dynamic models of the Yellowstone plume revealed relatively low excess temperatures, up to 120°K, with up to 1.5% melt, properties consistent with a weak buoyancy flux of ~0.25 Mg/s. The flux is several times smaller than for oceanic plumes, but it produced a ~600-km wide topographic ~300-m high swell. Employing the plume-geometry we extrapolated the location of the Yellowstone mantle-source southwestward to its initial position at 17 million years beneath eastern Oregon and the southern edge of the LIP Columbia Plateau basalt field suggesting a common origin. Our model suggests that the original plume head rose vertically behind the subducting Juan de Fuca plate, but at ~12 Ma it lost the protection of the subducting plate and encountered cooler, thicker continental lithosphere and became affected by the eastward upper-mantle flow. Regionally, excess gravitation potential energy of the swell drives the SW motion of the YSRP lithosphere that becomes part of a general clockwise rotation pattern of intraplate western U.S. tectonism. Our models thus demonstrate that plume-plate processes of the YSRP have "continentalized" oceanic lithosphere enhancing intraplate extension and highly modifying topography, deep into the continental interior. Our results demonstrate that the dynamic properties of the Yellowstone hotspot deserved its recognition as a "window into the Earth's interior". JVGR

The Yellowstone magmatic system from the mantle plume to the upper crust

“…Assuming the mantle plume is the dominant heat source and perfectly transfers the heat into the lowermost crust, we can then use the excess temperature of the plume to assess the velocity reduction in the lower crust. Previous studies have suggested the excess temperature of the Yellowstone plume to be 55-120 K (2,46). Using this value together with the temperature coefficient of mafic granulite gives a VP decrease of 0.029-0.062 km/s, corresponding to a 0.4-0.9% velocity reduction.…”

Evidence for Cyclical Fractional Crystallization, Recharge, and Assimilation in Basalts of the Kimama Drill Core, Central Snake River Plain, Idaho: 5.5-Million-Years of Petrogenesis in a Mid-crustal Sill Complex

“…The Snake River Plain (SRP) of central Idaho is a manifestation of Yellowstone-Snake River Plain (YSRP) hotspot volcanism and contains intriguing evidence for mantle hotspot impingement on continental crust (Pierce and Morgan, 1992;Hanan et al, 2008;Shervais and Hanan, 2008;Smith et al, 2009;Jean et al, 2014). The region contains a record of continuous bimodal volcanism extending over 17 Ma Coble and Mahood, 2012;Henry et al, 2017) to the present, and documents the migration of timetransgressive rhyolitic volcanism from the Bruneau-Jarbidge volcanic center (circa 12 Ma) to its present location beneath the Yellowstone Plateau (Pierce and Morgan, 1992;Anders et al, 2009).…”

Temporal and Seasonal Variations of the Hot Spring Basin Hydrothermal System, Yellowstone National Park, USA

“…The eastern Hot Spring Basin hydrothermal system includes a hydrothermal explosion crater, some hydrothermal pools, a small pond and the uppermost reaches of Wrong Creek. A low-velocity, upper-mantle body or plume is the conduit for an ascending melt associated with the Yellowstone hotspot [16]. The plume's buoyancy produces a ~400-km wide and ~500 m topographic high centered on the Yellowstone Plateau.…”