The Kimama core: A 6.4 Ma record of volcanism, sedimentation, and magma petrogenesis on the Axial Volcanic High, Snake River Plain, ID

The Snake River Plain (SRP) is one of the youngest and best-preserved examples of continental hotspot volcanism, with a continuous record of volcanism that extends over 16 Ma to the present. As part of the Yellowstone-Snake River volcanic province, the Snake River records the migration of plume-tail volcanism from inception at the Bruneau-Jarbridge caldera complex at 12.6 Ma to its present locus, under the Yellowstone Plateau. Hotspot volcanic products on the Snake River Plain include rhyolite lavas and ignimbrites, minor coeval basalts, and an overlying veneer of younger basalts erupted from fissures and low shield volcanoes.;Although the eastern SRP has been the focus of scientific drilling in the past, the central SRP has received comparatively little attention. The Kimama core hole was drilled as part of Project Hotspot, the Snake River Scientific Drilling Project, which seeks to understand the long-term volcanic and sedimentalogical history of the SRP volcanic province. The central SRP is the hinge point between the older western SRP province and the younger eastern province, and represents a transition between Pleistocene bimodal volcanism and the Pleistocene through Holocene olivine tholeiite basaltic volcanism. It is the only part of the SRP that has not been scientifically drilled and cored to a significant depth. Investigations of subsurface stratigraphy in continental volcanic provinces such as the SRP-YP are limited by the limited depth and spatial distribution of cored wells. The Kimama core is a continuous record of basalt and minor sediment deposition.;Our investigation of the Kimama core reveals a dynamic relationship between magmatic systems, volcanic processes, and the topography of the SRP over the past ~6.5 Ma. The long-term volcanic history of the SRP, documented by magmatic flux and magma composition, demonstrates that magmatism is mantle plume-derived and does not represent melting of a shallow mid-ocean ridge basalt-source within the asthenosphere. Our investigation of the Kimama core, combined with new mantle tomography refutes non-plume models for the origin of the Snake River Plain volcanic province.