Ancient super-eruptions in Yellowstone Hotspot track 'significantly larger' than expected
Dr Tom Knott, Professor Mike Branney and Dr Marc Reichow, from the University of Leicester's Department of Geology's Volcanology Group, conducted the research with a team of international collaborators from the University of California, Santa Cruz, the University of Copenhagen, Denmark and Idaho State University.
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.
|Scenic canyon in southern Idaho, USA, which beautifully exposes several cliff-forming, |
intensely-welded deposits each recording an individual giant eruption
[Credit: Marc Reichow/University of Leicester]
This is just one of 12 giant eruptions reported from the area by the Leicester team, who show that intense hotspot magmatism caused major crustal subsidence, forming the 100 km-wide Snake River Basin. The team also demonstrates that these eruptions were in fact significantly larger than previously thought and may rival those better known at Yellowstone.
Dr Knott said: "While it is well-know that Yellowstone has erupted catastrophically in recent times perhaps less widely appreciated is that these were just the latest in a protracted history of numerous catastrophic super-eruptions that have burned a track along the Snake River eastwards from Oregon to Yellowstone from 16 Ma to present.
"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."
The paper has been published in the journal Geological Society of America Bulletin.
Source: University of Leicester [March 24, 2016]