Towards timescales of assimilation and magma mixing in the Large Igneous Province of Snake River Plain-Yellowstone, northwest United States

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The breath of magma diversities in the Snake River Plain and Yellowstone (SRP-Y) volcanic fields presents a unique opportunity to study the interaction of a hot-spot-related thermal anomaly with the continental crust and the subsequent development of magma reservoirs. As a reservoir forms, primitive magma batches induce crustal melting and assimilation, and mixing. Mixing caused by a recharge of a more primitive magma is expected to be accompanied by heating of the reservoir which may obstruct fractionation and thus to precede it. The SRP-Y holds the tale of this chemical process and therefore provides the pieces of the puzzle portraying the evolution of magmas. A series of tests is proposed to systematically characterize the evolution and importance of mixing during the lifetime of reservoirs fed by a hotspot. This work aims to (1) identify end members in the SRP, and (2) to characterize their physical (e.g., density, viscosity) and chemical (e.g., interstitial melt’s composition, volatile content) properties. In a second phase, this work will (3) assess the interaction between physical and chemical properties of the magmas involved in the SRP-Y systems; and (4) constrain changes in the timescale of assimilation and mingling in the SRP magma reservoirs.