A team of geologists from
Brigham Young University - BYU - led by Eric Christiansen and Myron Best, highlighted one of the largest eruptions on Earth.
Storm on the Wah valley - photo Qfl247
Geologists have identified in the area a couple
of large eruptions and no less than 20 large calderas . These volcanoes are not active today .
A volume of magma
over 5,500 km ³ has been issued by one of these super- eruptions, over a very short period of about a week at a place called Wah Wah Springs.
BYU's
geologists M.Best and E.Christiansen on the Wah Wak springs site . - BYU Photo
These events are dated to 30 million years . In comparison with the eruption
of St. Helens in 1980 , although its nature is different, the Wah springs eruption is about 5,000 times greater .
Etymologically, " Wah Wah " translates to " a good clear water."
The dacitic tuff Wah springs is one of the largest volumes of ignimbrites issued during the peak of activity in the large ignimbrite basin of western North America
.
The eruption buried a vast region
extending from central Utah to central Nevada , from Fillmore to the north to Cedar City to the south. Traces of ash
were found to Nebraska .
Situation of the Indian Peak caldera in the Great Basin
- the tuffs Wah Wah springs emanate from the caldera - doc . USGS
Wah Wah mountains - Indian Peak -
photo Summitpost
In
southern Utah , deposits of this unique eruption reach a thickness of 3.900 meters, which leaves imagine how this episode was disastrous .
The deposits were subjected to various analyzes : fluorescence X - ray , chemical analyzes of minerals, dating to verify that this ignimbrite did belong to the same old super-
eruption.
At that time , dinosaurs are already extinct , but preserved in these ancient volcanic deposits flora and fauna indicate a different climate of the present day : there are palm trees , rhinos ,
camels and turtles.
Wah Wah springs caldera is estimated at 40 km. wide, with a depth of about 5 km., at the time of its
formation ... comparable to the Yellowstone size ( Wyoming).
The
ravages of erosion and deformation then transformed the landscape , so that despite its huge size, this eruption and this super- volcano remained " hidden " for millions of years ... and it took
the involvement and the work of hundreds of students and teachers to rediscover
.
The Wah Wah
range - straddling Utah and Nevada
In
the northern part of the Wah Wah mountains, Crystal Peak slice of the surrounding landscape and is composed of erosional
remnants of rhyolitic tuff Paleogene, containing an abundance of quartz crystals double tip .
The Wah Wah mountains and Crystal Peak -
Summitpost pictures.
A series of thrust faults cuts the sedimentary rocks south of Wah
Wah mountains . It is known as the cradle of red
beryl, more expensive than gold gemstone ... we will consider in a later article.
Sources :
- Brigham Young University - Supervolcanoes discovered in Utah by BYU geologists - link
- Geosphère - The 36-18 Ma Indian Peak - Caliente ignimbrite field and calderas, southeastern Great Basin, USA : multicyclic super-eruptions - by M.Best, E.Christiansen & al. - link
- Nasa ADS - Pre-eruptive conditions in the Wah Wah springs tuff : no evidence of thermal rejuvenation - by Woolf, Christiansen, Best & Dorais.- link
- USGS - Stratigraphy of the volcanic Oligocene needles Range group
- Summitpost - Wah Wah Mountains
