Tiny crystals predict a huge volcano in western U.S.

July 20, 2001

MADISON - Reading the geochemical fine print found in tiny crystals of the minerals zircon and quartz, scientists are forming a new picture of the life history - and a geologic timetable - of a type of volcano in the western United States capable of dramatically altering climate sometime within the next 100,000 years.

With insight gained from new analytical techniques to study crystals of zircon and quartz, minerals that serve as veritable time capsules of geologic events, a group of scientists from the University of Wisconsin-Madison has proposed a new model for the origin of volcanism in young calderas.

These are volcanoes that occur over "hot spots" in the Earth and they erupt every few hundred thousand years in catastrophic explosions, sending hundreds to thousands of cubic kilometers of ash into the atmosphere and wreaking climatic havoc on a global scale.

In a series of papers, UW-Madison geologists Ilya N. Bindeman and John W. Valley present a life history of the hot spot volcanism that has occurred in the Yellowstone basin of the western United States over the past 2 million years. Their findings suggest a dying, but still potent cycle of volcanism, and a high probability of a future catastrophic eruption sometime within the next million years, and possibly within the next hundred thousand years.

Today's Yellowstone landscape represents the last in a sequence of calderas - the broad crater-like basins created when volcanoes explode and their characteristic cones collapse - that formed in regular progression over the past 2 million years. The near-clockwork timing of eruptions there - 2 million years ago, 1.3 million years ago and 600,000 years ago - suggests a pattern that may foreshadow an eruption of catastrophic proportions, said Bindeman and Valley.

Beneath Yellowstone and its spectacular landscape of hot springs and geysers is a hot spot, an upwelling plume of melted rock from the Earth's mantle. As the plume of hot, liquid rock rises in the Earth, it melts the Earth's crust and creates large magma chambers.

"These magmas usually erupt in a very catastrophic way," said Bindeman. "By comparison, the eruption of Mount St. Helens sent about two cubic kilometers of ash into the atmosphere. These catastrophic types of eruptions send thousands of cubic kilometers of ash skyward."

The hot spot deep beneath Yellowstone acts like a burner, said Bindeman. "It's a constant source of heat that acts on the upper crust and forms magma chambers that contain tens of thousands of cubic kilometers" of molten rock.

One of the massive plates that helps make up the crust of the Earth, the North American plate, is slowly moving over the hot spot, said Bindeman. "The plate has been moving across the heat source which makes it seem like the volcanoes are moving across the continent. Moreover, we have a progression of explosive eruptions which seem to have some periodicity."

Bindeman and Valley studied rocks that span the entire 2-million-year long eruptive sequence at Yellowstone with a special emphasis on lavas that erupted the last time one of the massive volcanoes popped off creating what geologists call the Yellowstone Caldera. Their conclusion is that the volcanic cycle is waning, but that there is still a very real potential of an eruption of massive proportions sometime in the near geologic future.

Such an eruption would disrupt global climate by injecting millions of tons of ash into the atmosphere. Some of the ash would remain in the atmosphere for years, reflect sunlight back into space and cool the planet, significantly affecting life. In addition, a blanket of ash over a meter thick would be deposited in nearby regions and effectively smother life there.

The most recent caldera is 600,000 years old and encompasses an area of more than 2,000 square kilometers. When it erupted, it blasted 1,000 cubic kilometers of volcanic rock into the atmosphere and it settled as ash over more than half of the United States.

After that last major eruption, volcanism in Yellowstone continued in a quieter fashion with another, much smaller eruption occurring 70,000 years ago.

Today's spectacular geysers and hot springs at Yellowstone are the most visible part of the volcanic system there. They contain heated snow and rainwater which leave a geochemical record that provides insight into the region's geologic activity. Prior to the last catastrophic eruption at Yellowstone 600,000 years ago, an even more spectacular geothermal landscape existed there, said Bindeman.

"The unique thing about Yellowstone is that the volcanic rocks that erupted following the collapse of the big calderas contain up to 50 percent oxygen which was ultimately derived from rain waters," Bindeman said. "The zircon and quartz tell us that rocks near the surface were altered by heated snow and rainwater. These rocks were then remelted to become magmas."

This scenario changes the view of magmatism at Yellowstone and other calderas as representing new magma coming from deep in the Earth. On the contrary, Bindeman and Valley make a case for the total remelting and recycling of previously erupted surface rocks.

Their findings have been published in a series of papers, the first in the August 2000 edition of the journal Geology. Another paper is to appear this month (July) in Earth and Planetary Science Letters, and another is scheduled for publication next month (August) in the Journal of Petrology.
CONTACT: John W. Valley, 608-263-5659, valley@geology.wisc.edu;Terry Devitt 608-262-8282, trdevitt@facstaff.wisc.edu

NOTE TO GRAPHICS/PHOTO EDITORS: An informational graphic in EPS outline version and a high-resolution JPEG image is available for downloading at: http://www.news.wisc.edu/newsphotos/quartzvolcano.html

University of Wisconsin-Madison

Related Yellowstone Articles from Brightsurf:

Discovery of ancient super-eruptions indicates the yellowstone hotspot may be waning
Throughout Earth's long history, volcanic super-eruptions have been some of the most extreme events ever to affect our planet's rugged surface.

Reintroduction of wolves tied to return of tall willows in Yellowstone National Park
The reintroduction of wolves into Yellowstone National Park is tied to the recovery of tall willows in the park, according to a new Oregon State University-led study.

Bison in northern Yellowstone proving to be too much of a good thing
Increasing numbers of bison in Yellowstone National Park in recent years have become a barrier to ecosystem recovery in the iconic Lamar Valley in the northern part of the park.

What happens under the Yellowstone Volcano
A recent study by Bernhard Steinberger of the German GeoForschungsZentrum and colleagues in the USA helps to better understand the processes in the Earth's interior beneath the Yellowstone supervolcano.

Fearing cougars more than wolves, Yellowstone elk manage threats from both predators
Wolves are charismatic, conspicuous, and easy to single out as the top predator affecting populations of elk, deer, and other prey animals.

What drives Yellowstone's massive elk migrations?
Yellowstone's migratory elk rely primarily on environmental cues, including a retreating snowline and the greening grasses of spring, to decide when to make the treks between their winter ranges and summer ranges, shows a new study led by University of California, Berkeley, researchers.

Aftershocks of 1959 earthquake rocked Yellowstone in 2017-18
A swarm of more than 3,000 small earthquakes in the Maple Creek area (in Yellowstone National Park but outside of the Yellowstone volcano caldera) between June 2017 and March 2018 are, at least in part, aftershocks of the 1959 quake.

Resilience of Yellowstone's forests tested by unprecedented fire
The University of Wisconsin-Madison's Monica Turner and her team describe what happens when Yellowstone -- adapted to recurring fires every 100 to 300 years -- instead burns twice in fewer than 30 years.

Yellowstone elk don't budge for wolves say scientists
Elk roam the winter range that straddles the northern boundary of Yellowstone National Park with little regard for wolves, according to a new study illustrating how elk can tolerate living in close proximity to the large predator.

Researchers find broad impacts from lake trout invasion in Yellowstone
The scientists analyzed data spanning more than four decades and concluded that the impact of lake trout in Yellowstone Lake -- in particular, the decline of native cutthroat trout -- has cascaded across the lake, its tributaries and the surrounding ecosystem.

Read More: Yellowstone News and Yellowstone Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.