![]() Steens Mountain escarpment of eastern Oregon, looking east into the Alvord basin. High-volume flood-basalts of the Columbia River Basalt Group erupted at 17–16 Ma, marking full arrival the YHS plume from beneath the subducting slab, followed by the classic bimodal volcanism that defines the Yellowstone-Snake River Plain hotspot track from late Miocene to recent time. ![]() Early eruptions along this trend generated high-potassium volcanism, with coeval “adakite” volcanism above the hot plume center. As the YHS eventually broke through the slab it would produce a linear track of volcanic provinces that decreases in eruption age from the Oregon-Nevada border region through southern Idaho to Yellowstone National Park. The YHS was overridden by North America at this time and shielded beneath the subducting Farallon plate from 42 to 34 Ma. This generated the Siletzia oceanic plateau that accreted onto the Pacific Northwest coast at 50 Ma. We discuss evidence for a long-lived and robust YHS first manifested by early marine volcanism offshore of Washington and Oregon 56 million years ago (Ma). The energetic source appears to derive from a plume of hot material that extends well into the Earth’s interior to the core-mantle boundary at a depth of 2,900 km. The Yellowstone hotspot (YHS) is well-known for producing super-eruptions far more explosive than those of human experience, but less is known about the ultimate source of these eruptions and the longevity of the hotspot itself. You can unsubscribe from that list at any time, either by clicking “Unsubscribe” at the bottom of those e-mails or by contacting. By registering, your e-mail address will be added to our list for updates on upcoming Lunchtime Expedition and Draper After Dark speakers. If you prefer to join us online, you may register in advance via Zoom webinar: Īfter registering, you will receive a confirmation email containing information about joining the webinar. The in-person talk takes place in the Center’s Coe Auditorium, with a virtual option available. Join us for our June Lunchtime Expedition, The Case for a Long-Lived and Robust Yellowstone Hotspot, presented by Victor E. The Case for a Long-Lived and Robust Yellowstone Hotspot By Victor E.
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