Researchers find evidence of TWELVE catastrophic mega eruptions 16m years ago in Idaho
- These eruptions were hotter and probably more frequent than Yellowstone
- This activity took place during in the past 16 million years, in mid-Miocene
- Cataclysmic eruptions resulted in a deep volcanic basin along Snake River
By Cheyenne Macdonald For Dailymail.com
Published: 11 March 2016
In the past 16 million years, a series of massive volcanic eruptions spewed deposits on a southern Idaho landscape, attaining heat more intense than that produced by Yellowstone.
A team of researchers has revealed evidence at Cassia Hills of 12 previously undiscovered eruptions, where the land still holds deposits of magnetic, mineralogical, and chemical characteristics.
These catastrophic eruptions are thought to have been produced from different sources, all within the stretch of a deep volcanic basin.
In the past 16 million years, a series of massive volcanic eruptions spewed deposits on a southern Idaho landscape, attaining heat more intense than that produced by Yellowstone. Mexico's 'Fire Volcano' in Colima, pictured above
THE MASSIVE ANCIENT ERUPTIONS
Researchers have revealed evidence at Cassia Hills of 12 previously undiscovered eruptions.
Deposits of magnetic, mineralogical, and chemical characteristics suggest these eruptions were all from different sources.
But, they all took place within the deep volcanic basin along the Snake River Plain.
In the paper, researchers say the findings reveal 'one of the most complete successions of mid-Miocene Snake River volcanism in the region,' and eruptions may have been as large as those at Yellowstone.
And, these ancient eruptions were hotter and likely more frequent.
The work, led by Thomas R. Knott and a team of researchers, has discovered evidence of ancient eruptions which scorched the land from Oregon toward Yellowstone.
Researchers say these events during the mid-Miocene epoch were hotter and likely more frequent than the Yellowstone eruptions, and left a deep volcanic basin along the Snake River Plain.
In the 1.9 km thick Cassia Formation, the team found evidence of 12 distinctive eruptions.
These eruptions would have stemmed from different sources, and the deposits in the area reveal unique characteristics in field, geochemical, mineralogical, geochronological, and paleomagnetic makeup.
Between 11.3 and 8.1 million years ago, the eruptions left behind high volumes of deposits and ash-fall.
Using this information, the researchers found that one of these events, the Castleford Crossing eruption roughly 8.1 million years ago, was a 'super eruption.'
Elements in the deposits reveal three trends toward less-evolved composition, separated by abrupt returns to more-evolved composition.
Researchers suggest each cycle records the renewal of intraplating, a type of 'hot spot' volcanic activity that comes from within tectonic plates.
Researchers say these events during the mid-Miocene epoch were hotter and likely more frequent than the Yellowstone eruptions, and left a deep volcanic basin along the Snake River Plain. In the 1.9 km thick Cassia Formation, the team found evidence of 12 distinctive eruptions
This may have occurred as the North American plate moved westward, passing above the Yellowstone hotspot.
During these cycles, the researchers discovered an increase in basaltic magma from the mantle.
The team has linked northwest trending faulting in this area to the opening of the western Snake River rift and E-W Basin and Range extension
Over the course of the many eruptions, the activity caused the Earth's crust to subside by more than three kilometres, differentiating this area from today's more elevated Yellowstone plateau.
In the paper, researchers say the findings reveal 'one of the most complete successions of mid-Miocene Snake River volcanism in the region,' and eruptions may have been as large as those at Yellowstone.
SCIENTISTS FIND MASSIVE NEW MAGMA CHAMBER UNDER YELLOWSTONE
Previous research found a relatively small magma chamber, known as the upper-crustal magma reservoir, beneath the surface
In the heart of Yellowstone National Park, a supervolcano releases around 45,000 metric tonnes of carbon dioxide each day.
But the magma chamber lying directly beneath its surface is not considered large enough to produce such levels, so researchers have been searching for an alternative source for years.
In April, by tracking seismic waves, geophysicists discovered a huge secondary chamber deeper underground that's so large its partly-molten rock could fill the Grand Canyon 11 times over.
Previous research found a relatively small magma chamber, known as the upper-crustal magma reservoir, directly beneath the surface in 2013 that measures 2,500 cubic miles (10,420 cubic km).
To discover the latest chamber, Hsin-Hua Huang from the University of Utah and his colleagues tracked seismic waves from almost 5,000 earthquakes.
These readings combined data from the University of Utah Seismograph Stations, which collected shallow readings from nearby quakes in Utah, Idaho, the Teton Range and Yellowstone, and from the Earthscope array, which revealed deeper readings from temblors from more further afield.
Each of these quakes created waves that echoed around the supervolcano.
The movement and structure of these waves could then be used to map the earth beneath.
The researchers said in their paper: 'The Yellowstone magmatic system from the mantle plume to the upper crust', published in the journal Science, that the reservoir contains around 98 per cent hot rock.
The remaining 2 per cent is molten rock and is too deep to directly cause an eruption, they added.
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