Discovery of two new super-eruptions from the Yellowstone hotspot: Is Yellowstone hotspot waning?

Super-eruptions are amongst the most extreme events to affect the Earth’s surface, but too few examples are known to assess their global role in crustal processes and environmental impact. We demonstrate a robust approach to recognise them at one of the best-preserved intraplate large igneous provinces, leading to the discovery of two new super-eruptions. Each generated huge and unusually hot pyroclastic density currents that sterilised extensive tracts of Idaho and Nevada, USA. The ~8.99 Ma McMullen Creek eruption was magnitude 8.6, larger than the last two major eruptions at Yellowstone. It exceeds 1,700 km³, covering ≥12,000 km². The ~8.72 Ma Grey’s Landing eruption was even larger, at magnitude of 8.8 and volume of ³2,800 km³. It covers ≥23,000 km² and is the largest and hottest documented eruption from the Yellowstone hotspot. The discoveries show the effectiveness of distinguishing and tracing vast deposit sheets by combining trace-element chemistry and mineral compositions with field and paleomagnetic characterisation. This approach should lead to more discoveries and size estimates, here and at other provinces. It has increased the number of known super-eruptions from Yellowstone hotspot, shows that the temporal framework of the magmatic province needs revision, and suggests the hotspot may be waning.