Collaborative Research: Links Between Magma Source Characteristics, Shallow Plumbing, and Eruptive Styles in Mafic Intraplate Volcanic Fields (Lunar Crater Volcanic Field, Nevada)
Valentine, Greg Principal Investigator
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Intellectual merit. Volcanoes that form in intraplate fields, although small and (mainly) monogenetic, result from eruptive phenomena ranging from quiet effusion of lava to relatively explosive Strombolian activity and, if external water interacts with ascending magma, hydrovolcanic activity. The generation and eruption of magmas in relatively small batches over dispersed areas, often with evidence for direct ascent from the upper mantle to the surface, suggests a driving process that is hybrid between strong hotspot-style mantle upwelling and scattered pockets of incipient melt that are passively mobilized by tectonic deformation (high- and low-magma flux end members of volcanic fields, respectively). Integrated approaches involving physical volcanology, petrology, and geochemistry can provide important insights into these processes and the links between magma dynamics at depth and eruption processes on the surface. The lack of long-lived crustal magma reservoirs) allows investigation of the influences of deep magma source(s) and shallow plumbing systems on eruption styles. It is hypothesized that eruption style is influenced by physical and chemical characteristics of magma sources. To test this hypothesis comprehensive data will be integrated from the well-exposed Lunar Crater Volcanic Field (central Nevada). Direct studies of eruptive facies, of exposed shallow conduits (at older, eroded volcanoes), and of abundant mantle xenoliths will provide insights into the magma sources and ascent processes. Existing data on broad geochemicsl trends and age relationships will be integrated with new EarthScope seismic tomography data to provide a framework for understanding: (1) the interplay between pre-existing structure, topography, and vent location; (2) shallow plumbing geometries; (3) shallow controls on magmatic eruption styles, including relationships between eruption style, clast texture and shape, volatile content, and mineral chemistry; (4) spatial and temporal variations in magma sources and magma differentiation processes at individual volcanoes and across the field as a whole; (5) depth of melting and volatile contents of parent magmas; and (6) correspondence between volcano location, melting depths, and upper mantle seismic structure. Broader impacts. This work will support improvements in volcanic risk assessment, both in terms of the probability (volcano timing and location) of future events and in terms of their consequences (related to eruption processes). The project will also support the training of three Ph.D. students (two of whom are female minorities) and will have a component of international collaboration with the volcanology and geochemistry group at the Universidad Autónoma de México. The proposing team is in communication both with the Shoshone Tribe (Duckwater Reservation) and the Bureau of Land Management so that we can share our results with them and (through BLM) with the public.