Subscribe to our free daily newsletters
. 24/7 Space News .

Subscribe to our free daily newsletters

Cataclysm at Meteor Crater: Crystal sheds light on Earth, moon, Mars
by Staff Writers
Madison WI (SPX) Jul 28, 2016

New research at Meteor Crater shows extreme temperatures and pressures during the impact that created the crater 49,000 years ago. Image courtesy Aaron Cavosie. For a larger version of this image please go here.

In molten sandstone extracted by prospectors a century ago, an international team of scientists has discovered microscopic crystals telling of unimaginable pressures and temperatures when a 12-kilometer asteroid formed Meteor Crater in northern Arizona some 49,000 years ago.

The crystals, called zircons, have endured temperatures of 2,000 degrees Celsius or more, hot enough to melt any rock on Earth. In our planet's crust, such temperatures occur only briefly inside impact zones, says Aaron Cavosie, a visiting professor in the Wisconsin Astrobiology Research Consortium at the University of Wisconsin-Madison.

Zircons are tiny, phenomenally stable crystals that can persist for billions of years and have been used to date ancient asteroid impacts. But the new study, now online in the journal Geology, sheds light on a more recent impact at Meteor Crater, which may be the best studied impact zone on Earth. "It's fresh, young and easy to get to," says Cavosie, who is also a senior research fellow at the Western Australian School of Mines, Curtin University, in Perth, Australia.

In an electron microscope, the zircons look like agglomerations of BBs. Such "granular" zircons are also found in a giant impact crater in South Africa and on the moon, "but until now no one has cracked the code to figure out what turned normal zircons into thousands of grains glued together," Cavosie says.

Cavosie's group, including Nick Timms and Curtin Ph.D. candidate Timmons Erickson, along with collaborators Justin Hagerty from the U.S. Geological Survey and Fred Horz from NASA, strung together several lines of evidence to conclude that the zircons had been subjected to a pressure of at least 300,000 atmospheres, and temperatures above 2,000 degrees C.

When the researchers fired a beam of electrons at 14 zircons, the electrons scattered back to a detector revealed the chemistry and the complex structure of the zircons. "When we looked at the texture of these unusual zircons, we saw that the orientations of the BBs are non-random, and instead are highly systematic," Cavosie says.

These zircons are so tiny that eight, lined up, would extend across the width of a hair.

The orientations "record a series of changes that happen as zircons get shocked at increasing pressures - think Dante's levels of hell for zircons," Cavosie says. A moderate level of shock creates planar cleavages, "but as you go to higher levels, the zircon makes a twin, which is what happens when parts of a crystal are forced into a different orientation. This specific change is only caused by impact, and we have seen it in other places."

Another distinctive orientation "only forms when zircon changes to the extremely rare mineral reidite," Cavosie says. "This transformation is proven in the lab to require even more extreme pressures than twins."

Finally, the impact created such an extraordinarily high temperature that it vaporized or melted all rocks in the surrounding crust. The quartz grains in the sandstone fused into the glassy, "shock-melted silica" that encased the zircons.

"When we screwed all these parts together," Cavosie says, "the orientation of the granular zircons, the pressure required to form the twin phase and then reidite, and the finding that zircons were briefly swimming in a pool of liquid silica at about 2,000 degrees, hot enough for the zircons to recrystallize into this beebee-like granular texture, and then the evidence that this cooled very quickly, we saw that the granular zircons left a trail of breadcrumbs that allowed us to reconstruct how they were made, and in what conditions."

Extreme pressures and temperatures that quickly subside comprise an unusual realm for geology. "Geologists are used to thinking about slow processes," Cavosie says. "The process that transforms carbon into diamond is slow and steady; it involves high pressure and temperature but happens over millions of years."

The equally dramatic transformation that creates a granular zircon occurs over a few minutes at most. "Then, the extreme pressure is gone, the high temperature has cooled off," Cavosie says. "The impact leaves a giant hole in the ground, but it takes a mental adventure to wrap your head around the fact that the transformation in these zircons happened in seconds to minutes."

The significance of understanding the formation of granular zircons extends far beyond one large meteor crater, Cavosie says. "These granular zircons have been found in meteorites, whose history we know very little about. Now, when we find them in a meteorite, it will allow us to recreate the conditions that the meteorite experienced on its path to Earth."

The same is true for rocks returned from Mars and the moon, Cavosie says, and indeed he's already investigating some moon rocks returned by the Apollo program.

"The new diagnostic techniques reported by Cavosie and colleagues will aid in cataloging impact events on Earth and elsewhere in the solar system," says zircon expert John Valley, a professor of geoscience at UW-Madison. "This is important for understanding the history of Earth and the emergence of life. It will also aid in predicting the frequency of future large impacts to Earth, equivalent to the one that killed off the dinosaurs 65 million years ago, nearly extinguishing all life on land."

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only


Related Links
University of Wisconsin-Madison
Asteroid and Comet Impact Danger To Earth - News and Science

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Previous Report
Planetary Defense
Huntsville AL (SPX) Jul 12, 2016
Dinosaurs were fearsome creatures. Some had thick scales, sharp teeth, and, in many cases, lightning-fast reflexes. One thing they didn't have: a planetary defense office. When an asteroid targeted Earth 65 million years ago, it took those masters of Earth by complete surprise. While we know of no large object that is on a collision course with Earth in the next 100 years, descendants of survivo ... read more

Asteroid that formed moon's Imbrium Basin may have been protoplanet-sized

Russian and US engineers plan manned moon mission

SSTL and Goonhilly announce partnership and a call for lunar orbit payloads

Taiwan to make lunar lander for NASA moon-mining mission

Digging deeper into Mars

NASA's Viking Data Lives on, Inspires 40 Years Later

Opportunity Rover wrapping up work within Marathon Valley

NASA Mars Rover Can Choose Laser Targets on Its Own

Russia, US Discuss Lunar Station for Mars Mission

Disney theme park in Shanghai nears a million visitors

NASA Sails Full-Speed Ahead in Solar System Exploration

Sensor Technology Could Revolutionize What You Sleep On

China commissions space tracking ship as new station readied

China's second space lab Tiangong-2 reaches launch center

Dutch Radio Antenna to Depart for Moon on Chinese Mission

Chinese Space Garbageman is not a Weapon

Russia launches ISS-bound cargo ship

New Crew Members, Including NASA Biologist, Launch to Space Station

Russian New Soyuz-MS Spacecraft Docks With ISS for First Time

NASA Highlights Space Station Research Benefits, Opportunities at San Diego Conference

India earned Rs 230 crore through satellite launch services in FY16

US Plan to Diversify Expendable Space Launch Vehicles Being Questioned

Intelsat 33e arrives at the Spaceport for Arianespace's August launch with Ariane 5

The rise of commercial spaceports

Alien Solar System Boasts Tightly Spaced Planets, Unusual Orbits

Atmospheric chemistry on paper

First atmospheric study of Earth-sized exoplanets reveals rocky worlds

Surface Composition Determines Planet's Temperature and Habitability

A third of U.S. adults say they'd be enthusiastic about a microchip implanted in brain

NASA to Begin Testing Next Generation of Spacecraft Heat Exchangers

Active tracking of astronaut rad-exposures targeted

NASA Establishes Institute to Explore New Ways to Protect Astronauts

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement