Ancient super-eruptions in Yellowstone Hotspot track ‘significantly larger’ than expected

Posted by ap507 at Mar 24, 2016 10:45 AM |
International team led by Leicester report 12 giant eruptions around the Snake River Plain in the United States between 8 and 12 million years ago
Ancient super-eruptions in Yellowstone Hotspot track ‘significantly larger’ than expected

Dr Tom Knott at the base of a typical thick Snake River-type ignimbrite >40 m-thick.

A number of giant super-eruptions between 8 and 12 million years ago that could be larger than the colossal eruptions known to have taken place at Yellowstone have been identified in the United States through research led by Dr Tom Knott, Professor Mike Branney and Dr Marc Reichow from the Department of Geology.

The international research team suggests that while the number of volcanic eruptions thought to have originated from the central Snake River Plain in Idaho, USA is less than previously believed, the 12 recorded giant eruptions were likely ‘significantly larger’ than research has previously suggested.

Using a multi-technique approach, including whole-rock and mineral chemistries, palaeomagnetic data, and radio-isotopic dates, the team has been able to ‘fingerprint’ individual eruption deposits and correlate these over vast regions (e.g., 1000’s km2). 

In establishing widespread correlations, the team drastically reduced the number of eruptions previously thought to have originated from the central Snake River Plain by more than half.

The researchers have reported that one of the super-eruptions from the Yellowstone hotspot-track, defined as the Castleford Crossing eruption, occurred about 8.1 million years ago and estimate the eruption volume to have exceeded 1,900 km3. The single volcanic sheet covers an area over 14,000 km2 in southern Idaho, and is more than 1.3 km thick in the caldera of the super-volcano.

Dr Knott said: "The size and magnitude of this newly defined eruption is as large, if not larger, than better known eruptions at Yellowstone, and it is just the first in an emerging record of newly discovered super-eruptions during a period of intense magmatic activity between 8 and 12 million years ago.”

Several former Leicester undergraduates, including Mark Baldwin, Stuart Hatter, Liam McDonnell, Fabian Wadsworth and Luke Wooldridge, helped with the US fieldwork. They also enjoyed the opportunity of gaining experience through interacting with the international team of scientists.